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trimethyl Chem.|traɪˈmɛθɪl, -aɪl|
[f. tri- 5 + methyl.]
a. A formative denoting the presence of three methyl groups, CH3, in a compound, as trimethyl-arsine, As(CH3)3, trimethyl-phosphine, P(CH3)3: see also trimethylamine below.
b. spec. denoting the substitution of 3 methyl groups for 3 hydrogen atoms, in the substance designated by the rest of the name; e.g. trimethylbenzene, C6H3(CH3)3, in which 3 methyl groups have taken the place of 3 H atoms in benzene, C6H6; so trimethyl-methane, CH(CH3)3, from methane, CH4, trimethyl-carbinol, C(CH3)3.OH, etc. Also used attrib. as trimethyl phosphate, (CH3)3.PO4. Hence trimeˈthylic a. attrib. in same sense.
1866Roscoe Elem. Chem. xxxi. 281 Trimethylarsine is a colourless liquid. 1868Watts Dict. Chem. IV. 608 Trimethylphosphine is a transparent, colourless, mobile liquid, heavier than water, having a strong refracting power, and an indescribably nauseous odour. 1873Watts Fownes' Chem. (ed. 11) 767 Trimethyl-benzene is susceptible of three isomeric modifications.
Also triˈmethylamine, the tertiary amine of methyl, N(CH3)3, in which all the 3 hydrogen atoms of ammonia, NH3, are replaced by 3 methyl groups; a volatile liquid with a penetrating fishy odour; formerly also called trimethyl ammonia and trimethylia. triˈmethylene, CH2{btr1}{bbr1}{btc1}CH2CH2, a colourless gas; trimethylene-diamine, a poisonous ptomaine.
1857Miller Elem. Chem. III. 210 Trimethylia... This alkali..is found in considerable quantity in the roe of herrings. 1866Odling Anim. Chem. 87 Trimethylamine (CH3)3N, a frequent constituent of stale brine in which herrings and other fish have been pickled. 1872Garrod & Baxter Mat. Med. (1880) 408 The Hydrochlorate of Trimethylamine is a stable compound, in long needle-shaped crystals, very deliquescent, soluble in water and in alcohol. |