Organic Lab Reactions 63

Organic Lab Reactions 63 - AND HYDROGEN FLUORIDE...

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58 ALIPHATIC FLUORINE COMPOUNDS product by reaction with mercuric fluoride, 21 and 1,1,2,2-tetrafluoro- ethane is prepared from acetylene tetrabromide by way of the difluoro- dibromide, CHBr 2 CHF 2 , through the same sequence of treatments. 36 Several procedures have been devised to circumvent the necessity of synthesizing mercuric fluoride. The nascent salt, prepared by passing hydrogen fluoride into a mixture of mercuric oxide and the organic reagent, may be employed. 41 The oxide is instantly converted to the fluoride, which reacts at once with the organic halide. The reaction is strongly exothermic, and adequate mechanical means of dissipating the heat must be provided in orfler to keep the reaction under control. The mercury halide produced can be recovered and used for the prepara- tion of mercuric oxide for another run. Examples of preparations effected by this method are given in Table II. TABLE II PREPARATION OF ALIPHATIC FLUORIDES BY THE USE OF MERCURIC OXIDE
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Unformatted text preview: AND HYDROGEN FLUORIDE " Starting Material CHBr 2 CHBr 2 CH 2 BrCHBr 2 CH 3 COCH 2 CH 2 Br CH 2 C1 2 CHCU CH 3 CHC1 2 CH 3 (CH 2 ) 6 CHC1 2 (C6H 6 ) 2 CC1 2 (CfrEWsCCl CHC1 2 CC1F 2 CHF 2 CC1 3 Products CHBr 2 CHBrF CHBr 2 CHF 2 CH 2 BrCHBrF CH2BrCHF2 CH 3 COCH 2 CH 2 F CH2F2 * CHC1F 2 CH 3 CHF 2 CH 3 (CH 2 ) 6 CHF 2 (C 6 H 6 ) 2 CF 2 (C 6 H 6 ) 3 CF CHF 2 CC1F 2 CHF 2 CC1F 2 Yield 80% 80% 80% 80% 60-70% 70-80% 70-80% 70% 80% 75% 40-60% . Another procedure consists in adding a halogen to mercurous fluo-ride in order to generate a mercuric fluorohalide; such a salt acts sub-stantially as a mixture of mercuric fluoride and mercuric halide. 38 Methyl fluoride was prepared in yields of better than 80% by dissolving one equivalent of iodine in a large quantity of methyl iodide and pro-gressively feeding one equivalent of mercurous fluoride into the solu-" Henne, J. Am. Chem. Soc., 60, 1569 (1935)-...
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This note was uploaded on 11/20/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.

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