Methyl cyclopentenolone

Chemical Properties

Methyl cyclopentenolone occurs in beechwood tar and has a caramel-like (burnt sugar) odor. It has been identified as a flavor component in food. Crystals of the compound usually contain 1 mol of water. Synthetic routes of production are of limited importance in comparison with isolation from beechwood tar. Homologs of cyclotene such as 3-ethyl-2-hydroxy-2-cyclopenten-1-one, C₇H₁₀O₂, Mr 126.16, 2-hydroxy-3,4-dimethyl-2-cyclopenten-1-one, C₇H₁₀O₂, Mr 126.16, and 2-hydroxy-3,5-dimethyl-2-cyclopenten-1-one, C₇H₁₀O₂, Mr 126.16, are also used as flavor ingredients and have similar caramel-like properties.
Cyclotene and its homologs are frequently used in flavor compositions for its caramel note, for example, in beverages and in confectionery.

Chemical Properties

Off-white solid

Occurrence

Reported to be found during the dry distillation of wood and in the corresponding tar oil. It has also been identified in fenugreek (FenaroWs Handbook of Flavor Ingredients, 1975).

Uses

Methyl Cyclopentenolone is a flavoring agent that is a white crys- talline powder. it has a nutty odor suggesting a maple-licorice aroma when diluted. it is soluble in alcohol and propylene glycol, slightly soluble in most fixed oils, and sparingly soluble in water. it is obtained by synthesis. it is also termed 3-methyl-cyclopentane-1,2-dione.

Uses

Methyl cyclopentenolone may be used as an analytical reference standard for the quantification of the analyte in commercial products using different chromatography techniques.

Preparation

By ketonic hydrolysis of the corresponding dicarboxylic ester (Arctander, 1969)

Application

Methyl cyclopentenolone is used sparingly in perfume compositions often in combination with Coumarin or Coumarin derivatives. It is an excellent fortifier for such materials in Lavender fragrances, New Mown Hay, "tabac" type fragrances, spicy bases, etc. It falls naturally into Celery seed oil, Lovage, Fenugreek, Tonka, Liatris, Flouve, etc. It is, however, in flavor compositions that Methyl cyclopentenolone has found its truly extensive application.

Toxicity evaluation

The acute oral LD₅₀ value in guinea-pigs was reported as 1.4 g/kg (Dow Chemical Company, 1953) and that in rats as > 1.85 g/kg, while the acute dermal LD₅₀ value in guinea-pigs exceeded 2 g/kg (Moreno, 1976). Methylcyclopentenolone was lethal to mice and rats at ip doses of 0.5-1 g/kg (Shugaev, 1959), and at a concentration of 7 χ 10^-4 m was toxic to cultured human leucocytes (Withers, 1966).

General Description

Methyl cyclopentenolone is one of the flavor compounds of maple syrup, coffee oil and wood smoke. It is reported to be one the key aroma compounds in Wasanbon sugar, contributing to the maple-like flavor. Methyl cyclopentenolone is also one of the major volatile compound formed during the thermal degradation of glucose.