Cyclopropane show haloform test or not.. If show then why?
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Answers
hey gullu!
such a nice name..!
your answer is here!
The haloform reaction is a chemical reaction where a haloform (CHX3, where X is a halogen) is produced by the exhaustive halogenation of methyl aldehyde (acetaldehyde) or a methyl ketone (RCOCH3, where R can be either a hydrogen atom, an alkyl or an aryl group), in the presence of a base. The reaction can be used to transform acetyl groups into carboxyl groups or to produce chloroform (CHCl3), bromoform (CHBr3), or iodoform (CHI3).
Haloform reaction scheme:_))
Mechanism is here buddy!
In the first step, the halogen disproportionates in the presence of hydroxide to give the halide and hypohalite (example with bromine, but reaction is the same in case of chlorine and iodine; one should only substitute Br for Cl or I):
{\displaystyle {\mbox{Br}}_{2}+2{\mbox{OH}}^{{}-{}}~\rightarrow ~{\mbox{Br}}^{{}-{}}+{\mbox{BrO}}^{{}-{}}+{\mbox{H}}_{2}{\mbox{O}}} {\displaystyle {\mbox{Br}}_{2}+2{\mbox{OH}}^{{}-{}}~\rightarrow ~{\mbox{Br}}^{{}-{}}+{\mbox{BrO}}^{{}-{}}+{\mbox{H}}_{2}{\mbox{O}}}
If a secondary alcohol is present, it is oxidized to a ketone by the hypohalite:
Bromoform 1.svg
If a methyl ketone is present, it reacts with the hypohalite in a three-step process:
1. Under basic conditions, the ketone undergoes keto-enol tautomerization. The enolate undergoes electrophilic attack by the hypohalite (containing a halogen with a formal +1 charge).
hope this would help you !
This test is shown by compound having double bond only.
But cyclopropane is exceptional case... show haloform test bcoz have high angle strain.. cycle get opens when reacted by halogen.