Halides conversion

The heat profile shows that the reaction has zero order kinetics at first, and then switches to positive order kinetics. The benzophenone hydrazone reacts first only when it is completely consumed, the reaction involving hexylamine begins. Samples were taken and analyzed by and NMR. One sample was taken when the aryl halide conversion was low, at about 5%, and the profile was overall zero order the second when the profile had switched to positive order and the conversion of the halide was greater than 50%. 

Carboxylic acids can be converted to acyl chlorides and bromides by a combination of triphenylphosphine and a halogen source. Triphenylphosphine and carbon tetrachloride convert acids to the corresponding acyl chloride.100 Similarly, carboxylic acids react with the triphenyl phosphine-bromine adduct to give acyl bromides.101 Triphenviphosphine-iV-hromosuccinimide also generates acyl bromide in situ.102 All these reactions involve acyloxyphosphonium ions and are mechanistically analogous to the alcohol-to-halide conversions that are discussed in Section 3.1.2. 

Scheme 3.1 gives some examples of the various alcohol-to-halide conversions that have been discussed. 

Haloalkyl pyrimidines can also be prepared from hydroxyalkyl derivatives by use of the standard reagents for the alcohol-to-halide conversion <1994HC(52)1, 1996CHEC-II(6)93>. 

Allylic alcohols may also be formed from their corresponding halides by reaction with either peracids222 or potassium superoxide and a crown ether223. This latter methodology has been used in the synthesis of a polyether antibiotic, containing an allylic alcohol and a spiroacetal, where other methods have failed223. During allylic halide conversion, allylic... 

Aromatic halides, conversion to aromatic thiols 182-185 by reaction with thiourea 189-191 Aromatic thiols—see also Thiophenols mass spectra 330 preparation of 167-169 from aldehydes and ketones 251-256... 

Sulphenyl cations 793 Sulphenyl halides, conversion to sulphenamides 750 for determination of SH group 291 hydrolysis of 792... 

Phosphonium salt 123 is formed by the reaction of triphenylphosphine with an alkyl halide. Conversion of 123 to the corresponding ylid by reaction... 

The Suzuki coupling of 4-bromo-acetophenone with phenylboronic acid was achieved using Nil2(tmiy)2 with 19 to 58% aryl halide conversion and TONs of 630 to 1930. Amination of aryl chlorides was accomplished by using a nickel hydroimidazoline carbene complex (Equation (27)). ... 

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