2-PHENYLPROPIONALDEHYDE

Chemical properties

clear colorless liquid

Chemical properties

2-PHENYLPROPIONALDEHYDE identified in dried mushroom, is a colorless liquid with a green hyacinth odor. Hydratropaldehyde can be hydrogenated to hydratropic alcohol, which is also used to a limited extent by reaction of p-ethylbenzyl chloride and isobutyric aldehyde in the presence of catalysts. The product is used in perfumes for, for example, household products.

Chemical properties

2-Phenylpropionaldehyde has an intense, green, floral odor reminiscent of hyacinth.

Occurrence

Reported found in microbially fermented tea and some varieties of mushrooms.

The Uses of 2-PHENYLPROPIONALDEHYDE

2-Phenylpropionaldehyde is a precursor in the synthesis of N,N,β-Trimethyl-phenethylamine Hydrochloride (T796625).

Preparation

By alkaline condensation of acetophenone and ethyl chloroacetate; also by distillation of methylphenyl ethylene glycol in 91% yields (under atmospheric pressure).

Definition

ChEBI: 2-phenylpropanal is a member of the class of phenylacetaldehydes that is phenylacetaldehyde in which a hydrogen alpha to the aldehyde carbonyl group has been replaced by a methyl group. The major species at pH 7.3.

Production Methods

The most important synthetic route to 2-phenylpropionaldehyde is the rhodiumcatalyzed hydroformylation of styrene. The catalyst [HCo(CO)4] is unsuitable in this process because it favors the hydrogenation of styrene. The use of chiral rhodium complexes leads to the formation of optically active aldehydes when prochiral olefins, such as styrene, are used. Asymmetric hydroformylation, however, has so far found only small industrial application because of insufficient purity of the enantiomers. Other synthetic methods are the gas-phase oxidation of a-methylstyrene on Cu, Bi–Mo– P–SiO2, or Pd salt catalysts, the rearrangement of epoxidized a-methylstyrene, and the dehydrogenation of 2-phenyl-1-propanol on Ag catalysts at reaction temperatures of ca. 600 ℃.

Synthesis Reference(s)

Journal of the American Chemical Society, 97, p. 5608, 1975 DOI: 10.1021/ja00852a062
Organic Syntheses, Coll. Vol. 3, p. 733, 1955
Tetrahedron Letters, 15, p. 3059, 1974

General Description

2-Phenylpropionaldehyde is used in perfumes for its green hyacinth odor.

Flammability and Explosibility

Non flammable

Trade name

Floralozone (IFF), Florazon (Symrise).

Safety Profile

: Moderately toxic by ingestion. Combustible liquid. When heated to decomposition it emits acrid smoke and irritating fumes. See also ALDEHYDES.

Purification Methods

It may contain up to 15% of acetophenone. Purify it via the bisulfite addition compound [Lodge & Heathcock J Am Chem Soc 109 3353 1987] and see Chapter 2 for preparation and decomposition of bisulfite adducts. [Beilstein 7 IV 695.]