U. S. Department of Commerce National Bureau of Standards

Research Paper RP2088 Volume 44, April 1950

Part of the Journal of Research of the National Bureau of Standards

Separation of 2,3-Dimethylpentane, 1,cis-3-Dimethyl­cyclopentane, and 3-Ethylpentane from Petroleum 1

By Augustus R. Glasgow, Jr., Charles B. Willingham, and Frederick D. Rossini

This report describes the separation of 3-ethylpentane and the fractionation of 2,3-

dimethylpentane and l ,cis-3-dimethylcyclopentane from the aromatic-free fraction of

petroleum normally boiling in t he range 89° to 94° C. These three compounds, together

with t he four h ydrocarbon compounds previously separated, constitute substantially all of

t he material of this fraction of petroleum . For t hese seven compounds, the normal boiling

points (of high-puri ty samples not from the prescnt investigation) and t he estimated am ounts

by volume in t he original Ponca, Oklahoma, crude petroleum are as follows: 2,3-dimethyl­

pentane, 89.78° C, 0.1 percent; 2-methylhexan e, 90 .05° C, 0.7 percent ; 1,trans-3-dimethyl­

cyclopentan c, 90.77° C, 0.9 percen t ; l ,cis-3-dimethylcyclopcntane, 91.72° C, 0.2 percent;

3-m ethylhexane, 91.85° C, 0.5 pcrccnt ; l,trans-2-dimethylcyclopentane, 91.87° C, 0.5 per­

cen t; and 3-ethylpentane, 93 .47° C, 0.05 percent.

1. Introduction

As part of the work of the API R esearch Proj ect 6 at the National Bureau of Standards on the fractionation and analysis of hydrocarbons in petrolewn [I, 2],2 the program has been compleLed on that part of pe t roleum normally boiling between 89° and 94 °C. In earlier work [3, 4], 2-methyl­hexane, 1,trans-3-dimethylcyclopentane, 1,tmns-2-dimethylcyclopentane, and 3-m ethylhexane were separated from this fraction , and in the present in­vestigation 2,3-dimethylpentane, 1,cis-3-dimethyl­cyclopentane, and 3-ethylpentane have been determined.3 This report describes the fractiona­tion of the latter three hydrocarbons and gives the estimated amounts of all seven hydrocarbon components that comprise the aromatic-free frac­tion of petroleum normally boiling in the range 89° to 94 ° C .

II. Material Analyzed

The API Research Proj ect 6 at the National Bureau of Standards has had under investigation

1 Tbis investigation was performed as part of tbe work of tbe American Petroleum Institute Researcb Project 6 a t the National Bureau of Standards OJ) the "Analysis, Purificat ion, and Properties of H ydrocarbons."

2 Fignres in brackets indicate tbe literature referenees at tbe end of this paper.

S See reference [.5] for tbe naming of geometric isomers of the polyalkyl cycloparaflins.

Hydrocarbons From Petroleum

since 1928 a large quanti ty of a represen tative petroleum taken from a well at Ponca, Okla. [1, 2, 6]. All of the material from the original p etroleum normally boiling between 9 ° and 94 ° C remaining after the previous treatment [3, 4, 7] was blended together for analysis, with the excep­tion of small lo ts of approximately 50 ml each of the best samples of 2-methylhexane, 1,trans-3-dimethylcyclopentane, 1,trans-2-dimethylcyclo­pentane, and 3-m ethylhexane separated in the previous processing [3, 4]. B efore the beginning of the present investigation, the material was again fil tered through silica gel [8] to remove traces of toluene and produce a mixture containing only paraffins and cycloparaffins.

III. Method of Analysis and Results

This blend of material normally boiling between 89° and 94 ° C was distilled analytically at high efficiency. Following the initial distillation shown in figure 1, parts A, B, C, and D of the distillate were further processed to fractionate 2,3-dimethyl­pentane, 1 ,cis· 3-dimethylcyclopentane, and 3-ethylpentane, as listed in table 1. R eference [9] gives a description of the distilling columns used .

411

-' >-94 I

0-W

" i5

93 X\J-

;; 92 ~ I j " " "' W

'" Z ~ ;: 0-

" ~ 0-m

90

" ~ ,; " i5

89 '" N

::I(~ 0

86 •

II-A

850

w z

~ ;: w

"

X

-' >-I

-' 0-

-' >- w >- I " ~

0- 0 W

" '" " i5 i5

'" ,;, X\} Xv X\T-

nD j

~o 0

BP 0

PONCA. OKLA .. PETROLEUM

AROMATIC-FREE FRACTION. 89° TO 94° C

2:25 OF PURE COMPOUNDS 0 8P }

X no

c· - -11--

W Z ;:

I ~.

?

~ w

:5 '" >- 0 I

~

" '"

0

X

X

r--------C---------~~_1

800 !200 16 00 2000 24 00 28 00 3200 VOLUME IN ML

FIG URE 1. Distillation of the 89 0 to 94 0 C (aromatic-free) fraction of petmZeum_

1.41

0 c ..;

1.40 '" '" !;i x ~ ,; w

" 1.39 0-'-' " ~ a:

1.38

3600

The ordinate seale on the right gives the refract ive indices of th e fractions of d ist illate, and the ordinate sca le on the left gives t he boiling point of the dist illate at 725 mm JIg. The scale of abscissas gives the volume of distillate in mil lili ters. The portions A to D , enclosed wit b arrows. were redistilled . The distillate fraction, C', was ana lyzed by spectrographic infrared absorption measurements. t he resulLs of which are given in table 2.

412

56,-----,-----,----,,----,-----,-----,-----,-----,-----,-----,

r;-55 l< ~

53

.... z w a.

° -' <..> >­<..> .J >­I

:;; " o

w Z

" .... z w a. .J >­I .... W

" o "'-

A---j

2.3 - DIMETHYLPENTANE

CONCENTRATE

I BP

w X n O~ OF PURE COMPOUNDS ~

w I -' >­:c ....

nO (regular ) ~ - - - -, _ _ _______________ r __ J ____ ___ r _______ _ _____ _ _ __ ___ _ _____ :'_

1 no (ozeolropic ) x

VOLUME IN ML

/ .J >-w IZ .... " W .... ~z ow .0. ",0

.J ~<..> c>-~t)

V;

1.42

1. 4 1

0 c

<.i

"' '" .... "

1.40 ~ 0 ;;;

w > >= <..>

" a: "-w a:

1.39

FIGU RE 2. Distillation of the 2,3-dimethyZpentane concentrate (part B, fig- 1)_

The ordinate seale on the light gives the reo, fmeti ve indices of the hydrocarbon portion of the fractions of a'eotropic d ist illate, and t he ordinate scale on the left gives the boiling point of the azeotropie dist illate at 725 mm JIg. The scale of abscissas gives the volnme of the hydrocarbon portion of the distillate in milliliters. The por­tion AI enclosed with arrows, was redist illed. 'rhe broke n eUl've refers to the previous distri ­but ion of tho refractive index of t his material in the regular distillation (shown by part B 0 f fig. 1) •

Journal of Research

T A BLE 1. Informati on on the disti llation fo r the analysis and separation of 2,3-dimethylpentane, 1,cis-3-dimethylcyclopentane, and 3-ethylpentane fTO m the arol1wtic-free /Taction of petroleum n01'mally boi ling in the range 89° to 94° C.

Distillation

I ~ \I mber Dis- of equi va- Vol-M aterial t ill- len t R eflu x R ate P ressure umc Volume Re·

i ng a t heoretical ratio of col- of dis- K ind of A zeotrope·fo rming of of each suits col- plates (approx i- lection t illat ion distillation ;~~s;~Sn;~J~f,~~ed, hydro· fraction plotted

u rnn at total mately) of dis- (con- carbon of dis- in n u m- reflnx tillate trolled ) charged t illate figure

ber (approx i-mately)

------------ --- ----- ---------- ------- - -

84° to 94° C (aro matic-free) fraction of petroleum .

2,3·Di met h y l pe nt a n e concentrate (par t B , fi g. 1).

2,3·Di mct h y l pe n ta n e conccntmte (part A , figs. I a nd 2).

1 ,cis-3-Di mcth y lcyclo pcntanc co nco ll -trate (par t C, fi g. I).

1 ,cis-3-D i methylcyclopentanc cO ll ce n-

trate (part A, fi g. 4) . 3·Etbylpenta ne concentrate (part D,

fig. I ) . 3-Ethy lpentane concentra te (part A ,

fig. 6) .

• For fur ther details, sec reference [9J. b Same as column 4 in reference [9J.

b3A

l A

lA

lA

lA

lA

l A

ml/hr 200 190/ 1 4.2

150 270/ 1 1. 1

150 270/ 1 1. 1

150 200/ 1 1. 5

150 150/1 0.5

150 300/1 1.0

150 300/1 1.0

2,3-Dimethylpentane was fractionated by azeo­tropic distillation with methanol followed by regular dis tilla tion, the results of which arc shown in figures 2 and 3. In the azeotropi c distillation, the methanol, which comprised abou t 40 percent by volume of the distillate, was extracted from the hydrocarbon portion by three cold water extrac­t ions in a separatory funnel. The best lot from the distilla te shown in figure 3 was sel ected on the

mrn [-fg ml ml 725 Hegular _____ .... --.- --- -- - .-. -------- 3.530 17 1

725 A zcotrop ic . _____ :r.letha nol, 700 mL __ 550 12 2

725 Hegular. ._ ... _._ - ---- - -- - ----- -------- 235 12 3

i25 Azcotrop ic ... _ .. Mct hanol, 750 m L _. 878 II 4

54 R eglllar _ . ___ . _._ ---- - -- ---- - ---- ------ 202 13 5

i25 ___ .. do_._. ___ ._._ ----- - -- -- ------------ 198 7 6

725 Azeotropie Methanol, 1.\0 m l 40 6 7

basis of boiling point and refractive index as having the highest concentra tion of 2,3-dimethyl­pentane. This frac tion was examined by spectro­graphic infrared absorp tion m easurements by the Humble Gil and R efining Company, Houston , T exas, and found to contain 57 percent by volume of 2,3-dimethylpentane. Th e results arc given in t able 2.

T A B LE 2. R esults of the spectrographic infmred absorption measw'ements ". b of selected samples from the aromatic-free fraction of P onca, Oklahoma, petroleum normally boiling in the mnge 89° to 94° C

3 3. ] , 1· 2 3- 11, trans.3- 1 1, cis-3· I, trans-2· ' Dim'et h yl- D imethyl- DimCLh '1- 2-M eth YI" ID imeLh YI- IDim eLhYI' 3-Methyl- D imethyl· 3·Eth yl· n·llep­

tane

Methyl­cyelo­hexane Identificat ion of sample

penta ne oyolo- pcn tan~ hexane oyolo- oyolo- hexane oyolo- pentane pentane pentane pentane pentane

P ercentagE' by \'olume in Lhe sa mple --------------!----.----,---...,.----,-------------,,--

Part C': figure 1 b __ . ____ . ________ _____ __ . __________ __ • __ _________ ..

2,3·Di met h ylpen tane; figure 3 n ___ . _____ .__ ___ I 57 Part A'; figure 4 a ____________________________ . __________ __________ _

Part B; fig ure 4 n . _______ . __ . __ ... _ ._ .. _ ... _. ___ .. _._. __ . ______ _ . __

Part C; fig ure 4 n . ___ __ ______ . ____ ._. ___ . __ ._ .... ___ .. ___________ ._

Part D ; fig ure 4 s. _____ . _ . _____ ... _ ___ . ___ ._._ . __ ._._ .... __

Part A; fig ll re5 B . __ • ___________ _ __ .. _._._._. __ ... _ ... __ ._.

Part B; fig ure 5 B ___ • __ ._ .. _. ______ .. ___ ._._._ • ____ ....... _

Part C; figure 5 B . __ ._ .. _ .. _________ • __ ._._._ • ____ • ___ .. ..

3.Ethylpen tan e; figure 7 B .. ._. __ . __ ._._. _________ .. __

2

37 o o o

o 4 19 2 8 o

15 2

21 2.1 21

43 51 :1 1

o

37 o

54 42 19

10 30

0.4

B Made by the Ilumble Oi l & Refilli ng Co., Baylown, T ex. A descr iption or t he apparat us is given in rderellce [10].

39 ____ . _____ ._ .. __________ . ____ _

22 . ___ . ____ ... _____ . ___ . _______ _ 32 ._. ______ .. _ ... ______________ _ 58 .. __ .. __ ... ___ ._. ___ .. _____ __ _

92 . _________ ._ ... __ .. __ . _______ _

25 29 32 _________ .. ___ ._ ... __ . _______ _

0.8 98.7 0

b Made by the Socony· Vacuum LaboraLories, Pallls boro, N. J. A description of the apparatus is given in reference [n J.

Hydrocarbons From Petroleum 413

92 .-____ .-____ -, ______ ,-____ ,-____ -, ______ ,-____ ,-____ -, ____ -,,-__ --, 1.42

91

90

<0 56.2 I

:>

" '" OJ

"" 5b.1 ~ <t

"-~

~ 56.0

;:: UJ 0:

" ~ <t 0:

'" a. :> "' ~

0

'UJ -'z >-<t I~ ~z UJUJ :>"--0 UJ

~d z <t .>- ~ X\J C} z UJ "-

UJ Z <t x UJ I .J ,..

1.41

F I GURE 3. Distillation of the 2,3-dimethyl pen tane concent1'aie (part A, figs. 1 and 2).

-' >-I ~ UJ

~

" '" OJ

:r: ~ w :> OJ

o

2 .3 - DIMETHYL PENT ANE CONCENTRATE

o 8P72,}

X nd' OF PURE COMPOUNDS

VOLUME IN ML

3- METHYLHEXANE---z-..

X '------v-----'

RESIDUE

1.40

1.39

1.38

" c

<.5 :;., OJ

~ <t

x w

" '" UJ

~ ~ <.> <t

E UJ 0:

T be ordinate scale on tbe rigb t gives tbe reo fracti ve indices of tbe fractions of distillate, and tbe ordinate scale on tbe left gives the boiling point of the distillate at 725 m m Hg. T he scale of abscissas gives t be volume of distillate in milliliters. Tbe port ion labeled "best lot" was analyzed by spectrograpbic infrared absorption measmements, tbe result~ of wbich are given iu table 2.

100

80

UJ :> ::> .J

60 0 > ,.. CD

W <.?

40 <t ~ Z w C} 0: W a.

20 I. frans' 2' DIMETHYLCYCLOPENTANE-..........~~===----...... ,.....-------_..:::".~

I. cis' 3 - DIMETHYLCYCLOPENTANE ~

I, frons - 3-DIMETHYLCYCLOPENT ANE

I, cis - 3 - DI METHYLCYCLOPENT ANE

-II­Ii.

CONCENTRATE

VOLUME IN ML

-lI­D

o AMOUNT OF COMPONENT IN DISTILLATE FRACTION

FIGURE 4. Distillation of the 1,cis-3-dimethylcyclopentane concentrate (part C, fig. 1).

0

'" OJ

~ <t

X w o ;::

1.40 w 20 ~ <.> <t

E w 0:

The ordinatcs on the rigbt give, on tbe lower scale, tbe refractive indices of the hydrocarbon portion of the fract ions of azeotropic distillate and, on the npper scale, the percentage by volume of tbe components in tbe bydro$rbon portion of tbe distillate, as determined by spectrograpbic infrared absorption measure· ments on fractions labclcd A', B, C, and D in tbe figme. Tbese results are given numerically in tablc 2 and grapbically in tbe npper portion of tbe figure. The ordinate scale on tbe left gives tbe boiling point of tbe azeotropic distillate at 725 mm Hg. Tbe scale of abscissas gives tbe volume of the bydrocarbon portion of tbe distillate in milliliters. Tbe portion A, enclosed witb arrows, was redist illed.

414 Journal of Research

The following conclusions may be drawn from the results of the processing of the 2,3-dimethyl­pentane concentrates: (a) The regular distillation shown in figure 1 substantially separated the components normally boiling neal' 92° C from 2,3-dimethylpentane and 2-methylhexane nor­mally boiling near 90° C; (b) azeotropic distilla­tion with methanol was effective in fmther sepa­rating 1, I-dime thylcyclopen tane and l,trans-3-dimethylcyclopentane from 2,3-dimethylpentane and 2-methylhexane, as shown in figure 2; (c) the regular distillation following the azeotropic dis­tillation fmther improved the 2,3-dimethylpen tane concentrate with additional removal of lower­boiling l,l-dimethyleyclopentane, as shown in figme 3; (d) regular and azeotropic distillation at 725 mm Hg effects only a partial separation of the two paraffins, 2,3-dimethylpentane and 2-methyl­hexane. However, r egular distillation at reduced pressme should produce a more effective sepa­ration because of the increased difference (ap­proximately 1 deg C) in the boiling points [12] of the two isomer at lower pressmes (30 to 50 mm Hg).

Following the regular distillation shown in figme 1, I ,cis-3-dimethylcyclopentane II-as frac­tionated from the components normally boiling near 92 ° C by azeotropic distillation with methanol followed by r egular distillation at a redu ced pres­sure of 54 mm Hg. The results arc shown in figmes 4 and 5. Part B of the distillate shown in figme 5 contained the highest concentration of l,cis-3-dimethylcyclopentane. This portion was examined by spectrographic infrared absorption measm ements by the Humble Oil and Refining Company, Houston, Texas, and found to contain 51 percent by volume of l ,cis-3-dimethylcyclo­pentane. The r esul ts are given in table 2.

The following conclusions may be drawn from the processing of the material normally boiling near 92 ° C with respect to the separation of 1 ,cis-3-dimethylcyclopen tane : (a) Azeotropic distilla­tion with methanol , as shown in figme 4 and table 2, produces an appreciable separation in the two dimethylcyclopentanes, one from the other , re­sulting in a nine-fold change in the composition of the two isomers in the distillate, as well as effec­tively removing 3-methylhexane from l ,trans-2-dimethylcyclopentane; (b) the regular distilla tion at a pressure of 54 mm H g, as shown in figure 5, effectively removes th e 3-methylhexane from the

Hydrocarbons From Petroleum

cycloparaffins because of the greater difference in the boiling points [4 , 12] at the reduced pres ure between the paraffin, 3-methylhexane, and the cycloparaffins, l,cis-3-dimethyleyclopentane and I ,trans-2-dimethyleyclopentane.

3-Ethylpen tane was separated from the undis­tilled portion, D, in figure I, by regular distillation followed by azeotropic distilla tion with methanol. The results are shown in figures 6 and 7, respec­tively. The best lot from the distillate shown in figure 7 was selected on the basis of boiling point and refractive index as having the highest concen­tration of 3-ethylpentane. This lot was examined by spectographic infrared absorption measure­mcnts by the Humble Oil and Refining Co. , Bay­to wn, T ex. , and found to contain 98.7 pereent by volume of 3-ethylpentane. The results are given in table 2.

The following conclusion may be drawn from the processing of the 3-e thylpentan e concentrates : (a) This compound, which oceul'S in small amount in petroleum, is easily separated by regular and azeotropic distillation.

IV. Amounts in the Crude Petroleum

The calculation of the amounts by volume of the seven compounds in the aromatic-free fraction of Ponca, Okla., petroleum., normally boiling between 89 ° and 94 ° C, was made using the data from the analysis of seven representative crude petroleums [13, 14, 15] supplemented by the results of the present inves tigation, including the spectrographic infrared absorption measurements on selected fractions as listed in table 2.

The spectrographic data served to establish the relative amounts of I,cis-3-dimethylcyclopentane and I ,trans-2-dimethylc:yclopentane, and of 2,3-dimethylpentane and 2-methylhexane. The data on boiling point and refractive index as a function of volume of distillate were utilized to the full est extent of their precision by plotting the data on expanded scales of t emperature, r efractive index, and volume for usc in the calculation of the amounts of the individual components as described in rcier ence [16] .

The ra tios of 2,3-dimethylpentane to 2-methyl­hexane and of I ,cis-3-dimethylcyclopentane to I ,tmns-2-dimethylcyclopentane found in the pres­ent investigation are considered to be representa­tive of the original petroleum on the assumption

415

'" I

:> :>

" "' t-

'" "-!'! P ~

w <r :::> t-

'" <r w "-

§

w -' z >-<1 93 1. 4 3 It-

22

21

'w t-Z 0, <3 -'z ww

T I >-", :> "-It- 03 " t- z '<.) " Ww N>- '<- BP54 (distillation) :>"-

~u 0 0 60 ~ "-,-, a: ~ ",u m

,>- m <I ~U <I t-

~.~02 / BP760 (Cott rell) 1 <1

-.l "- 92 1.4 2 ..,/0, ___ 0 2 O- m

3 -' 0, T ~ 0 <r c t-

U I. cis' 3- DIMETHYLCYCLOPENTANE

t-0 ~ on

CONCENTRATE N

P t-

X2 '" 9 1 1. 4 1 <1

X, W x W

<r 0 :::>

'" t-20 <1 w

i-A- I- B- I- c- i5 i: "- t-~ '-'

'" t- E 90 1. 40 W <r

19

18

1.39 ° BP"} o BP'GO OF PURE COMPOUNDS

X ncr'

~0----~----~~--~----~~----L---~~·----~--~~----~--~~~--- 1. 38

VOLUME IN ML

92 r---r---'--~----r-----,----,-----'-----'-----r----'

~ 91 ::;; ::;;

'" N '-t-<t

a. ID

f' 90

,,; UJ

'" :::> t­<t

'" UJ a. ::;; ~ 89

UJ -' z >-<{ I t-

~ ~ . t- z W UJ

UJ >-<{ :> 0. If-- -0 Z t-z 0-, <t Ww 'U x :> 0. N>- w

~3 u I

~ -' "'u c >-.>- 0 I ~u t-'w W

.: :> X ,;.,

X 0 0

° I BP

nD j

I

I , /

/

/~ ,­I '0

/ i" o o 0.

~ ><

3

_- - 0 -w Z <{ t­Z W "­-' ~ I t­W

'"

W :::> o Vi W <r

3-ETHYLPENTANE CONCENTRATE

o BP'25} _ X n6' OF PURE COMPOUNDS X

1.42

o c o

1.4 I If) N

r­<{

x "' o

" w > >=

1.40 u <1 cr :~ a.

1.39

880.\-----.L.----+.:------L--~~""----L------,k------...L----.,.hc_---L----__",,!25

VOLU ME IN ML

416

FI GURE 5. Di stillation of the 1,cis-3-dimethylcyclopentane concentrate (part A, fi g· 4) .

Tile ordinates on the right give, on the outer scale, the refractive iJldiccs and , on the inner scale, t he Cot trell boiling points at i60 lll ll ' R g of the fractions of the distillate. The ordinate scale on the left gives the boiling point of t he di stillate at 54 mm Hg. The scale of abscissas gives the volume of distillate in millil iters. The portions A, B , and Ct enclosed with arrows, we re analyzed by spectrographi c infrared ab-sorption measurements, the results of which are given in table 2. 'rhe uwnbers accompan yin g the boiling point and refract ive index values shown in th e figure refer to the followin g: (1) to 1,cis-3·dilllet hylcyclopentane, (2) to 1,trans·2-d imethy1cyclopentanc, a.nd (3) to 3-mctbyl-bexane.

FIGUR E 6. Disti llati on of the 3-ethyl­pentane concentrate (part D, fig . 1) .

T he ordinate scale on the right gives the re­fracti"e indices of the fract ions of distillate, and t h e ordinate scale on the left gives the boiling point of the d istillate at 725 111111 Hg. The scale of abscissas giyes the " olume of distillate in millili ters. The portion A, enclosed witb ar­rows, 'ivas redistilled.

Journal of Research

w w Z Z« «I-I- Z ZW wa.. a.. ° 3-ETHYLPENTANE 0--' --, 0 0 >- CONCENTRATE >-':3

wo >-58 Z--'I

«>-1-xIw wl-::!, 3~15 w >--0

G ION Z t-,.n:n «

I I-W o c:: Z ::!' :E .~ e w ::!'

o 0_ a.. r<) _~_ .. --'

L() >-N I r-- 57 l-

X w l-

X ,;., « a.. E!:!

~ I 0

~ BP w 0: :> 56 I-« 0: w a.. ::!' W I-

55 X

1-" BEST L OT "-1 X

o BP 725 - BINARY AZEOTROPE

X ncf5 - OF PURE COMPOUNDS

VOLUME IN ML

(, '" Z --' :; w o

Z>- 0 « 0 en I-...J w ' o.. >- zO:-wI «W I~ xI 1WwS? C::!'II

X

1.42

o C

c5 1.41 ~

N

I­« x w o ~

w 2: I-

1.4 0 ~

1.39

0: "­w 0:

FIGUR E 7. Distillation of the 3-ethylpentane concentrate (part A, fig . 6).

Tbe-ord in ate scale OLl tbe right gives t he refractive indiccs of ihc h yd rocarbon port io ll of th e fractions of azeotropic distillate, a nd t he ord inate scale a ll the left gives the boi li ng point of t he azeotro pic dist illate at 725 mm JIg. The scale of abscissas gives t he volume of t he h yd rocarbon portion of t he disti llate in milli liters. 'rhe port ion labeled best lot was analyzed by spectrographic infrared absorption meas urements, the reslIlts of wh ich a re given in table 2.

Hydrocarbons From Petroleum 877106--50--6

417