"Is'

ORGANOMAGNESIUM COMPOUNDS IN BENZENE SOLVENT

AND THEIR APPLICATION IN SYNTHESIS

OF ORGANOBERYILIUM COMPOUNDS

THESIS

Presented to the Graduate Council of the

North Texas State University in Partial

Fulfillment of the Requirements

For the Degree of

MASTER OF SCIENCE

By

Charles M. Selman, B. S.

Denton, Texas

January, 1966

TABLE OF CONTENTS

PageLIST OF TABLES . . . . . * . . . . . . . . . . . . . . iv

LIST OF ILLUSTRATIONS .0.... *.. . . . .. 0 .0. .0 v

Chapter

I. INTRODUCTION. . . . . . . . . . . . . . . . . . . 1

II. EXPERIMENTAL PROCEDURE .0.0.0. . . .0.0.a. .*. . 12

MaterialsPreparation and Analysis of the Organo-

magnesium HalidesCryoscopic Molecular Weight DeterminationPreparation and Analysis of Di-n-

pentylmagnesium,Preparation and Analysis of Organo-

beryllium CompoundsInfrared Absorption Studies

III. RESULTS AND DISCUSSION........*... . . . . . 30

BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . 46

iii

LIST OF TABLES

Table Page

I. InvestigationSummary--a-........ 5

II. Impurity Analysis of Magnesium . . . . . . . . . . 12

III. Analysis of n-Pentylmagnesium Compounds inBenzene Solvent . . . . . . . . . . . . . . .31

IY. Molecular Structure Dependence Upon theOrganic Portions of OrganomagnesiumHalide Compounds in Benzene Solvent . . . . . .38

V. Synthesis and Association Studies of Organo-berylliummCompounds . ......... ... 40

VI. Infrared Absorptions ............... 43

VII. Electronegativity and Mass Values . . . . . . . . . 44

iv

LIST OF ILLUSTRATIONS

Figure Page

1. Molecular Weight Apparatus . . . . . . . . . . . . 18

2. Hydrolysis Apparatus . . . . . . . . - - . - - - . 26

3. Nuclear Magnetic Resonance Monitoring of theDi-n-pentylmagnesium Synthesis . . . . . . . . 34

4. Infrared Spectra of 1-Pentylmagnesium HalideComplexes in Benzene . . . . . . . . . . . . . 42

V

CHAPTER I

INTRODUCTION

The concept that organomagnesium compounds are of two

kinds, the di-organomagnesium compounds, R2Mg, and the

organomagnesium halide compounds, RMgX, was accepted until

the early part of this decade. Several attempts had been

made to prepare the organomagnesium halide species by methods

other than the classical Grignard procedure, with little

success (12). The products which resulted from these at-

tempts using hydrocarbon solvents were generally described

as involatile and infusible solids which showed little if

any solubility in hydrocarbon solvents. Due to lack of

analysis, these products were assumed to have the RMgX

structure that was used to describe the Grignard reagent.

Procedures for the preparation of organomagnesium halide

compounds in the absence of ether have been reported in

several recent publications (4, 5, 16, 17). These publi-

cations describe techniques for preparingthe organomagnesium

halide species which consist of direct addition of alkyl or

aryl halides to magnesium metal. These organomagnesium

halides are formed in the absence of the usual ethereal

solvent and exhibit a degree of solubility in hydrocarbon

solvents which is primarily dependent upon the organic radical.

1

2

Zokharkin, Okhobystin, and Strubin (16) carried out a

systematic investigation to determine the optimum synthetic

conditions and the yields of these organomagnesium halide

compounds. They reported the yields on the whole to be

comparable to those in ether solutions. In a later paper

(17), these authors showed that organomagnesium compounds in

hydrocarbon solvents are useful for the synthesis of a variety

of organometallic compounds.

Bryce-Smith and Cox (5) found the solubilities of organo-

magnesium halides to increase in the order Cl<Br <I, and to

increase with the length of the alkyl chain of the organo-

magnesium halide. For the system of n-butyl magnesium iodide

in isopropyl benzene and tetrahydronapthalene an empirical

formula R3 Mg2X was found to be representative of the solutions.

An explanation of the observed empirical formula R3Mg2X by the

species R2Mg and RMgX is precluded by the low solubility observed

for di-n-butylmagnesium in boiling isopropyl benzene. A com-

bination of the determined empirical formula and the rather

high relative viscosity values of these solutions led the

authors to predict polymeric organomagnesium halide species

with repeating units of the following types:

(a) or (b)

'.:.-Mg 0MgJ -,'0.Mg . :.Mg Mg*. ..- . .- X -' - ---.- R-'x4' -X ' - ''

3

The dotted lines in these structures represent electron-

deficient bonding which had been predicted for linear polymeric

structures of dimethylberyllium (13). Additional evidence for

this polymeric structure was the observation of magnesium

halide precipitation from concentrated solutions upon standing,

resulting in larger alkyl to halide ratios. This dispropor-

tionation by elimination of MgX2 was taken as favoring the

(b) repeating polymeric unit over (a).

The work reported by D. Bryce-Smith and G. F. Cox (5)

along with several recent publications describing experimental

results designed to elucidate the long disputed question of

the structure of the Grignard reagent in ether stimulated

the work reported here, in an effort to obtain additional

evidence of the structure of the organomagnesium complex in

benzene solvent. Since the primary objective of this work

was to prepare organoberyllium compounds using the organo-

magnesium complexes in hydrocarbon solvents, it seemed an

insight into the structure of these complexes would be bene-

ficial in this work.

The techniques used and experimental evidence obtained

from the structure elucidation of the ethereal Grignard re-

agent have been most helpful in organization of the methods

used to study the structure of organomagnesium halide com-

plexes in benzene solvent. For this reason a review of the

most important publications leading to the structure deter-

mination of the Grignard reagent will be presented here.

4

During the early part of this century two main pro-

posals for the structure of the Grignard reagent were made.

The well-known formula RMgX was first proposed by Grignard

(10). The other formula, R2Mg . MgX2, was proposed by

Jolibois (11). The work by R. E. Dessy (8) described ex-

periments which indicated that the species RMgX was es-

sentially non-existent in Grignard solutions, which up until

this time had been represented by the equilibria

2RMgX #=N!! R2Mg -FMgX2 # R2Mg . MgX2

In this paper and in a later publication (9) Dessy presented

evidence that was interpreted to show that equimolar mixtures

of MgBr2 and Et2Mg in ether had the same characteristics as

the Grignard reagent, and when Mg28Br2 was used no exchange

between the organomagnesium and the magnesium halide was

observed. Consequently, Dessy concluded that no alkyl ex-

change takes place in ether solution and therefore the left

side of the above equilibrium was not important in the de-

scription of the system.

The work by Dessy was widely accepted and little pursuit

of the Grignard structure was made by investigators until the

early part of this decade. Recently, however, several pub-

lications (2, 14, 15, 16) by different investigators have

shown evidence for the existence of RMgX species both in

diethyl ether and tetrahydrofuran solvents.

5

The primary techniques used by these investigators were

ebullioscopic studies for molecular association determinations

and gas chromatography and neutralization determinationsfor

stoichiometry studies. The work by G. D. Stucky and R. E.

Rundle (14) applied the technique of X-ray diffraction to

determine the crystal structure of the phenylmagnesium bromide

Grignard reagent. A summary of the findings of these in-

vestigators is shown in the following table:

TABLE I

INVESTIGATION SUMMARY

Authors Reference Solvent Grignrd AsociationReagentSpecies

E. C. AshbyW. E. Becker (2) THF EtMgCl Monomer

EtMgBr MonomerEt20 EtMgCI Dimer

MeMgCl DimerMesitylMgBr. Dimer

G. D. StuckyR. E. Rundle (13) Crystalline PhMgBr Monomer

di-etherateC. Blomberg (14, 15) Et20 EtMgBr Monomer

___THF EtMgBr Monomer

The main points that can be determined from the above summary

of data are: the species RMgX does exist in ether solvent,

and the exact nature of the Grignard reagent is dependent

upon the variables of solvent, R group, and halide.

Two recent publications by E. C. Ashby (1, 3) make very

clear the dependence of the Grignard reagent structure upon

6

the variables of solvent, R group, and halide. This was

accomplished first by presenting data which shovsthat the

degree of association of several Grignard reagents in

diethyl ether solvent varies between one and two in the con-

centration range 0.1 - 0.4 molarity. The data also shows that

the chloride species demonstrates this effect very little

compared to the bromide and iodide species. Ashby concluded

that re-evaluation of the data summarized in Table I with

respect to the association-concentration dependence leads to

the conclusion that RMgX species definitely exist in solution.

This evaluation thus provides evidence that dimeric species

in solution can be explained by both a symmetrical (RMgX)2

and an unsymmetrical R2Mg . MgX2 species. From these results

the Grignard structure in diethyl ether can thus be charac-

terized by a monomeric species, which exists as: (A) RMgX;

(B) a mixture of R2Mg and MgX2 ; (C) an equilibrium mixture of

(A) and (B). The Grignard structure in diethyl ether may also

be characterized by a dimeric species stated to be present in

(D) a symmetrical dimer or (E) an unsymmetrical dimer. This

equilibriumis shown in the following diagram:

OX% R XR-Mg' Mg-R" -2RMgX-hR 2 Mg + MgX2 Mg Mg

(D) (A) (B) (E)

The second article by Ashby (1) explains the distinction

between the composition of the Grignard compounds in diethyl

7

ether and tetrahydrofuran solvents by the difference in

basicity of the two solvents. Thus, tetrahydrofuran co-

ordinates with magnesium more strongly than diethyl ether

and a bridge compound is not formed. By applying an even

stronger base such as triethyl amine Ashby showed that the

Grignard reagent revealed only monomeric species throughout a

wide concentration range. This work gives a more complete

picture of organomagnesium halide complexes in a medium which

shows enough basic character to associate with the magnesium

in the complex. A knowledge of the different parameters,

which had to be understood before the structure of the organo-

magnesium halide complex in polar solvents could be elucidated,

was very helpful in designing experiments that would give some

insight into the structure of the organomagnesium halide com-

plexes in non-polar hydrocarbon solvents.

It seemed that an insight into the structure of these

organomagnesium halide complexes in hydrocarbon solvents

would be beneficial in accomplishing the second objective of

this work. This objective was to prepare organoberyllium

compounds using the organomagnesium halide complexes prepared

in hydrocarbon solvents. This method could offer advantages

over the known methods of preparation described below:

1. Preparation by the action of the classical Grig-

nard reagent on beryllium chloride. This is the most com-

monly used method for the preparation of dialkylberyllium

compounds.

8

2RMgX + BeCl2 ---+ R2 Be + MgX2 + MgCl22. Metallic beryllium can be reacted with organo-

mercury compounds. Dimethyl, diphenyl, and di-p-

tolylberyllium have been prepared by this method (6).

R2Hg + Be -4 BeR2 + Hg

The first method described is a very effective method

for preparing organoberyllium compounds. For the preparation

of pure organoberyllium compounds, this method has one main

disadvantage, since all the known organoberyllium compounds

retain ether with great tenacity. An example of the difficulty

of the removal of ether was related by Coates (7). He reported

that a diisopropylberyllium preparation which had twice been

distilled and pumped in vacuum for two days was found, upon

hydrolysis, to have retained 16 per cent by weight of ether.

The second method has several undesirable characteristics.

The main disadvantage is the amount of time required to carry

out this preparation. Although they are expensive, some organo-

mercury compounds may be purchased. If it is necessary, these

compounds may be prepared from Grignard reagents; however, the

synthesis is very time consuming.

The method of preparation of organoberyllium compounds

from organomagnesium halide complexes in benzene solvent

should be superior to the methods now used to prepare organo-

beryllium compounds. The main advantages will be that ether

is not required as a solvent and only the organomagnesium

9

halide complex and beryllium chloride are needed for the

reaction. The preparation of an ether-free organoberyllium

compound will be very beneficial in studying the properties

of organoberyllium compounds.

CHAPTER BIBLIOGRAPHI

1. Ashby, E. C., "Proof for the RMgX Composition of Grig-nard Compounds in Diethyl Ether. RMgX, the InitialSpecies Formed in the Reaction of RX and Mg," Journalof the American Chemical Society, LXXXVII (1965),25U9.

2. Ashby, E. C. and W. E. Becker, "Concerning the Structureof the Grignard Reagent," Journal of the AmericanChemical Society, LXXXV (1963), 118.

3. Ashby, E. C. and Martin B. Smith, "Concerning the Structureof the Grignard Reagent. II. In Diethyl Ether. Rele-vance of Grignard Composition to the Mechanism ofAddition to Ketones," Journal of the American ChemicalSociety, LXXXVI (1964), 4363.

4. Bryce-Smith, D., "Unsolvated Organomagnesium Complexes,"Bulletin de la Societe Chimgue de France, VII (1963),1418.

5. Bryce-Smith, D. and G. F. Cox, "Organometallic Compoundsof Group II. Part III. Unsolvated OrganomagnesiumHalides," Journal of the Chemical Society (1961), 1175.

6. Coates, G. E., Organo-Metallic Compounds, London, Methuenand Company, Ltd., 197.

7. Coates, G. E. and F. Glockling, "Diisopropylberylliumand Some Beryllium Hydrides," Journal of the ChemicalSociety (1954), 22.

8. Dessy, R. E., G. S. Handler, J. H. Wotiz, and C. A.Hollingsworth, "The Constitution of the Grignard Re-agent," Journal of the American Chemical SocLXXIX (1957), T47.,

9. Dessy, R. E. and G. S. Handler, "The constitution ofthe Grignard Reagent," Journal of the American ChemicalSociety, LXXX (1958), 5826.

10. Grignard, V., "Sur les conbinaisons organmagnesiennesmixtes et leur application a des syntheses d'acides,d'alcools et d'hydrocarbures," Annales de Chimie,XXIV (1901), 433.

10

11

11. Jolibois, M. Pierre, "Sur la formule du derive organo.-magnesien et sur l t hydrure de magnesium," ComptesRendus Hebdomadaires des Seances, CLV (1912, 357.

12. Rochow, Eugene,G., Dallas T. Hurd, and Richard N.Lewis, The Chemistry of Organometallic Compounds,New York ,JohnWiley an~d S-nsInc. 1957

13. Snow, A. I. and R. E. Rundle, "The Structure ofDimethylberyllium," Acta Crystallographic, IV (1950),348.

14. Stucky, G. D. and R. E. Rundle, "The Structure ofPhenylmagnesium Bromide Dietherate and the Natureof Grignard Reagents," Journal of the American ChemicalSociety, LXXXV (1963), 1002.

15. Vreugdenhil, A. D. and C. Blomberg, "The Constitutionof the Grignard Reagent," Recueil Des TravauxChimiues Des Pays-Bas, LXXXII (19J453

16. , "The Constitutionof the Grignard Reagent Part II," Recueil DesTravaux Chimiue Des Pays-Bas, LXII(7193T, 461.

17. Zakharkin, L. I., 0. Y. Okhlobystin, and B. N. Strunin,"Organomagnesium Compounds from Magnesium and AlkylHalides in Hydrocarbon Medium," Tetrahedron Letters,XIV (1962), 631.

18."Use of Organomagnesium Compounds for the~Synthesis ofOrganic Derivatives of Group II-V Elements in a Non-etheral Medium," Akademiia Nauk USSR. Bulletin of theAcademy of Sciences of the USSR, Division of ChemicalScience (1962),791T37

CHAPTER II

EXPERIMENTAL PROCEDURE

Materials

The magnesium metal used for the preparation of the

organomagnesium halide compounds was purchased from Fisher

Scientific Company. It was described as purified, 100-120

size magnesium metal. A highly purified sample of magnesium

metal, used in the preparation of di-n-pentylmagnesium, was

donated by the Dow Chemical Company. An impurity analysis

of this magnesium yielded the following impurities:

TABLE II

IMPURITY ANALYSIS OF MAGNESIUM

Metal Impurity Percentage

Al -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. . -. -. 0.003Ca .- .- .- .- .- .- .- .- .- .- .- .-.-.-.-.-.-.-.-.- .. - - -. . 0.01Cu . . ..-..-.-..-..-...-.... . . . . . . . 0.001

Fe . . . . . . . . . . . . . - . . . . - - . - - - - 0.0005Mn . . . -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. . 0.001Sn . . . . -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. . 0.01Zn .- .- .- .- .- .- .- .- .- .- .-.-.-.-.-.-.-.-.- .. - - -. . . 0.01

The sample was used in the form of fine turnings.

The n-pentyl halides used for the preparation of the

n-pentylmagnesium halide compounds were purchased from

Eastman Chemical Company. They were analyzed for purity by

gas chromatography and in each case were found to be>99 per

cent pure.

12

13

The benzene solvent utilized in these studies, described

as thiophene free, was purchased from Fisher Scientific Company.

Prior to use, the benzene was dried by distilling it from

lithium aluminum hydride onto molecular sieve. Other solvents

used in various applications were also purchased from Fisher

Scientific Company and treated in the same manner before use.

The beryllium chloride, obtained from Brush Beryllium

Company, was reputed to be 99.8 per cent pure. It was in a

powder form.

Preparation and Analysis of theOrganomagnesium Halides

A half mole preparation of the organomagnesium halide

compound is carried out using a five hundred milliliter,

three neck round bottom flask equipped with standard taper

24/40 ground glass joints. This is equipped with a Hirsch-

berg stirrer in a Teflon Asco stirring gland which seals

with Neoprene rubber o-rings. A 100 milliliter cylindrical

separatory funnel with pressure equalizing line is used in

one neck for addition of the organic halide. A system of a

nitrogen gas inlet connected by standard taper 24/40 joint

to another larger separatory funnel which is stacked upon

a Hopkins condenser fills the third neck of the reaction

flask. The larger separatory funnel is used to store the

solvent. The reaction flask is heated by a Glascol mantle

controlled by a rheostat.

14

The first step in the procedure for preparing these

compounds is to add the required amount of magnesium metal

to the flask, and begin stirring at a rate of approximately

one half a revolution per second. Heat and nitrogen flush

are then applied. To insure that the reaction flask is dry

it is heated to approximately 125 degrees centigrade. After

the system has cooled to a temperature described as "just

hot to touch," the organic halide and the solvent are added

to the two dropping funnels. Then a slight nitrogen pres-

sure is applied to the system.

At this point the reaction is initiated by the addition

of 5 to 10 per cent of the organic halide. After smoking

and refluxing of the excess organic halide is noted as

visual evidence of reaction, the remaining organic halide

is added dropwise. Heating is controlled by the rheostat to

the temperature described above. Addition of the organic

halide is usually completed in a time period of three to four

hours.

As the reaction nears completion, the contents of the

flask will form a "mud" consistency. At this point heating

is continued and the stirring is increased to a vigorous

rate for an additional hour. The solvent is then introduced

and the heating controlled to gain a slow reflux of the

solvent. The reflux condition is continued for another two

hours.

15

The reaction product is taken into the dry box and

transferred to a one liter bottle fitted with a 24/40

standard taper joint. Next a plug is wired into the top

of the bottle and the system is then centrifuged. This

step is essential due to the fact that the liquid phase of

the reaction mixture is so viscous that the "mud" phase

will not settle out. The centrifuging is carried out at a

speed of 2100 revolutions per minute for a period of three

to six hours. The viscosity of the solution is the deter-

mining factor for the time required to separate the two

layers. After this is accomplished the bottle is taken

back into the dry box and the liquid layer filtered through

a medium fritted filter. A water white filtrate is always

obtained for the n-pentylmagnesium chloride, bromide, and

iodide compounds. Some of the arylmagnesium halide compounds

yield pale yellow filtrates.

A competing coupling reaction takes place in this

procedure along with the organomagnesium halide compound

formation. After the reaction is completed, the removal of

the coupling product is effected by evaporating the solvent

from the filtrate by means of a vacuum pump. Throughout this

procedure heat is applied to warm the solution for ease of

evaporation. After a state of dryness has been reached, both

pumping and warming are continued for approximately a half

hour to an hour depending upon the amount of coupling product

16

found in a previous analysis. Next, benzene solvent is re-

added to the flask to bring the solid organomagnesium halide

compound back into solution. In the case of n-pentylmagnesium

compounds, only a minute amount of solid did not dissolve after

evaporation.

The coupling product found in the n-pentylmagnesium

halide system is decane. Analysis for decane is made by

gas chromatography using a fifteen foot silicone column

(SE-30) at a temperature of 120 degrees centigrade and a

helium carrier gas flow rate of one milliliter per second.

The analysis is carried out using an instrument which con-

tains a thermal conductivity detector.

In order to determine the amount of magnesium that

exists as the organomagnesium halide form, an analysis of

the purified solution is made. This is accomplished by

first determining the total hydroxide concentration produced

upon hydrolysis of an aliquot of the solution. This analysis

is made by a standard titration method using phenophthalein

indicator. An analysis of the hydrocarbon from another

hydrolyzed aliquot of the solution by gas chromatography

determines the concentration of the organic part of the

organomagnesium halide compound which was bound to the

magnesium atom. From these two analyses the yield of mag-

nesium existing as organomagnesium halide can be obtained.

To complete the analysis of this solution a determination of

17

the concentration of the halide species is made. This is

done by a potentiometric titration method from a hydrolyzed

aliquot of the solution. Standardized silver nitrate is

employed with a potentiometric analysis system consisting of

a silver--silver chloride, and a calomel electrode connected

to a voltage meter. From these analyses a stoichiometric

determination can be made of the organomagnesium halide

species existing in the benzene solvent.

Cryoscopic Molecular Weight Determination

The apparatus used in making cryoscopic measurements

on solutions of organomagnesium halide compounds in benzene

solvent is shown in Figure 1. The apparatus shown in Figure 1

consists of a piece of twenty millimeter tubing two inches

long, sealed at one end. The other end consists of an outer

24/40 standard taper ground glass joint and a side arm ex-

tending from beneath this joint. The side arm is attached to

a three way standard taper stopcock. The function of the side

arm is to admit a nitrogen atmosphere throughout the measure-

ment. A mercury filled thermowell is used to provide a thermal

contact from the solution to the thermistor. The thermistor

is connected to a Leeds and Northrup ten millivolt recorder

which serves as a null-point indicator for the thermistor

bridge. The thermistor sensitivity is 0.001 degrees centigrade.

A solvent freezing point depression may be duplicated toi0.006

degrees centigrade. The freezing point of a solution may be

THERMISTOR

ASCO GLAND

TO

SOLUTION

o

'4

18BALANCE BRIDGEAND RECORDER

NITROGEN

THREE WAYSTOPCOCK

THERMOWEL LCONTAININGMERCURY

FIGURE I. MOLECULAR WEIGHT APPARATUS

t

19

duplicated to 0.02 degrees centigrade. The thermowell is

held into the system by a Teflon Asco stirring gland which

seals the nitrogen atmosphere into the system with Neoprene

o-rings. This stirring gland also allows the thermowell to

be rotated. Glass tips welded onto the thermowell provide

agitation of the solution as the thermowell is rotated.

Better freezing point data duplication of the solvent is

aided by wrapping the outside of the apparatus with a film of

plastic insulation.

The procedure employed in making freezing point deter-

minations is to load the above described apparatus with a

sample of benzene solvent. The system is then immersed to the

level of the side arm in an ice water solution contained in a

Dewar flask. The thermowell is rotated as the bridge is con-

tinually balanced until the freezing point of the solvent is

detected. This gives a freezing point reading of the solvent

on the bridge.

Next the apparatus is cleaned and taken into the dry box

and loaded with a solution containing the organomagnesium

halide compound. The same procedure employed with the solvent

is then repeated under nitrogen atmosphere to determine a

reading for the freezing point of this solution. From these

two readings a freezing point depression can be determined

for the solution.

20

Knowing the densities of the solvent and the solution

to be equivalent, the concentration of the solution containing

the organomagnesium halide compound and the freezing point

depression produced by this solution, then, the molecular

weight of the organomagnesium halide species can be determined

from the following expression:

M2 = Kf 2 1000Tf Wi

M2 molecular weight of the solute

Kf molal freezing point constant for the solventemployed

Tf freezing point depression

w2 grams of solute

w, grams of solvent

From the data of molecular weight in the solution and the

stoichiometric molecular weight the degree of association can

be determined.

Preparation and Analysis ofDi-n-pentylmagnesium

Di-n-pentylmagnesium was prepared in the absence of

ether solvent in order that its solubility in benzene solvent

could be determined. The general procedure used in this

synthesis is first to prepare di-n-pentylmercury, and then to

carry out a metal exchange reaction between the di-n-pentylmercury

and magnesium metal in benzene solvent.

21

Di-n-pentylmercury is prepared by the action of mercuric

chloride on n-pentylmagnesium bromide in a large volume of

ether. The mercury chloride is introduced into the reaction

vessel with a Soxhlet extractor (1). After the required

amount of mercury chloride is added, a large portion of the

ether solvent is distilled away from the reaction mixture

while it is still being stirred. Upon completion of the

distillation, the ether is readded to the reaction flask.

The excess Grignard reagent is then removed by hydrolyzing

the reaction and separating the water layer from the ether

layer. Di-n-pentylmercury is recovered from the ether solution

by vacuum distillation. The conditions required to distill

the mercury compound are 139 degrees centigrade and 15.5 mm

mercury pressure.

Synthesis of the di-n-pentylmagnesium (2) consists of

stirring a solution of di-n-pentylmercury and benzene with

purified magnesium turnings. This exchange reaction's rate

can be increased by warming the reaction. As the reaction

proceeds, the solution becomes very viscous. The stirring

time required for this reaction to reach 70 per cent com-

pletion is one month, at a temperature of 35 degrees centi-

grade.

A Varian A60 nuclear magnetic resonance spectrometer is

used to monitor the extent of reaction in the synthesis of

the di-n-pentylmagnesium. Utilization of the alpha-methylene

22

triplet at delta = 1.35 ppm with respect to tetramethyl

silane standard was the primary absorption employed in

monitoring the reaction. Spectra of the starting material

and of a n-pentylmagnesium chloride preparation are used to

evaluate the limits of this reaction. After a nuclear magnetic

resonance spectrum of the reaction mixture shows little charac-

teristics of the di-n-pentylmercury spectrum the reaction is

stopped.

Obtaining a solution of di-n-pentylmagnesium from the

reaction mixture is complicated by the suspended magnesium

amalgam in the very viscous reaction solution. This reaction

solution must be filtered to eliminate the suspension; how-

ever, it cannot be diluted because of the desire to study

the solubility of the di-n-pentylmagnesium in the benzene

solvent employed. After enough of the mixture has been

filtered to enable analysis to be made, the stoichiometry

and molecular weight of the species in solution is determined

by using the same procedure described in the second section

of this chapter.

Determination of the yield of di-n-pentylmagnesium in the

solution is made in two ways. First the amount of di-n-

pentylmagnesium produced is determined by the procedures

described earlier. The other method is to determine the

actual mercury content remaining in solution by a spectro-

graphic procedure utilizing the 2536A emission of sparked

23

mercury. Densitometer readings are made of the intensities

of the lines from the spectrographic plates and from this data

an intensity-concentration graph is constructed.

Preparation and Analysis of Organo-beryllium Compounds

The apparatus used in the synthesis of the organo-

beryllium compounds consists of a round bottom flask fitted

with a Hirschberg stirrer and a Teflon Asco stirring gland.

The reaction between beryllium chloride and the organomag-

nesium halide compound is carried out by vigorously stirring

the mixture. The beryllium chloride is introduced into the

reaction flask by spatula before the stirring is begun. A

stoichiometric amount of beryllium chloride is used.

If the organomagnesium halide compound is soluble in

benzene, a solution of the organomagnesium halide compound

is stirred with the solid beryllium chloride. The ethyl-

magnesium halide compounds are only sparingly soluble in

benzene solvent; therefore, in effecting a synthesis of di-

ethylberyllium the beryllium chloride is stirred with a mix-

ture of solvent and the ethylmagnesium halide mud. The

reaction can be accomplished either in a dry box or outside

the dry box under a nitrogen atmosphere.

The stirring time required for the reaction to reach

completion is dependent upon the organoberyllium compound

being synthesized. It was observed in this work that the

24

formation of the non-aromatic organoberyllium compounds was

completed in twelve to fifteen hours whereas the aromatic

organoberyllium compounds required twenty-four to thirty hours

of stirring time. Application of heat to increase the rate

of these reactions was not used due to the instability of

the organoberyllium compounds at elevated temperatures.

Determination of the concentration of the organoberyllium

compound prepared by the described technique is made by two

methods. One method is to determine the amount of beryllium

in solution by the ring oven technique (4). The second method

is to determine the concentration of the alkyl or aryl portion

of the organoberyllium compound. This analysis is made either

by gas chromatography for the alkyl or aryl hydrocarbon species

which remain in solution upon hydrolysis or by gas volume

measurements for the alkyls which form gases upon hydrolysis.

To apply the first two analytical techniques, aliquots of the

solution containing the organoberyllium compound are pipetted

into volumetric flasks. These solutions are then hydrolyzed

and acidified. Water is added until the water layer reaches

the volumetric marking. The hydrocarbon layer is then removed

for gas chromatographic analysis. The remaining water layer

is used for the ring oven analysis. If the organoberyllium

compound being hydrolyzed contains a short chain alkyl group,

the solution is cooled in ice water before hydrolysis is car-

ried out, since shorter chain dialkylberyllium compounds

25

react very violently with water. However, if the organo-

beryllium compound contains an aryl hydrocarbon portion,

after water is added to the solution it must be shaken vig-

orously to get the beryllium into the water layer.

Diethylberyllium yields a gas composed essentially of

ethane when it is hydrolyzed. Figure 2 shows the apparatus

used to hydrolyze a solution of diethylberyllium and to

measure the volume of gas evolved. The procedure used is to

load the diethylberyllium solution into (A), the apparatus

enclosed by the dotted lines in Figure 2. This is done in

the dry box. This piece of apparatus is then brought out

and connected to the gas burette and vacuum manifold. Next

the gas burette and vacuum manifold are flushed with nitrogen

and checked for leaks. In succeeding steps the ampule con-

taining the water (B) is placed into position and the entire

system is adjusted to atmospheric pressure. Next the system

is isolated from the vacuum manifold and the gas burette.

Liquid nitrogen is used to freeze the solution containing

beryllium. After the solution is frozen the ampule containing

water is inverted and the water is added to the frozen solution.

Warming of the solution is controlled slowly until a pressure

of evolved gas is obtained. The system is then opened to the

gas burette and the volume of gas evolved is measured. Next

the solution is slowly stirred by means of a Teflon coated

magnetic stirring bar which is contained in the solution.

VACUUM.MANIFOLD

THREE WAY

WATER STOPCOCK

B

CLAMP

SOLUTION-4-

L

MERCURYLEVELINGBULB

GASBURETTE

A

HYDROLYSIS APPARATUS

26

TO NITROGEN

I

~~~

1*44mommumommomm

FIGURE 2.

27

Determination of the content of the gas evolved is made by

using gas chromatography. A fifteen foot silica gel column

is used for this analysis. The hydrocarbon portion of this

gas is detected in a stream of helium carrier gas, and the

hydrogen gas content is detected using nitrogen carrier gas.

The gas chromatograph being used is equipped with a thermal

conductivity detector.

The determination of molecular weights of the organo-

beryllium compounds is carried out in the same manner as

described for the organomagnesium halide compounds. Benzene

is used as the solvent for these organoberyllium compounds.

Infrared Absorption Studies

A Perkin-Elmer Model 21 spectrophotometer is employed

to study the absorption frequencies of the organomagnesium

halide complexes, di-n-pentylmagnesium, di-n-pentylmercury,

and organoberyllium compounds synthesized in this work. The

absorption frequencies were observed in the region between

fifteen and twenty-five microns. This required cesium bromide

optics which were used in this study.

The procedure used to obtain this data is first to flush

the spectrophotometer with nitrogen gas. A scan of cyclo-

hexane is run for calibration purposes. The absorption fre-

quency used for calibration purposes is 19.07t.02 microns (3).

Next, solutions were loaded into 0.25 millimeter path length

28

cells in the dry box. These cells were then brought out of

the dry box and spectra of the solutions obtained.

CHAPTER BIBLIOGRAPHY

1. Gilman, Henry and Robert E. Brown, "The Preparation ofMercury Dialkyls from Organomagnesium Halides," Journalof the American Chemical Society, LII (1930), 331

2. Schlenk, W., "Magnesiumdialkyle and Magnesiumdiaryle,"Berichte der Deutschen Chemischen Gesellschaft, LXIV

3. Stewart, James E., "Infrared Spectra of Solvents in thePostassium Bromide Region," Beckman Scientific andProcess Instruments Division Appicati--~s

4. West, Philip W. and Patricia R. Mohilner, "Estimationof Beryllium with Eriochrome Cyanine R Using theRing Oven Technique," Analytical Chemis XXIV(1962), 558.

29

CHAPTER III

RESULTS AND DISCUSSION

In Chapter I a summary was given of what is known about

the molecular structure of organomagnesium halide compounds

in hydrocarbon media (3) and in higher dielectric media such

as ether, tetrahydrofuran, and triethylamine (1, 2). From

this discussion it is evident that the elucidation of the

molecular structure of organomagnesium halide compounds is

more complete for the higher dielectric solvents than for

hydrocarbon solvents. Therefore, the purpose of this work

is to gain a more complete insight into the molecular structure

of the organomagnesium halide compounds which exist in hydro-

carbon solvent.

In review, Bryce-Smith and co-workers (3) determined

that the empirical formula R3MgX is representative of some

solutions of "butylmagnesium iodide" in isopropylbenzene and

tetrahydronaphthalene, although relative viscosity studies

suggested higher molecular weights. Bryce-Smith also reported

that a low degree of solubility was characteristic for the

methyl, ethyl, and n-propylmagnesium halide compounds in these

solvents. In order to secure a more complete description of

the molecular structure of the organomagnesium halide compounds

in a hydrocarbon medium, an extension of this work seems necessary.

30

31

The system chosen for study was the n-pentylmagnesium

halides in benzene solvent. Benzene was chosen as the

solvent so that molecular weight measurements could be done

cryoscopically. The n-pentylmagnesium halide compounds

were selected due to expected increase in solubility and

because they had not been studied.

The data obtained in an attempt to elucidate the

molecular structure of these n-pentyl-agnesium halide

compounds in benzene solvent is summarized in Table III.

TABLE III

ANALYSIS OF n-PENTYMAGNESIUMIN BENZENE SOLVENT

COMPOUNDS

Alkyl Halide RatioHalide Molari MolarX Association

Chloride 0.434 . . . . . 1.80.348 0.003 116 2.10.130 . . . . . 2.2

Bromide 0.255 0.0158 16.1 5.1

0.513 0.035 14.6 4.5

0.320 0.026 12.3 7.60.290 0.023 12.6 8.40.185 0.015 12.3 8.3

0.36 0.0200 18.0 5.20.244 0.0136 17.9 4.80.153 0.0084 18.2 4.1

Iodide 0.438 0.095 4.6 . .0.208 0.041 5.1 . .0.077 0.015 5.1 . .

0.580 0.118 4.9 . .

Di-n-pentyl-magnesium* 0.076 0.0007 109 2.0

*No halide species present in this compound

32

This data reports the characteristic ratio of the alkyl

to halide concentration for the species being studied, as

well as the degree of association. This is reported over a

concentration range in order to determine whether there is

any variation in the degree of association with concentration,

since this effect was noted by Ashby (1) for the organomag-

nesium halide compounds in ether solvent.

The data from Table III demonstrates that the degree of

association in benzene solvent varies only slightly upon

changing the concentration and is dependent upon the halide

species studied. This effect will be discussed in detail

for each halide in following paragraphs. The data also

gives evidence that the n-pentylmagnesium halide species

in benzene solvent are characterized by polymeric structures,

and the degree of association or polymeric character is

primarily dependent upon the halide being studied. The

degree of association decreased in the order iodide >

bromide > chloride. It is evident from the data that the

n-pentylmagnesium chloride compound in solution cannot

really be classified as an n-pentylmagnesium chloride com-

pound; it is essentially di-n-pentylmagnesium.

The solubility data in the literature indicates that

di-organomagnesium compounds are insoluble in hydrocarbon

solvents (6). Bryce-Smith (3) found di-n-butylmagnesium

to be effectively insoluble in isopropylbenzene. In order

33

to be able to explain the results observed in Table III,

di-n-pentylmagnesium must be soluble in benzene solvent.

To verify this conclusion, di-n-pentylmagnesium was synthe-

sized and yielded a very viscous benzene solution. A solution

of 0.28 normality was obtained. Therefore, it may be con-

cluded that although di-n-butylmagnesium was reported to be

insoluble in isopropylbenzene solvent, the di-n-pentylmagnesium

compound is soluble in benzene solvent.

A molecular weight study of the solution of soluble di-

n-pentylmagnesium demonstrated that this speciesexists as a

dimer in benzene solvent. This data provides conclusive

evidence that the species classified as the n-pentylmagnesium

chloride is really di-n-pentylmagnesium.

An exchange reaction between magnesium metal and di-n-

pentylmercury was employed for the synthesis of the di-n-

pentylmagnesium compound. This reaction was monitored using

a Varian A60 nuclear magnetic resonance spectrometer. This

monitoring was employed to observe the disappearance of the

alpha-methylene triplet of the di-n-pentylmercury compound.

The absorption of this alpha-methylene triplet was observed

at delta = 1.35 ppm with respect to tetramethylsilane

standard (4). Figure 3 shows NMR absorption spectra of the

reaction mixture as a function of time. The Mah absorption

(A) is an illustration of the di-n-pentylmercury absorption

pattern with tetramethylsilane as internal standard. Absorption

-2

(A) STANDARD

di-n-penty r mercury

(B) STANDARD

n-pentylmognesium

FIGURE 3. NUC

-I Pp-- (C5HII)Mg +Hg

-2 - ppmM 0

(C 5 1)2 Hg + Mg'"S o

(C)

(D)

(E) ,M~

Hxl(F)

(G)-

chloride

LEAR MAGNETIC RESONANCE MONITORING OF THEDI-N- PENT YLMAGNESIUM 'SYNTHESIS

34

I

7

DAYS

21

23

27

-30

I

35

pattern (B) demonstrates the n-pentylmagnesium chloride NMR

absorption in relation to the benzene solvent standard. Ab-

sorption patterns (C) through (G) illustrate the formation of

the di-n-pentylmagnesium compound.

The data in Table III demonstrates that the n-pentyl-

magnesium iodide compound exhibited an alkyl to halide ratio

of approximately five. This ratio remained effectively con-

stant upon dilution of the solution even though a small

amount of disproportionation was observed. These species

yielded molecular weight values greater than could be ac-

curately measured by the method applied. From the data

obtained the only conclusion that can be drawn is that the

species in solution demonstrated a higher association value

than either the n-pentylmagnesium chloride or bromide species.

The n-pentylmagnesium bromide compound in benzene

solvent demonstrated an alkyl to halide ratio magnitude which

ranged from twelve to eighteen. Table III shows that the

variation in the molecular weight values parallels the vari-

ations in alkyl to halide ratio values for the different

n-pentylmagnesiumn bromide preparations. The variation of

association upon dilution observed for these preparations

was small and also appeared to be dependent upon the alkyl to

halide ratio. In addition, there was no evidence of dispro-

portionation upon dilution as was evidenced in the n-pentyl-

magnesium iodide system. Several solutions of n-pentylmagnesium

36

bromide showed no evidence of disproportionation after stand-

ing for as long as two months.

Evidence from studies by Ashby (1) showed the chloride

to be a better bridging agent than either the bromide or

the iodide. The data demonstrated in Table III seems to

contradict such a statement. However, in order to explain

the data in Table III the following effect is proposed.

Upon preparation of the n-pentylmagnesium halide compounds

equilibrium (a) is predicted to exist; however, when solvent

is added to this preparation and the n-pentylmagnesium halide

compound goes into solution, then equilibrium (b) is estab-

lished.

(a) (RMgX) ;; MgX 2 + Rkmgk+p I"

2

(b) "RkMgk+XP" i tT "RMgq45Xs " ."RtMgt+uXu"2 2

The species (RMgX)j is an associated species formed on the

surface of the magnesium metal which is capable of dispro-

portionating to yield MgX2 and another species "RkMgk+pXp"

with a variable amount of R and X depending upon what R and X

species is being described. In solution this "RkMgk+pXp" is

capable of disproportionation into two new species represented

as "RqMg 4 5 Xs" and "RtMgttuXu." One of these species is be-

lieved to be alkyl rich and the other halide rich. Using this

proposal, the results of Table I can be explained in tID fol-

lowing manner. Since it is observed that the chloride species

37

in solution has effectively no chloride character, the

equilibrium (a) is predominantly driven to the right in

preparation. This then yields MgCl2 and the "RkMgk+pXp"

consists primarily of di-n-pentylmagnesium. However, in the

case of the bromide and the iodide species, equilibrium (a)

is not driven to the right so extensively as in the case of

the chloride, and the species represented as "RkMgk+pXp" or

(RMgX)j allows equilibrium (b) to be established.

At this point an explanation is offered for the fact that

tipon dilution, disproportionation is observed for the iodide

species and not for the bromide species in solution. The

iodide species which exist in solution exhibit a much higher

association character than the bromide species; therefore,

upon dilution equilibrium (b) is driven to the right, and for

the iodide system a higher concentration of the halide rich

species is formed. The solubility limit of the iodide rich

species is then exceeded and a precipitation is observed.

Upon disproportionation the bromide system, which exhibits a

much lower association character than the iodide system, does

not yield a very high concentration of the bromide rich species;

therefore, the solubility limit for this species is not ex-

ceeded.

The molecular structure of the Grignard reagent has been

reported (1, 2) to be dependent upon halide, organic radical,

and solvent. In an attempt to gain some insight into the

38

effect of the organic portion of the organomagnesium halide

molecular structure in benzene solvent, the data in Table IV

was obtained.

TABLE IV

MOLECULAR STRUCTURE DEPENDENCE UPON THE ORGANICPORTIONS OF ORGANOMAGNESIUM HALIDE

COMPOUNDS IN BENZENE SOLVENT

Organic Halide ~Organic (moles/ Halide (moles/ Ratio Associ-Species liter) Species liter) ation

Tolyl 0.100 Chloride 0.02 5 1.8

Phenyl 0.150 Chloride 0.011 14 0.8

n-Pentyl* 0.348 Chloride 0.003 100 2.1

Ethyl** . . . . .

*This data from Table III

**Not soluble in benzene solvent

This data, although not a complete study, provides

evidence that the organic portion of the organomagnesium

halide compound in benzene solvent has a very definite ef-

fect upon the molecular structure. The arylmagnesium chloride

compounds studied demonstrate that the species in solution can-

not be described as a diorganomagnesium compound as was ob-

served for the n-pentylmagnesium chloride compound. Table IV

also demonstrates that the ethylmagnesium halide compounds

are not soluble in benzene solvent. Therefore, the effect of

39

the organic portion of the organomagnesium halide compounds

upon the molecular structure seems evident.

The synthesis of organoberyllium compounds from organo-

magnesium halide compounds in benzene solvent proved to be

an effective method. Table V tabulates the data obtained

using this method for synthesizing organoberyllium compounds.

Data obtained in association studies is also included in this

table.

The reason for the low yield exhibited by the diethyl-

beryllium preparation is explained by the fact that ethyl-

magnesium iodide has proved to be a very difficult compound

to prepare in a high yield. Furthermore, since ethylmagnesium

halides are only slightly soluble, the reaction between beryl-

lium chloride and the "mud" from the preparation of ethyl-

magnesium iodide is characterized as a reaction between two

solid phases, and would be expected to occur with difficulty.

This effect is also demonstrated in the low yield obtained

for the di-n-butylberyllium preparation. The synthesis of

ditolylberyllium is a reaction carried out between solid

beryllium chloride and a solution of tolylmagnesium chloride,

and this reaction readily gives high yields. The data of

Table V demonstrates that the preparation of organoberyllium

compounds by this method is more effective for organomagnesium

halide species which are soluble in benzene solvent. The data

also reveals that the organoberyllium compounds characterized

0

'H

( 10

01co02

C\J0

**

. H

**

*4O Lrn 0 LIT 0 (\

H ,

OH0 -- 0 Ln\ : C4 J+, C\, n \j C-) co C\J

Hc H-Hr-H4 0 C)H

0000

So cem 2~CMiCM Hc H GD H . C.to L5 .0t r..aSH' [oC H 00 -it

0

0

0C)

5,'

H

H

40

-HH

H-H

' 0 H

-P P o0 o0 H

H H0I I H 0z 0 4I I +e a

.*H .H .*- .rHq q q q

I

40

CD

co0H(OH0COO

pq

r400

H c;

O 0

HO

-H

.r-

4

0

0

rd

C

ra

coaQ)

0

CH

'H

0

A r

--

H4c

0

rH

-P

ao0

.P

0

02

.S

02

0cH

0

0P4

02I

41

by large organic species exist as monomers in benzene

solvent.

The data obtained from the infrared absorption studies

of the compounds synthesized is tabulated in Table VI. An

illustration of the absorption spectra for the n-pentyl-

magnesium halide compounds and di-n-pentylmagnesium is

shown in Figure 4. In view of the comparatively low halide

content of these solutions, the similarity of their spectra

in this twenty micron region is not surprising. As can be

seen in Figure 4, the shapes of the absorptions did appear

to broaden as the halide content increased in the order

Cl Br I.

The infrared absorption data reported in Table VI

was obtained for solutions of these compounds in benzene

solvent. The characteristic C-Ig-C absorption was observed

between 545 and 550 wave numbers. This represents a shift

to higher frequencies of thirty wave numbers compared to

diethylmagnesium in diethyl ether (7). This shift may be

interpreted in terms of a more polar carbon-metal bond in

strongly coordinating solvents (8). This effect is also

seen from the data in Table VI in the absorption shifts

measured by n-pentyl, tolyl, and phenyl compounds. The

C-Hg-C absorption is reported to demonstrate additional

evidence that the di-n-pentylmagnesium preparation formed

WAVE NUMBER (cm-1)

550 500

III

421450

(C 5 HII )2 Mg0.077 N

0.25 N

"Br "

O.I5 N

"I "I

0.23 N

I I15 17 19 21

WAVE LENGTH (microns)

FIGURE 4q INFRARED SPECTRA OF -PENTYLMAGNESIUM HALIDE COMPLEXESIN BENZENE

23

600

wz

Ul)z

I

43

TABLE VI

INFRARED ABSORPTIONS

Compound Absorption (cm-1 )

n-pentylmagnesium iodide . . . . . . . . . . . . . 545n-pentylmagnesium bromide . ...... . . . . 547n-pentylmagnesium chloride . . . . . . . . . . . . 548di-n-pentylmagnesium . . . . . . . . . . . . . .0.*549di-n-pentylmercury . . . . . . . . . . . . . . . 515phenylmagnesium chloride . . . . . . . . . . . . . 430tolylmagnesium chloride . . . . . . . . . . . . . 549

484*diethylberyllium . . . . . . . . . . . . . . . . . 505

di-tolylberyllium . . . . . . . . . . . . . . . . 502

465*diphenylberyllium . . . . . . . . . . . . . . . . 442

*This absorption is a characteristic absorption ofthe tolyl portion of the species reported.

a new species which can be characterized by infrared

spectroscopy to exhibit the C-Mg-C absorption frequency.

The infrared absorption frequencies for the organoberyllium

compounds were observed in the range of 500 to 505 wave

numbers.

According to the harmonic oscillator approximation the

infrared absorption frequencies would increase in the order

C-Hg-C < C-Mg-C ( C-Be-C if mass effects predominated.

Table VII gives values of masses and electronegativity values

(5) for the elements concerned. The force constants in the

harmonic oscillator approximation will be affected by a change

in electronegativity values for each element. The greater

the attraction between a metal element and an organic radical,

44

TABLE VII

ELECTRO\EGATIVITY AND MASS VALUES

Element Mass (grams/moles) Electronegativity

Be 9.0 1.47

Mg 24.3 1.23

Hg 200.6 1.44

the larger the force constant value will be. This effect

must be large enough to explain the order of absorption

frequencies observed in Table VI. This order of absorption

frequency values is seen to be C-Mg-C > PC-Hg-C > C-Be-C.

CHAPTER BIBLIOGRAPHY

1. Ashby, E. C., "Proof for the RMgX Composition ofGrignard Compounds in Diethyl Ether. RMgX, theInitial Species Formed in the Reaction of RX andMg," Journal of the American Chemical Society,LXXXVII (1965T, 279.

2. Ashby, Eugene C. and Martin B. Smith, "Concerning theStructure of the Grignard Reagent. III. In DiethylEther. Relevance of Grignard Composition to theMechanism of Addition to Ketones," Journal of theAmerican Chemical Society, LXXXVI (1964,"433.

3. Bryce-Smith, D. and G. F. Cox, "Organometallic Compoundsof Group II. Part III. Unsolvated OrganomagnesiumHalides," Journal of the Chemical Society (1961), 1175.

4. Dessy, Raymond E., T. J. Flautt, H. H. Jaffe, and G. F.Reynolds, "Nuclear Magnetic Resonance Spectra of SomeDialkylmercury Compounds," Journal of Chemical Physics,XXX (1959), 1422.

5. Rochow, Eugene G., Organometallic Chemistry, New York,Reinhold Publishing Corporation, 1964.

6. Rochow, Eugene G., Dallas T. Hurd, and Richard N. Lewis,The Chemistry of Organometallic Compounds, New York,John Wiley and Son, Inc., 1957.

7. Salinger, R. M. and H. S. Mosher, "Infrared SpectralStudies of Grignard Solutions," Journal of the AmericanChemical Society, LXXXVI (1964), 1782.

8. West, Robert and William Glaze, "The Infrared Spectraof Alkyllithium Compounds," Journal of the AmericanChemical Society, LXXXIII (1l61),3758.

45

BIBLIOGRAPHY

Books

Coates, G. E., Organo-Metallic Compounds, London, Methuenand Company Ltd., 95.

Rochow, Eugene G., Organometallic Chemistry, New York,Reinhold Publishing Corporation, 1964.

Rochow, Eugene G., Dallas T. Hurd, and Richard N. Lewis,The Chemistry of Organometallic Compounds, New York,John Wiley and Son, Inc., 1957.

Articles

Ashby, E. C. and W. E. Becker, "Concerning the Structure ofthe Grignard Reagent " Journal of the American ChemicalSociety, LXXXV (19631, 118.

Ashby, Eugene C. and Martin B. Smith, "Concerning the Structureof the Grignard Reagent. II. In Diethyl Ether. Relevanceof Grignard Composition to the Mechanism of Addition toKetones," Journal of the American Chemical Society,LXXXVI (1964)7,4363Y

, "Concerning the Structureof the Grignard Reagent. --III. In Diethyl Ether. Relevanceof Grignard Composition to the Mechanism of Addition toKetones " Journal of the American Chemical Society,LXXXVI 1964)7, 4363T

Ashby, E. C., "Proof for the RMgX Composition of GrignardCompounds in Diethyl Ether. RMgX, the Initial SpeciesFormed in the Reaction of RX and Mg " Journal of theAmerican Chemical Society, LXXXVII 41965),O2509.

Bryce-Smith, D., "Unsolvated Organomagnesium Complexes,"Bulletin de la Societe Chimique de France, VII (1963),

Bryce-Smith, D. and G. F. Cox, "Organometallic Compounds ofGroup II. Part III. Unsolvated Organomagnesium Halides,"Journal of the Chemical Society (1961), 1175.

46

47

Coates, G. E. and F. Glockling, "Diisopropylberyllium andSome Beryllium Hydrides," Journal of the Chemical Sociey(1954), 22.

Dessy, Raymond E., T. J. Flautt, H. H. Jaffe, and G. F. Reynolds,"Nuclear Magnetic Resonance Spectra of Some DialkylmercuryCompounds," Journal of Chemical Physics, XXX (1959), 1422.

Dessy, R. E. and George S. Handler, "The Constitution of theGrignard Reagent," Journal of the American Chemical yLXXX (1958), 5826.

Dessy, R. E., G. S. Handler, J. H. Wotiz, and C. A. Hollings-worth, "The Constitution of the Grignard Reagent,"Journal of the American Chemical Society, LXXXIX (1957),3476.

Gilman, Henry and Robert E. Brown, "The Preparation of MercuryDialkyls from Organomagnesium Halides," Journal of theAmerican Chemical Society, LII (1930)9, .3314.T

Grignard, V., "Sur les combinaisons organmagnesiennes mixteset leur application a des syntheses d'acides, d'alcoolset d'hydrocarbures," Annales de Chimie, XXIV (1901), 433.

Jolibois, M. Pierre, "Sur la formule du derive organo-magnesienet sur l'hydrure de magnesium," Comptes Rendus Hebdomadairesdes Seances, CLV (1912), 353.

Salinger, R. M. and H. S. Mosher, "Infrared Spectral Studiesof Grignard Solutions "1 Journal of the American ChemicalSociety, LXXXVI (1964 , 1782.

Schlenk, W., "Magnesiumdialkyle and Magnesiumdiaryle,"Berichte .der Deutschen Chemischen Gesellschaft, LXIV

Snow, A. I. and R. E. Rundle, "The Structure of Dimethylberyllium,Acta Crystallogaphic, LV (1950), 348.

Stucky, G. D. and R. E. Rundle, "The Structure of Phenyl-magnesium Bromide Dietherate and the Nature of GrignardReagents," Journal of the American Chemical SLXXXV (1963)t 1002.

Vreugdenhil, A. D. and C. Blomberg, "The Constitution of theGrignard Reagent," Recueil Des Travaux Chimiques Des

ys-Bas, LXXXII (193)TT53.

48

Vreugdenhil, A. D. and C. Blomberg, "The Constitution of theGrignard Reagent. Part II," Recueil Des Travaux ChimiquesDes Pays-Bas, LXXXII (1963), 41.

West, Philip W. and Patricia R. Mohilner, "Estimation ofBeryllium with Eriochrome Cyanine R Using the Ring OvenTechnique," Analytical Chemistry, XXXIV (1962), 558.

West, Robert and William Glaze, "The Infrared Spectra ofAlkyllithium Compounds " Journal of the American ChemicalSociety, LXXXIII (19613, 35.

Zakharkin, L. I., 0. Y. Okhlobystin, and B. N. Strunin,"Organomagnesium Compounds from Magnesium and AlkylHalides in Hydrocarbon Medium," Tetrahedron Letters,XIV (1962), 631.

, fUseof Organomagnesium Compounds for the yntesis 0 OrganicDerivatives of Group II-V Elements in a NonetheralMedium," Akademiia Nauk USSR. Bulletin of the Academyof Sciences of the USS, Division of emcT'T~ScienceTT962) 1913.

Reports

Stewart, James E., "Infrared Spectra of Solvents in thePotassium Bromide Region," Beckman Scientific and ProcessInstruments Division A pplicationata SheetFullerton, California,-Beckman Instruments, Inc.