R E S E A R C H

FC Ν Chemistry Opens New Fields Researchers look at fluorocarbon nitrogen chemis­try for clues to high strength and chemical resistance

member of the series, ( C F 3 ) S N is diffi­cult to make by electrolysis, but Minne­sota Mining and Manufacturing makes the inert perfluoro tribiatyl compound— (CaF^sN—commercially by this elec­trochemical process.

Both secondary amines and second­ary nitrides must be made indirectly. Carbamyl chlorides and HF in an elec­trochemical process substitute fluorine atoms for hydrogen and chlorine atoms. Heating drives out COF2; further reac­tion with HF or fluorine produces either the fluorocarbon amine or nitride:

HILE hydrocarbons most often de­compose by breaking carbon-hydrogen bonds, fluorocarbons apparendy de­compose by breaking carbon-carbon, not carbon-fluorine, bonds. The strength of the C—F bond is believed to be a major cause of the good chemi­cal and thermal resistance of fluorocar­bons. Might still more interesting com­pounds result with still stronger bonds? Seeling a possible answer, researchers are now studying the «carbon-nitrogen bonds in fluorocarbon nitrogen com­pounds.

An indication of the possibilities of such compounds is CF3N=MCF3, which is untouched by elemental fluorine up to 500° C. Its resistance to further re­action with fluorine is vastly better than that of C—Ν and Ν—Μ bonds in organic molecules.

What of the other possibilities? Comparatively little is; known of the preparation and reactions o f even the simplest possible compounds containing fluorine and nitrogen-euorocarbon amines. John A. Young or the Univer­sity of Florida says that systematic fluorocarbon nitrogen chemistry is still in its toddling stages. Present knowl­edge shows anything from complete correlation to complete discrepancy with classical organic nitrogen chemis­try. Developing a systematic chemis­try of fluorocarbon nitrogen, derivatives would serve to open a whole field of new synthetic materials, says Young, and it will add to our understanding of organic nitrogen reaction mechanism.

Two series of fluorocarbon com­pounds are possible-emther fluorine re­placing hydrogen in the alkyl groups only or throughout the molecule. Be­cause two kinds of hydrogen exist in primary and secondary amines (amine hydrogen and alkyl hydrogen), am­biguities are possible i n connoting these compounds simply .s fluorocarbon amines. For -want of a better name, Young suggests calling the completely substituted compounds ' nitrides."

Organic amines R3N R 2 NH RNH2 NH 3

Fluorocarbon amines (RF) 3 N (RF)2NHE RFNH2 NH S

"Nitrides" (RF) 3 N (RF) 2 NF RFNF2 N F 3

(RF refers to alkyl group with hydro­gen atoms replaced by fluorine.)

• Via Electrochemistry, Classic organic amine preparation involves either reducing a more oxidized nitro­gen compound or nitrogen atom alkyla-tion. Neither of these methods works for fluorocarbon amines or nitrides. Such compounds as fluorocarbon ni-triles (RFCN) are reduceable, but they go to a 1,1-dihydro amine of the type RFCH2NH2 , not a true fluoro­carbon amine, according to Young.

At present, the best way to make fluorocarbon amines and nitrides seems to be by an electrochemical process. Low-voltage current is passed through a solution of a particular organic amine in anhydrous hydrofluoric acid to make the tertiary compounds. The first

(CH3)2NCOCl

600° C.

H F > (CF 3 KNCOF e

C F 3 N = C F 2 + COF2

CF,N=CFo

CF.N=CF.>

HF 150°

F>

( C F 3 ) 2 N H

( C F 3 ) 2 N F

So far, this procedure works best for methyl derivatives; longer chain car­bamyl chlorides form heterocyclic rings whose structure is difficult to elucidate.

Considerable doubt exists, r~ys Young, that primary fluorocarbon amines will ever be reported because of probable instability which would prevent isolation. He bases his con­clusion on secondary amines which readily lose HF with slightest traces of water. Primary fluorocarbon nitrides such as CF3NF2 can be made, along

Research at National Cash Register National Cash Register's $5 million engineering research center, to b e completed in June, will provide greatly expanded facilities for all phases of business machine development. Included in the center's activities will be research on new types of solid-state electronic devices, new magnetic materials, ferroelectric materials, high­speed printing principles, and electroluminescent phenomena. Also, fundamental research will be conducted in electrochemistry, colloid, and physical chemistry, along with work in application of radioisotopes to new products and processes.

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RESEARCH

with perfluoro azomethane and per-fluoro hydrazine derivatives, by direct fluorination of methylaniines; however, the reaction is difficult to control and yields are poor. To date no convenient or systematic preparation has been de­veloped for the series of primary fluoro-carbon nitrogen compounds.

• Fluorocarbon Amides· Simple amides of fluorocarbon acids are very easily made, even more easily than amides of organic acids. Researchers first thought that primary fluorocarbon amines might be obtained from pri­mary fluorocarbon amides in much the same way organic amines are obtained from organic amides—using the Hof-mann degradation reaction. Extensive investigation showed Hofmann degra­dation reaction products from fluorocar­bon amides to be halides, hydrides* isocyanates or coupled fluorocarbon groups, rather than amines. The actual product depends on fluorocarbon amide's chain length and the hypo-halite used:

Organic amide: RCONH2 + NaOX > R N H 2

Fluorocarbon amide: CF3CONH0 + NaOX > CFfcCF3

CF 3 (CF 2 ) 2 CONH 2 + NaOBr > CF3CF2CF2Br

CF3(CF2)2CONHU 4- NaOI — • CF3CF2CF2rI

True "perfluo" amides, containing no hydrogen, have been unknown until recently when perfluoro-N,A7-dimethyl acetamide was isolated from electro­chemical products of the analog .Ν,ΛΤ"-dimethyl acetamide. The chemistry remains as yet unknown for these per­fluoro amides. Young points out that dimethyl acetamide, with a molecular weight of 87, boils at 166° C ; and the perfluoro compound, molecular weight 249—almost three times as much—boils 130° lower.

Fluorocarbon nitrogen chemistry has developed to its present state largely i n the last five years, as compared to or­ganic nitrogen chemistry which, has been developing over 100 years. Pre­dictions are risky, Young admits, but it would be surprising if some valuable practical application were not found in the next five years.

• G. D. Searle has installed a radio­active tracer lab. It will concentrate on study of radioactive compounds in relation to disease development.

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