Process for preparing methylvanillyl ketone from isoeugenol

DETAILED DESCRIPTION OF THE INVENTION The present invention concerns a new, alternate process for the production of methylvanillyl ketone (MVK).
The process can be represented as follows.
##STR1## wherein R is hydrogen, C.
sub.
1-5 alkyl especially methyl, ethyl, propyl, butyl or amyl, trifluoromethyl or trichloromethyl; and the oxidation reagent is peroxide such as hydrogen peroxide or disuccinoyl peroxide, peracid such as performic acid, peracetic acid, peroxytrifluoroacetic acid, monopersuccinic acid, m-chloroperbenzoic acid, p-methoxycarbonylperbenzoic acid, O-sulfoperbenzoic acid or monoperphthalic acid, or other oxidation reagents such as iodine-silver oxide, iodine-mercuric oxide, N-bromosuccinimide-perchloric acid, or thallium triacetate.
The oxidation is usually conducted in an aqueous solution of an organic acid such as formic, acetic, propionic, trichloroacetic, or trifluoro acetic acid.
The formic acid and acetic acid generally give better results.
The preferred oxidation reagents are hydrogen peroxide and peracetic acid.
The most preferred embodiment is the combination of hydrogen peroxide and formic acid.
The oxidation generally requires mild heating at about 25.
degree.
C.
-100.
degree.
C.
, preferably at 30.
degree.
C.
-60.
degree.
C.
, for about 1-6 hours or until the reaction is substantially complete.
If hydrogen peroxide and formic acid are used at 35.
degree.
C.
-40.
degree.
C.
, the reaction is substantially complete in about 2.
5 hours or less.
The in situ conversion of the resulting glycol monoester without isolation to MVK is accomplished by heating the reaction mixture together with an aqueous solution of a strong acid and an inert solvent such as benzene, toluene or xylene.
The strong acid used is usually sulfuric, alkyl or aryl sulfonic, hydrobromic, hydrochloric or phosphoric acid.
Preferably, a sufficient amount of 10%-20% aqueous sulfuric acid and toluene is added to the reaction mixture and the entire mixture is heated to reflux until the reaction is substantially completed