Brown, Herbert C.; Okamoto, Y.; Ham, Geo. published the artcile< Rates of solvolysis of the halophenyldimethylcarbinyl chlorides. The effect of halogen substituents upon the rates of electrophilic reactions>, Electric Literature of 112-63-0, the main research area is .
A series of Et halobenzoates, XC6H4CO2Et, was prepared from the free acids by standard esterification methods in approx. 90% yield (X, b.p./mm., nD20, and m.p. of free acid given): o-F, 85.5°/8, 1.4920, 128°; m-F, 84°/9.2, 1.4848, 124.5; p-F, 87.5°/11, 1.4860, 183.5°; p-Cl, 65°/1, 1.5239, 240.5°; o-Br, 135°/15, 1.5436, 150°; m-Br, 131°/17, 1.5428, 154°; p-Br, 129°/15, 1.5460, 255; m-I, 114°/2.1, 1.5830, 187°; p-I, 126.5°/4, 1.5877, 268°. Similarly were prepared the following esters XC6H4CO2Me (same data given): o-Cl, 99°/8.5, -, 141°; m-Cl, 106°/13, -, 154.5°; p-Cl, 112.5°/8, -, 240.5°; o-I, 103.5°/1, 1.6052, 163°. The appropriate ester (0.25 mole) in 150 cc. Et2O added to 0.55 mole MeMgI in 200 cc. Et2O, the mixture decomposed with saturated aqueous NH4Cl and ice, and the Et2O layer worked up gave 70-5% of the corresponding compounds XC6H4C(OH)Me2 (I) (X, b.p./mm., m.p., and nD20 given): o-F, 74.8°/8, 29.30°, -; m-F, 87°/7, -, 1.4995; p-F, 86°/8.2, 37.8, -; o-Cl, 79.2°/2.2, 23.7, 1.5416; m-Cl, 88.0°/2.2, -, 1.5370; p-Cl, 92.5°/3, 43.3, -; o-Br, 112°/5.2, -, 1.5634; m-Br, 104.5°/3.2, -, 1.5602; p-Br, -, 45.6°, -; o-I, 121°/5.5, -, 1.6017; m-I, -, 59-61°, -; p-I, -, 57-7.5°, -. The appropriate I (5 g.) treated with dry HCl until the weight became constant, the lower layer withdrawn, and the upper layer treated with CaCl2 and evacuated gave the corresponding chlorides, XC6H4CClMe2 (II), which were used without further purification. Aqueous 90% Me2CO adjusted with minor amounts of H2O or Me2CO until Me2PhCCl yielded a rate constant identical with that obtained previously (preceding abstract), 100 cc. solvent treated with approx. 1 cc. of the appropriate II, a 5-cc. zero-time sample removed after 10 min., added to 100 cc. Me2CO at 0°, titrated immediately with 0.0305N NaOH and methyl red as the indicator, and 6-7 addnl. samples withdrawn at the appropriate time intervals and titrated gave the desired rate data for the solvolysis of the II (X, rate constants k1 × 105 sec.-1 at 25°, 40, and 55°, relative ratio at 25°, Eact., ΔH++, and ΔS++ given): H, 12.4, -, – (0.600 at 0° and 36.1 at 35°), 1.00, 19.5, 18.8, -12.5; o-F, 0.622, 3.44, 15.8, 0.0502, 20.9, 20.3, -14.4; o-Cl, 0.0975, 0.625, 3.39, 0.00786, 23.0, 22.3, -11.1; o-Br, 0.0753, 0.517, 2.67, 0.00606, 23.1, 22.5, -11.1; o-I, 0.137, 0.839, 4.56, 0.0110, 22.7, 22.1, -11.4; m-F, 0.311, 1.65, 7.39, 0.0251, 20.5, 19.9, -17.0; m-Cl, 0.194, 1.13, 5.25, 0.0156, 21.3, 20.7, -15.1; m-Br, 0.178, 1.06, 5.44, 0.0144, 22.1, 21.5, -12.7; m-I, 0.289, 1.59, 7.22, 0.0233, 20.8, 20.2, -16.1; p-F, 26.5, -, – (1.32 at 0°, 8.44 at 15°), 2.14, 19.4, 18.8, -11.7; p-Cl, 3.78, 18.1, – (0.163 at 0°), 0.305, 20.0, 19.5, -13.6; p-Br, 2.58, -, – (7.83 at 35°, 21.2 at 45°), 0.208, 19.9, 19.2, -15.2; p-I, 3.03, -, – (9.00 at 35°, 24.0 at 45°), 0.244, 19.5, 18.8, -16.0. Within each of the 3 isomeric series, the observed order of reactivity is F > Cl > Br < I. The observed magnitudes of the rate constants, together with the observed reactivity orders, can be rationalized in terms of inductive effect, resonance, and steric inhibition of resonance. Journal of the American Chemical Society published new progress about Halogens. 112-63-0 belongs to class esters-buliding-blocks, and the molecular formula is C19H34O2, Electric Literature of 112-63-0.
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