Thymol, solvent stabilizer

Occurrence In numerous essential oils cymen-2-ol especially in origanum (oregano) oil (Coridothymus capitatus, Lamiaceae) up to 80%, in savory and thyme oil up to 70% cymen-3-ol especially in essential oil of seeds of Orthodon angustifolium (Lamiaceae) up to 72% cymen-8-ol from the frass of the old house borer beetle Hylotrupes bajulus (Cerambycidae). Use Carvacrol as disinfectant and solvent thymol as stabilizer (0.01%) of halothanes and trichloroethene. Mixtures of thymol with methyl IV-methylanthranilate in appropriate ratios have a typical mandarin odor. lit Tetrahedron Lett. 1975, 3585. Helv. Chim. Acta 46, 1480(1963). 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

It has been reported that a crystal of thymol in the stock solution will inhibit bacterial growth [63b] this preservation technique is recommended only when standard solutions are prepared free of acid. Solution stability is a function of nature of analyte and matrix and their concentrations, acid concentration, type of storage container, storage conditions, etc. At extremely low concentrations, contamination from solvents, water and containers must be considered. 

Properties Colorless, volatile liquid sweetish odor. D 1.872-1.877 (20/4C), bp 50.2C, 20C (243 mm Hg). Light sensitive. May be stabilized with 0.01% thymol. Slightly soluble in water miscible with many organic solvents. 

Non-flammable, highly volatile liquid. Characteristic, sweetish, not unpleasant odor, dj 1.871. bp 50.2 bp 20 . nj, 1.3697. Sensitive to tight, may ba stabilized with ST0l% thymol. Soly in water 0.345%. Miscible with petr ether, other Fat solvents. 

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