METHYL tert-BUTYL ETHER 1. Exposure Data 1.1 Chemical and physical data 1.1.1 Nomenclature Chem. Abstr. Serv. Reg. No.: 1634-04-4 Chem. Abstr. Name: 2-Methoxy-2-methyl-propane IUPAC Systematic Name: tert-Butyl methyl ether Synonyms: t-Butyl methyl ether; tert-butoxymethane; 1,1-dimethylethyl methyl ether; methyl 1,1-dimethylethyl ether; 2-methyl-2-methoxypropane; methyl tertiary butyl ether; MTBE 1.1.2 Structural and molecular formulae and relative molecular mass C 5 H 12 O Relative molecular mass: 88.15 1.1.3 Chemical and physical properties of the pure substance (a) Description: Colourless liquid with a terpene-like odour (Lewis, 1993; Agency for Toxic Substances and Disease Registry, 1996) (b) Boiling-point: 55.2°C (Lide, 1997) (c) Melting-point: –108.6°C (Lide, 1997) (d) Density: 0.7405 g/cm 3 at 20°C (Lide, 1997) (e) Spectroscopy data: Infrared (prism [46183], grating [31183]) and nuclear magnetic resonance (proton [19010], C-13 [4377]) spectral data have been reported (Sadtler Research Laboratories, 1980). (f ) Solubility: Soluble in water (48 g/L); very soluble in ethanol and diethyl ether (Budavari, 1996; Lide, 1997) (g) Volatility: Vapour pressure: 3.26 × 10 4 Pa at 25°C (Budavari, 1996); relative vapour density (air = 1), 3.1 (Environmental Protection Agency, 1994) (h) Explosive limits: Upper, 8.4 %; lower, 1.65%, by volume in air (Scholz et al., 1990) (i) Octanol/water partition coefficient (P): log P, 0.94 (Hansch et al., 1995) ( j) Conversion factor: mg/m 3 = 3.60 × ppm –339– H 3 C O C CH 3 CH 3 CH 3
