2-метилнафталин

Описание

2-Methylnaphthalene is a polycyclic aromatic hydrocarbon (PAH), consisting of two-fused aromatic rings with a methyl group attached on one of the rings at the number two carbon.
2-Methylnaphthalene is a natural component of crude oil and coal, and is found in pyrolysis and combustion products such as cigarette and wood smoke, emissions from combustion engines, asphalt, coal tar residues, and used oils (ATSDR, 1995; HSDB, 2002; Warshawsky, 2001).
In the United States, 2-methylnaphthalene is used for making detergents, dyes, solvents, as well as vitamin K. 2-methylnapthalene is also used to make some pesticides, or as an additional ingredient in some pesticides. 2- methylnaphthalene is released into the environment when wood or fossil fuels are burned or when there are spills of products containing fossil fuels. 2-methylnaphthalene can evaporate or break down quickly in soils exposed to air or containing certain microorganisms, but it could stay a year or more under other conditions in certain sediments or soils.

Химические свойства

1-Methylnaphthalene and 2-methylnaphthalene are naphthalenerelated compounds. 1-Methylnaphthalene is a clear liquid and 2- methylnaphthalene is a solid. Insoluble inwater; soluble in alcohol and ether. Combustible. both can be smelled in air and in water at very low concentrations. The taste and odor of 2-methylnaphthalene have not been described. Its presence can be detected at a concentration of 10 ppb in air and 10 ppb in water.

Использование

2-methylnaphthalene are used to make other chemicals such as dyes, insecticides, Organic synthesis and resins. Pure 2-methylnaphthalene is a component used in the manufacture of vitamin K and the insecticide carbaryl (1-naphthyl-N-methylcarbamate) (HSDB, 2002).
Methylnaphthalene (CASRN 1321-94-4) refers to a mixture of approximately two-thirds 2-methylnaphthalene and one-third 1-methylnaphthalene (CASRN 90-12-0). Methylnaphthalene is manufactured from coal tar through the extraction of heteroaromatics and phenols. Distillation of methylnaphthalene removes 1-methylnaphthalene, leaving 2-methylnaphthalene. Mixtures containing 2-methylnaphthalene are used in the formulation of alkyl-naphthalenesulfonates (used for detergents and textile wetting agents), chlorinated naphthalenes, and hydronaphthalenes (used as solvents).

Методы производства

Alkylnaphthalenes are formed as pyrolysis products in cigarette smoke. Some have been identified in commercial carbon paper. They are also the major components of the C10–C13 alkylnaphthalene concentrate fraction, which distills at 400–500
F. A C11–C12 petroleum mixture of reformates that contained about 23% alkylnaphthalenes caused skin and eye effects. The toxicity of the alkylnaphthalenes to marine species is greater than that of the alkylbenzenes (85). The toxicity and the bioaccumulation increase with molecular weight. Nocardia cultures, isolated from soil, preferentially oxidized alkylnaphthalenes when methylated in the two positions. Methylnaphthalene can occur as the 1- or 2-, the alpha or the beta isomer. 1-Naphthalene, a flammable solid, has also been identified in the wastewater of coking operations, and in textile processing plants. Methylnaphthalene is used as a component in slow-release insecticides and in mole repellents. Workplace exposures to 18–32 mg/m3 for 2-methylnaphthalene have been reported.

Определение

ChEBI: A methylnaphthalene carrying a methyl substituent at position 2.

Общее описание

White crystalline solid.

Реакции воздуха и воды

Insoluble in water.

Профиль реактивности

2-Methylnaphthalene is incompatible with strong oxidizing agents. 2-Methylnaphthalene is also incompatible with peroxides and oxygen.

Опасность

Lower respiratory tract irritant and lungdamage. Questionable carcinogen.

Пожароопасность

2-Methylnaphthalene is combustible.

Канцерогенность

The carcinogenic potential of 1- and 2-methyl was investigated in B6C3F1 mice. Female and male mice were given methylnaphthalene in their diets for 81 weeks. The results indicated that 1-methyl was a possible weak carcinogen in the lung of male but not female mice whereas 2-methyl did not possess unequivocal carcinogenic potential in these mice.

Экологическая судьба

Biological. 2-Naphthoic acid was reported as the biooxidation product of 2-methylnaphthalene by Nocardia sp. in soil using n-hexadecane as the substrate (Keck et al., 1989). Dutta et al. (1998) investigated the degradation of 2-methylnaphthalene using a bacterial strain of Sphingomonas paucimobilis grown on phenanthrene. Degradation products identified using GC-MS were 4- methylsalicylate, 2-methylnaphthoate, and 1-hydroxy-2-methylnaphthoate.
Estimated half-lives of 2-methylnaphthalene (0.6 μg/L) from an experimental marine mesocosm during the spring (8–16 °C), summer (20–22 °C), and winter (3–7 °C) were 11, 1.0, and 13 d, respectively (Wakeham et al., 1983).
Photolytic. Fukuda et al. (1988) studied the photodegradation of 2-methylnaphthalene and other alkylated naphthalenes in distilled water and artificial seawater using a high-pressure mercury lamp. Based upon an experimentally rate constant of 0.042/h, the photolytic half-life of 2- methylnaphthalene in water is 16.4 h.
Phousongphouang and Arey (2002) investigated gas-phase reaction of naphthalene with OH radicals in a 7-L Teflon chamber at 25 °C and 740 mmHg containing 5% humidity. The rate constant for this reaction was 4.86 x 10^-11 cm³/molecule?sec.
Chemical/Physical. An aqueous solution containing chlorine dioxide in the dark for 3.5 d at room temperature oxidized 2-methylnaphthalene into the following: 1-chloro-2-methylnaphthalene, 3-chloro-2-methylnaphthalene, 1,3-dichloro-2-methylnaphthalene, 3-hydroxymethylnaphthalene, 2-naphthaldehyde, 2-naphthoic acid, and 2-methyl-1,4-naphthoquinone (Taymaz et al., 1979).

Методы очистки

Fractionally crystallise repeatedly from its melt, then fractionally distil under reduced pressure. It has been crystallised from *benzene and dried under vacuum in an Abderhalden pistol. It can be purified via its picrate (m 114-115o) or better via the 1,3,5-trinitrobenzene complex as for 1-methylnaphthalene (above). [Beilstein 5 IV 1693.]