Chlorobutanoic acid, acidity

Because inductive effects operate through cr bonds and are dependent on distance, the effect of halogen substitution decreases as the substituent moves farther from the carboxyl. Thus, 2-chlorobutanoic acid has p/chlorobutanoic acid has p/chlorobutanoic acid has p/C., = 4.52, similar to that of butanoic acid itself. 

Theoretical predictions, based on AMI MO theory, for gas-phase elimination reactions of 3-chloropropanoic and 2-chlorobutanoic acids are consistent with experimental results four-, five-, and six-membered transition states have been discussed. ... 

The distance the electron-withdrawing group is from the carboxylic acid group is also important. For example, butanoic acid has = 1.5 x 10 4-chlorobutanoic acid has K = 3 x 10" 3-chlorobutanioic acid has K = 8.9 x 10 and 2-chlorobutanoic acid has = 1.4 x 10". This shows that the chlorine is more effective the closer it gets to the carboxylic acid group. 

Problem 16.69 Convert 2-chlorobutanoic acid into 3-chlorobutanoic acid. ... 

Chlorobutanoic acid is dehydrohalogenated to 2-butenoic acid and HCl is added. H adds to give a /3-carbocation which bonds to Cl to form the /3-chloroacid. 

SAMPLE SOLUTION (a) The reactant is a primary alcohol and so can be oxidized either to an aldehyde or to a carboxylic acid. Aldehydes are the major products only when the oxidation is carried out in anhydrous media. Carboxylic acids are formed when water is present. The reaction shown produced 4-chlorobutanoic acid in 56% yield. 

Table 3.3 Acidities of Chlorobutanoic Acids as Position of Chlorine Attachment Is Varied...

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