Calone 1951

Identity and chemistry

Calone 1951 (CAS 28940-11-6) is chemically 7-methyl-2H-1,5-benzodioxepin-3(4H)-one. Its preferred IUPAC name is 7-methyl-2,4-dihydro-3H-1,5-benzodioxepin-3-one. The molecular formula is C10H10O3 and the molecular weight is 178.18. Its structure is written CH₃C₆H₃(OCH₂)₂CO. It is a crystalline solid.

Calone is insoluble in water. It can be difficult to balance in a composition.

Discovery and patent

A United States patent for 1,5-benzoxepin- and benzodioxepin-3-ones as flavor and odorant agents was filed on 15 August 1966 for Pfizer by Beereboom, Cameron and Stephens. The patent names 7-methyl-3,4-dihydro-2H-1,5-benzodioxepin-3-one among its preferred compounds, valued for a watermelon-like taste and odor. It describes the odor and taste as reminiscent of melons, and presents the compounds as flavor agents for foods and odorant agents for perfumes. Blended at about 0.0001 to 1.0 weight percent with ingredients such as orris oil concrete, violet oil concrete and sandalwood oil, these ketones give a distinct leafy or fresh effect, most evident in violet leaf perfumes.

Production

Calone is made from 4-methylcatechol. One route reacts it with methyl bromoacetate in a Williamson reaction, a Dieckmann condensation and a hydrolysis-decarboxylation, with a yield of up to 57%. Potassium iodide used as a catalyst in the first step raises the yield of the intermediate 4-methylcatechol dimethylacetate to 95% and the overall yield of the ketone to 68%. A route from 4-methylcatechol and 1,3-dichloroacetone ends with recrystallization from a mixture of acetone and hexane and gives a white crystalline solid with a yield of up to 80%.

Analogues

In 2014, the synthesis and fragrance properties of several related aliphatic analogues were reported. The isopropyl homologue was later released by a fragrance house under the brand name Cascalone, a sweet, watery version of calone with a transparent floral signature.

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