4'-Methylacetophenone

Description

4'-Methylacetophenone has a fruity, floral odor resembling acetophenone and a sweet, strawberry-like flavor. May be prepared by slow addition of acetyl chloride to a mixture of toluene and AlCl in an ice bath and under vacuum, maintaining the temperature at +5°C and then letting it increase to +20°C.

Chemical properties

4'-Methylacetophenone has been identified in Brazilian rosewood oil and in pepper. It occurs as colorless crystals with a floral, sweet odor that is milder than that of acetophenone. 4-Methylacetophenone is prepared from toluene and acetic anhydride or acetyl chloride by a Friedel–Crafts reaction. It is used for blossom notes in mimosaand hawthorn-type perfumes, especially soap perfumes.

Occurrence

Reported found in the essential oil distilled from the wood of Myrocarpus fastigiatus, Myrocarpus frondo sus, Bois de Rose. Also reported found in sour cherry, orange and grapefruit peel oil, black currants, guava, peach, blackberry, celery, potato, tomato, mentha oils, pepper, parsley, smoked fish, cognac, parmesan cheese, cocoa, tea, soybean, cloudberry, mango, cauliflower, broccoli, rice bran, buckwheat, dried bonito, cherimoya, calabash nutmeg and mastic gum leaf oil, cooked cabbage, mandarin juice.

The Uses of 4'-Methylacetophenone

4'-Methylacetophenone is a methylated acteophenone used in cosmetics and perfumery. The presence of 4'-Methylacetophenone has been shown to accelerate the photopolymerization of Methyl methacrylate.

The Uses of 4'-Methylacetophenone

4'-Methylacetophenone is used as a flavoring agent. It reacts with morpholine to get 4-(p-tolyl-thioacetyl)-morpholine in the presence of sulfur as a reagent. Further, it is used as an intermediate in the manufacture of active pharmaceutical ingredients, perfumes and cosmetics.

Preparation

By slow addition of acetyl chloride to a mixture of toluene and AlCl in an ice bath and under vacuum, maintaining the temperature at +5°C and then letting it increase to +20°C.

Definition

ChEBI: 4'-Methylacetophenone is an aromatic ketone. It is a metabolite found in or produced by Saccharomyces cerevisiae.

Taste threshold values

Taste characteristics at 20 ppm: sweet, creamy, fruity, cherry and heliotropine-like.

Synthesis Reference(s)

Journal of the American Chemical Society, 110, p. 2560, 1988 DOI: 10.1021/ja00216a032
Tetrahedron Letters, 27, p. 2965, 1986 DOI: 10.1016/S0040-4039(00)84691-2

General Description

4′-Methylacetophenone is a clear colourless to pale yellowish liquid that occurs naturally in mango, tomato and orange.

Safety Profile

Moderately toxic by ingestion. A human skin irritant. A flammable liquid. When heated to decomposition it emits acrid smoke and irritating fumes. See also KETONES.

Purification Methods

Impurities, including the o-and m-isomers, are removed by forming the semicarbazone (m 212-213.5o) which, after repeated crystallisation, is hydrolysed to the ketone. [Brown & Marino J Am Chem Soc 84 1236 1962.] It can also be purified by distillation under reduced pressure, followed by low temperature crystallisation from isopentane. [Beilstein 7 IV 701.]