Patent GB-583264-A (GB)
Title: Production of n-substituted fluoroacetamides
Filed: 1944-04-24
Abstract: N-substituted fluoroacetamides are prepared by heating a fluoroethylene of the formula CF2=CFX, where X is hydrogen or a halogen, with an aliphatic or aromatic primary or secondary amine at between room temperature and 250 DEG  C. and at a pressure up to 350 atmospheres and simultaneously or subsequently treating the reaction mixture with water.  Advantageously, the reaction is carried out in the presence of a base which serves to remove hydrogen halides formed in the reaction, but may also function as a basic catalyst.  The products have the general formula CHFX.CONRR1, where X is hydrogen or halogen and -NRR1 is the residue of the primary or secondary amine used; the products are stated to be novel when R is an alkyl, aralkyl or alkaryl group and R1 is hydrogen or an alkyl, aryl, alkaryl, or aralkyl group.  Where a fluoroethylene is used having the above formula in which X is hydrogen or a halogen other than fluorine, two products may be formed which may be represented as CHFX.CONRR1 and CHF2.CONRR1, but with tetrafluoroethylene a single product only is formed.  Desirably, the reaction should be carried out in the presence of a small amount of water, thus, sufficient may be present as impurity in the reactants or as water of crystallization in the basic catalyst employed.  If no water is present during the reaction, the products are washed with an aqueous alkaline solution.  The reaction is preferably effected at between 50 DEG  to 200 DEG  C. and at subatmospheric, atmospheric or superatmospheric pressure, but desirably at 1 to 250 atmospheres.  The process is usually carried out in a high-pressure reaction vessel, but may also be carried out in the vapour phase by passing the vaporized reactants through a heated tube.  Normally, there is used a molal excess of amine over the fluoroethylene with a molal ratio of water to fluoroethylene of 0.1 to 2 and, if desired, in the presence of an organic solvent.  In examples: (1) n-butylamine in diethyl ether is heated with tetrafluoroethylene in an autoclave using borax as catalyst and N-n-butyl difluoroacetamide is recovered by ethereal extraction and rectification; (2) di-n-butylamine and tetrafluoroethylene are reacted similarly to yield N-di-n-butyl difluoroacetamide and (3) mono-methyl aniline and tetrafluoroethylene to yield N-methyl difluoroacetanilide; (4) n-butylamine is reacted with chloro-trifluoroethylene by the method of (1) above, the mixture being filtered free of solid and fractionated to separate the products, namely, N-n-butyl difluoroacetamide and N-n-butyl chlorofluoroacetamide; (5) hexamethylene diamine and tetrafluoroethylene are reacted as in (1) above, yielding the difluoroacetamide of hexamethylene diamine; (6) n-octylamine and tetrafluoroethylene are heated together in an autoclave and yield N-n-octyl difluoroacetamide. The following amines are typical of many specified as other suitable starting materials: methyl, dimethyl, methyl ethyl, octadecyl, cyclohexyl, allyl and methallyl amines, ethylene diamine, tetramethylene diamine, decamethylene diamine and their mono-N-alkylated derivatives, N : N1-dimethyl hexamethylene diamine, toluidines, N-methyl toluidine, amino acids and amino esters.  Other fluoroethylenes mentioned are trifluoroethylene and bromotrifluoroethylene.  Further examples of basic catalysts include disodium phosphate, sodium and potassium carbonates, bicarbonates, acetates, cyanides and hydroxides, various organic bases such as a tertiary amine and an excess of the particular amine employed in the reaction.  The products may be used in pharmaceuticals, plasticisers and bactericides (see Group VI). The amides may be hydrolysed to the corresponding fluoroacetic acids.ALSO:N-substituted fluoroacetamides of the general formula CHFX.CONRR1 where X is hydrogen or halogen and -NRR1 is the residue of a primary or secondary aliphatic or aromatic amine may be employed as bactericides.  Compounds specified are N-n-butyl difluoroacetamide, N-di-n-butyl difluoroacetamide, N-methyl difluoroacetanilide, N-n-butyl difluoroacetamide, N-n-butyl chlorofluoroacetamide, the difluoracetamide of hexamethylene diamine and N-n-octyl difluoroacetamide.  These compounds may be prepared from fluoroethylenes of the formula CF2=CFX and primary and secondary aliphatic and aromatic amines (see Group IV) and there may be mentioned as typical of many specified starting materials, from which fluoracetamides of the above formula may be derived, methyl, dimethyl methyl ethyl, octadecyl, cyclohexyl, allyl and methallyl amines, ethylene diamine, tetramethylene diamine and their N-alkylated derivatives, N:N1-dimethyl hexamethylene diamine, toluidines, N-methyl toluidine, amino acids and amino esters; the fluoroethylenes specified are trifluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene and tetrafluoroethylene.