Distinguishing Tests

My book says that we can distinguish between 2 hydroxy butanoic acid (A) and 3 hydroxy butanoic acid (B) by haloform tests. It says that B gives positive haloform test. I am fine with it.
I don't get why A doesnot give positive test as it is also a sec. alcohol .

2 Answers

1
Euclid ·

but i dont get how B shows the test!!!!

A should give....

y do u think it yes for B???

39
Pritish Chakraborty ·

For A, in the basic medium, -COOH loses a proton to become -COO-, which gives a +I effect. This weakens the acidity of the proton which is on the carbon alpha to -OH. Hence the proton is not taken and the alpha-halogenation does not take place as planned. So no haloform test.
On the other hand, B will not be affected by carboxylate anion's inductive effect as such, as the -OH group is further from it. Inductive effects weaken with distance.

Your Answer

Close [X]