Thermal reaction of (CH

A study of the thermal reaction of (CH3)2C=C(CH3)2 (23DMB2) in the presence of di-t-butyl peroxide (PODBT) at 389-451 K yielded kinetic data on some reactions of the radicals ˙CH3, (CH3)3C˙C(CH3)2 (1122TMP˙) and (CH3)2C=C(CH3)˙CH2 (112TMA˙).The ratio of the cross-combination ratios of the radicals ϕ(112ΤΜΑ˙,1122ΤΜΡ˙)/ϕ(CΗ3,1122ΤΜΡ˙) and the rate constant for H-abstraction from 23DMB2 by ˙CH3 relative to that of the recombination reaction,˙CH3 + (CH3)2C=C(CH3)2 → СН4 + (СН3)2С=С(СН3)˙СН2 (4)2 ˙CH3 → C2H6 (7)have been determined. The values areϕ(1122TMP˙, 112ΤΜΑ˙)/ϕ˙CΗ3,1122TMP˙) = 0.9 ± 0.3log(k4/k71/2) = (3.74 ± 0.21) - (36.3 ± 2.2)/Θwhere Θ = RT ln 10 and the units are dm3/2 mol-1/2 s-1/2 for k4/k71/2, and kJ mol-1 for the energy of activation

Thermal reaction of (CH

The reaction between the radical ∙CH3 and 2-methylbutene-2 (2MB2) was studied in the temperature range 405-444 K. The ∙CH3 source was di-t-butyl peroxide (PODBT). The rate constants relative to that of recombination were determined for H-abstraction from 2MB2 by∙CH3 and addition of ∙CH3 to 2MB2 :∙CH3 + (CH3)2C=CHCH3 → CH4 + ∙CH2CH=CH(CH3)2 (3)→ CH4 + ∙CH2(CH3)C=CHCH3 (4)∙CH3 +(CH3)2C=CHCH3 → (CH3)2∙CCH(CH3)2 (9)2 ∙CH3 → C2H6 (14)The values arelog[(k3 + 4 /k 14 1/2) = (3.31 ± 0.28) - (34.6 ± 3 .1)/Θlog(k9/k14 1/2) = (3.50 ± 0.32) - (36.5 ± 3.8)/Θwhere Θ = RT In 10 and the units are dm3/2 mol-1/2 s-112 for k3 + 4/k14 1/2 and k9/k14 1/2 and kJ mol -1 for the energy of activation.For the disproportionation to combination ratios o f the 1,1,2-trimethylpropyl radical (112TMP∙), the following value was obtained: Δ2(112TMP∙, 112TMP∙) = 1.2 ± 0.3, where the subscript 2 refers to the formation o f a 2 -olefin as one of the products

Hydrogen bonding interactions in a-substituted cinnamic acid ester derivatives studied by FT–IR spectroscopy and calculations

Intermolecular hydrogen bonding interactions in stereoisomeric cc-substituted cinnamic acid methyl esters (methyl 2,3-diphenylpropenoate, methyl 2-phenyl-3-(2'-methoxyphenyl)-propenoate, methyl 2-(2'-methoxyphenyl)-3-phenylpropenoate and methyl-2,3-bis(2'-methoxyphenyl)-propenoate) were studied by FT-IR spectroscopy and model calculations at the semi-empirical quantum chemical level of theory. Intermolecular hydrogen bonds of C-H...O types were found to be general in the solid stare, but rare in solution. In this hydrogen bond the carbon may be part of either aromatic ring or the olefinic bond. The hydrogen bond acceptor may be the carbonyl oxygen or the oxygen in the methoxy substituent. Modeling helped in determining probable hydrogen bonding sites and their positions and provided with approximate geometric parameters (bond lengths and angles). Pointing out differences between the stereoisomers was also possible