Acetic acid homoconjugation

CH2CICOOH is somewhat stronger than acetic acid but remains within the family of w ak acids. Its pK in acetic add must close to 12.5 and in 1,2-dichloroethane it cxild around 17. Chloroacetic acid is appreciably dimerised in non polar solvents ) and its tendency towards homoconjugation with its anion is very pronounced ) (pKhbj = —2.94 in acetonitrile). 

The strength of sulphuric acid is usually considered as intermediate between those of HCl and HBr. Thus, the following pK values have been determined or interpolated 7.0 in acetic acid , 7.25 in acetonitrile and about 9.5 in 1,2-dichloroethane. This acid exists essentially as monomer in non-aqueous solvents, but has a strong affinity for its anion as shown in homoconjugation studies in nitromethane acetonitrile (pKhbJ —3 ) and in propylene carbonate ... 

The strength of this acid lies between those of sulphuric acid and hydrogen chloride. pK values of 8.6,8.4 and 6.0 have been obtained in acetic acid, acetonitrile and nitromethane, respectively By interpolation, a pK of about 10 can be assumed in l,2-dichloroethane No evidence of dimerisatim has been reported in these solvents. Like all acids considered before, methanesulphonic add readily homoconjugates with its anion, pKhbj = —3.5 in acetorutrile ... 

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