In contrast to the primary and secondary alcohols, tertiary alcohols are relatively stable to
cold chromic acid but under more vigorous conditions (higher temperature; stronger acid) even
tertiary alcohols (like ketones) suffer oxidative cleavage of carbon-carbon bonds. This
relationship has led to the development of a convenient qualitative test for distinguishing primary
and secondary alcohols (and aldehydes) from tertiary alcohols (and ketones). The qualitative test
involves the addition of a solution of CrO3 in sulfuric acid (Jones' Reagent) to a solution of the
compound being tested in acetone. This reagent oxidizes primary and secondary alcohols and all
aldehydes (via its hydrate) with a distinctive color change (orange to green or blue-green) and it
gives no visible reaction with tertiary alcohols and ketones under the conditions of the test.
Primary and secondary alcohols and aliphatic aldehydes give a positive test within a few seconds
while aromatic aldehydes require 30 seconds to one minute. Tertiary alcohols and ketones
produce no visible change in several minutes. [The reagent will slowly oxidize tert-butyl alcohol
and phenol]. This test, in conjunction with those to be described in the next experiment, Tollens,
Purpald, Fehling's, and the Iodoform tests, have proved to be invaluable tools for detecting the
presence of ketones and aldehydes in unknown compounds.
In contrast to the primary and secondary alcohols, tertiary alcohols are relatively stable tocold chromic acid but under more vigorous conditions (higher temperature; stronger acid) eventertiary alcohols (like ketones) suffer oxidative cleavage of carbon-carbon bonds. Thisrelationship has led to the development of a convenient qualitative test for distinguishing primaryand secondary alcohols (and aldehydes) from tertiary alcohols (and ketones). The qualitative testinvolves the addition of a solution of CrO3 in sulfuric acid (Jones' Reagent) to a solution of thecompound being tested in acetone. This reagent oxidizes primary and secondary alcohols and allaldehydes (via its hydrate) with a distinctive color change (orange to green or blue-green) and itgives no visible reaction with tertiary alcohols and ketones under the conditions of the test.Primary and secondary alcohols and aliphatic aldehydes give a positive test within a few secondswhile aromatic aldehydes require 30 seconds to one minute. Tertiary alcohols and ketonesproduce no visible change in several minutes. [The reagent will slowly oxidize tert-butyl alcoholand phenol]. This test, in conjunction with those to be described in the next experiment, Tollens,Purpald, Fehling's, and the Iodoform tests, have proved to be invaluable tools for detecting thepresence of ketones and aldehydes in unknown compounds.
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