2-Acetonaphthone

Chemical properties

2-Acetonaphthone smells similar to orange blossomand is a colorless crystalline solid (mp 56 °C). It is usually prepared by Friedel–Crafts acetylation of naphthalene (with acetyl chloride, acetic anhydride, etc.) in the presence of aluminumchloride. In polar solvents (e.g., nitrobenzene), the percentage of the simultaneously formed ??-isomer is lower. Methyl 2-naphthyl ketone is used in eau de cologne, soap perfumes, and detergents. It is a good fixative.

Physical properties

Methyl β-napthyl ketone has a floral, neroli odor suggestive of orange blossom and a strawberry-like flavor.

The Uses of 2-Acetonaphthone

2-Acetonaphthone is a flavoring agent that is a crystalline solid (white or nearly white) with orange blossom-like odor. It is soluble in most fixed oils, slightly soluble in mineral oil and propylene glycol, and insoluble in glycerin. It is obtained by chemical synthesis.

The Uses of 2-Acetonaphthone

2-Acetonaphthone was used in direct time-resolved studies on singlet molecular oxygen phosphorescence in heterogeneous silica gel/cyclohexane systems.

Definition

ChEBI: 2-acetylnaphthalene is a naphthyl ketone that is naphthalene substituted at position 2 by an acetyl group.

Preparation

2-Acetonaphthone may be prepared by Friedel-Crafts reaction of naphthalene, acetyl chloride and AlCl3.

Synthesis Reference(s)

Journal of the American Chemical Society, 99, p. 3101, 1977 DOI: 10.1021/ja00451a041
The Journal of Organic Chemistry, 55, p. 319, 1990 DOI: 10.1021/jo00288a054
Tetrahedron Letters, 19, p. 147, 1978 DOI: 10.1016/S0040-4039(01)85068-1

General Description

2-Acetonaphthone undergoes efficient photoreduction in the presence of tri-n-butylstannane as hydrogen donor. It is solubilized in air-saturated sodium dodecyl sulphate micelles in D₂O or H₂O by pulsed nitrogen laser photolysis for triplet sensitized production of singlet oxygen.

Flammability and Explosibility

Not classified

Biochem/physiol Actions

Odor at 1.0%

Safety Profile

Moderately toxic by ingestion. A human skin irritant. Flammable liquid. When heated to decomposition it emits acrid smoke and fumes

Purification Methods

Separate it from the 1-isomer by fractional crystallisation of the picrate in EtOH (see entry for the 1-isomer above) to m 82o. Decomposition of the picrate with dilute NaOH and extraction with Et2O, then evaporation, give purer 2-acetylnaphthalene. If this residue solidifies, it can be recrystallised from pet ether, EtOH or acetic acid; otherwise it should be distilled in a vacuum and the solid distillate is recrystallised [Gorman & Rodgers J Am Chem Soc 108 5074 1986, Levanon et al. J Phys Chem 91 14 1987]. Purity should be checked by high field NMR spectroscopy. Its oxime has m 145o(dec), and the semicarbazone has m 235o. [Stobbe & Lenzer Justus Liebigs Ann Chem 380 95 1911, Raffauf J Am Chem Soc 72 753 1950, Hunsberger J Am Chem Soc 72 5626 1950, Immediata & Day J Org Chem 5 512 1940, Beilstein 7 IV 1294.]