90-12-0

Colorless liquid. Freezing point-22°C (7.6°F). Boiling point 240-243°C (464-469°F). Flash point 82°C (180°F). Denser than water. Derived from coal tar and used in organic synthesis.

1-METHYLNAPHTHALENE(90-12-0) is sensitive to heat. Reacts with strong oxidizing agents. Incompatible with oxygen and peroxides .

Insoluble in water.

Moderate fire risk. Lower respiratory tractirritant and lung damage. Questionable carcinogen.

Harmful if inhaled. Liquid causes irritation of the eyes and skin and skin photosensitization. Harmful if swallowed. Chronic exposure may cause liver or kidney damage.

This chemical is combustible.

1-methylnaphthalene is a methylnaphthalene carrying a methyl substituent at position. It is a polycyclic aromatic hydrocarbon (PAH). It is present in cigarette smoke, wood smoke, tar, asphalt, and at some hazardous waste sites. The main use of 1-methylnaphthalene is as a raw material for naphthoic acid, fluorescent whitening agents, and surfactants. It is also used as a raw material for dyestuff dispersants and heat transfer oils, and as a solvent for agricultural chemical.

1-methylnaphthalene is a methylnaphthalene carrying a methyl substituent at position. Methylnaphthalene appears as bluish-brown oil or a clear yellow liquid. Coal tar or mothball odor. 1-methylnaphthalene is a colorless liquid. Insoluble in water; soluble in alcoholand ether. Denser than water. Combustible. Derived from coal tar and used in organic synthesis. It has a role as a carcinogenic agent and a plant metabolite.

Reported found in apple, grape, peach, strawberry, onion, peas, bell pepper, Gruyere and parmesan cheese, milk, white wine, cocoa, coffee, tea, filberts, peanuts, oats, soybeans, Japanese plum, beans, starfruit, trassi, tamarind, rice, buckwheat, wild rice, endive, nectarine, lamb’s lettuce, okra, crayfish, rooibus tea (Aspalathus linearis), capsicum peppers and milk products. Methylnaphthalene was identified as a volatile component of cassava, roasted filberts and nectarines. Assorted types of lima, pinto, red kidney, black, navy and mung beans, soybeans, split peas and lentils were found to contain 1-methylnaphthalene at concentrations ranging from 2.8 to 49.2 ppb.

1-Methylnaphthalene can be used in:
The synthesis of various polycyclic aromatic hydrocarbons (PAHs), including naphtho[a]carbazoles and naphthopyrones.
The preparation of 1-methylnaphthalene based tocainide analog as skeletal muscle voltage-gated sodium channel blocker.
The synthesis of aminobenzoyl-2-hydroxy-1-naphthyl hydrazine, a potential HIV reverse-transcriptase-DNA-polymerase inhibitor (RTI).

ChEBI: 1-methylnaphthalene(90-12-0) is a methylnaphthalene carrying a methyl substituent at position 1. It has a role as a carcinogenic agent and a plant metabolite.

Generally obtained from coal tar and petroleum oils.

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.

Detection: 7.5 to 20 ppb.

Taste characteristics at 1 ppm: naphthyl-like with a medicinal nuance.

Journal of the American Chemical Society, 65, p. 295, 1943 DOI: 10.1021/ja01242a503
The Journal of Organic Chemistry, 53, p. 4466, 1988 DOI: 10.1021/jo00254a009
Tetrahedron Letters, 29, p. 97, 1988 DOI: 10.1016/0040-4039(88)80026-1

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.

Dry 1-methylnaphthalene for several days with CaCl2 or by prolonged refluxing with BaO. Fractionally distil it through a glass helices-packed column from sodium. Purify it further by solution in MeOH and precipitation of its picrate complex by adding to a saturated solution of picric acid in MeOH. The picrate, after crystallisation to constant melting point (m 140-141o) from MeOH, is dissolved in *benzene and extracted with aqueous 10% LiOH until the extract is colourless. Evaporation of the *benzene solution under vacuum gives 1-methylnaphthalene [Kloetzel & Herzog J Am Chem Soc 72 1991 1950]. However, neither the picrate nor the styphnate complexes satisfactorily separate 1-and 2-methylnaphthalenes. To achieve this, 2-methylnaphthalene (10.7g) in 95% EtOH (50mL) has been precipitated with 1,3,5-trinitrobenzene (7.8g) and this complex has been crystallised from MeOH to m 153-153.5o (m of the 2-methyl isomer is 124o). [Alternatively, 2,4,7-trinitrofluorenone in hot glacial acetic acid could be used, and the derivative (m 163-164o) is recrystallised from glacial acetic acid]. The 1-methylnaphthalene is regenerated by passing a soution of the complex in dry *benzene through a 15-in column of activated alumina and washing with *benzene/pet ether (b 35-60o) until the coloured band of the nitro compound had moved down near the end of the column. The complex can also be decomposed using tin and acetic-hydrochloric acids, followed by extraction with diethyl ether and *benzene; the extracts are washed successively with dilute HCl, strongly alkaline sodium hypophosphite, water, dilute HCl and water. [Soffer & Stewart J Am Chem Soc 74 567 1952.] It can be freed from anthracene by zone melting [Beilstein 5 IV 1687.]