Carboxylic acid fluorides benzoyl fluoride

Sulfonyl fluorides are readily obtained from sulfonyl chlorides and KF or KHF2j even in an aqueous medium.801"804 Carboxylic acid fluorides are formed when the acid chlorides are heated with dry KF and can be removed continuously from the reaction mixture by distillation through a column formyl and acetyl fluorides are thus obtained when the acid is heated with benzoyl chloride and KF.805,806 Xylene or acetamide may be used as diluent. Further, a>chloro and at-bromo fatty esters, nitriles, and amides react with KF at temperatures around 100-150°. 

Carboxylic acid fluorides are not of particular preparative importance since the reactions that can be carried out with them proceed analogously with the cheaper carboxylic acid chlorides. These fluorides are very stable, even towards hydrolysis. Formyl fluoride can be kept at room temperature for several hours before it decomposes into CO and HF. The preparation of carboxylic acid fluorides from the corresponding chlorides and KF was mentioned on page 204. If butyric anhydride is heated gradually to 180° with KHF2, butyryl fluoride, b.p. 67° 1167 mm, distils off, and benzoyl fluoride, b.p. 155-156°, can be obtained analogously from benzoic anhydride at 190-240°. KF can also be used in place of KHF2. Yields are around 80-90%.1079... 

SO3 added during 10 min. with occasional cooling at 30-40° under dry Ng to stirred benzoyl chloride, and allowed to stand 1 hr. benzoyl chlorosulfate. Y 99%. F. e., also insertion into carboxylic acid fluorides and esters, s. C. G. Krespan and D. C. England, J. Org. Chem. 40, 2937 (1975). 

Dihalocycloproparenes, in particular the chloro derivatives, are extremely susceptible to hydrolysis and react via ring opening to give carboxylic acid derivatives. Typically, 1,1-dichloro-2,5-diphenylbenzocyclopropene was converted to trimethyl 2,5-diphenylorthobenzoate (12a, 94%) upon reaction with sodium methoxide in benzene and workup in the presence of base. Methanolysis in the absence of base afforded methyl 2,5-diphenylbenzoate. " The same behavior applies to 1,1-dichloro- or l,l-dibromo-2,7-diphenylcyclopropa[()]naphthalene. 1,1-Difluorobenzocyclopropene was hydrolyzed with water to benzoic acid, and the intermediate benzoyl fluoride was isolated and characterized. The hydrolysis of l,l-dihalocyclopropa[6]-naphthalenes afforded naphthalene-2-carboxylic acid, while acid-catalyzed methanolysis of... 

Acylation of alkenes can also be similarly effected with SbFs. Reaction of acetyl fluoride with trifluoroethylene produces 1,1,1,2-tetrafluorohexane-3,5-dione in 40% yield. When antimony pentafluoride is used in excess (more than 6 molar equivalents), 1,1,1,2-tetrafluorobutan-3-one is formed as a side product. Benzoyl fluoride reacts with dilluoroethy lene to form the expected ketone in 39% yield. a, 3-Unsaturated carboxylic acid fluorides have also been used in reactions with perfluoroalkenes. In these cases, a,p-unsaturated ketones are obtained (eq 17). Enol acetates of perfluoroisopropyl methyl ketone and perfluoro-f-butyl methyl ketone react with acetyl fluoride to provide the corresponding p-diketones (eq IS). ... 

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