Comparison of 1-Hexene and n-Hexane in Vapor-Phase Oxidation

Abstract

Products obtained from vapor-phase oxidation of 1 -hexene and n-hexane differ considerably. Hexane is attacked mainly at the second carbon in the chain and gives a mixture of cyclic ethers (largely 2,5-dimethyltetrahydrofuran and 2,4-epoxyhexane), carbonyls (acetaldehyde and formaldehyde), and olefins (C2-Ce). Hexene apparently is attacked all along the chain and gives 1,2-epoxyhexane, C1-C3 carbonyls including acrolein, and hexenals as major products. Minor products from hexene are 2,5-dimethyltetrahydrofuran, 2,4-, 1,3-, and 3,4-epoxyhexanes (all via the abstraction of a hydrogen atom by the intermediate free radical), 2-methyl-5-ethyl-tetrahydrofuran (via the addition of a methyl group to the intermediate free radical), and 2-oxabicyclo [2,2,1 ] heptane (resulting from attack on the terminal methyl group). Hexene, unlike C2-C4 olefins, does not give Ci and Cs aldehydes in equivalent amounts. This work was undertaken to determine exactly how 1hexene compares with lower molecular-weight (C2-C4) olefins and n-hexane on vapor-phase oxidation. All experiments were carried out in the presence of a "rain" of fine particulate inert solids to prevent inflammation and achieve temperature control. Earlier work in this laboratory (Jones et al., 1969a,b) demonstrated that: The major products from C2-C4 olefins consisted of the olefin oxides plus the carbonyl or carbonyls formed by cleavage of the double bond; the inert solids eitherTable I. Distillation of Hydrocarbon-Rich Layer Product from Oxidation of 1-Hexene" Charge: 9232 grams Fractions Column efficiency Fraction Bp range, Ref. index, collected theor. plates6 wt, g °C n™D range

Theoretical studies of three-membered ring compounds Y2H4X (Y = C, Si; X = CH2, NH, O, SiH2, PH, S)

“…Previous calculated geometries of 4a gave Si-C and C-C bond lengths of 1.892 and 1.563 Á (3-21G)12 and 1.848 and 1.588 Á (3-21 G*).34a A CNDO/2 investigation predicted Si-C (C-C) bond lengths of 1.891 (1.509) Á. 13 Among the more interesting structural features are the unusually short Si-Si bond lengths in rings lb-3b, 5b, and 6b: The calculated Si-Si bond lengths of 2b and 3b are actually closer to the double bond length in disilene (2.13 Á47) than to the Si-Si single bond length in disilane (2.36 Á47). Furthermore, the SiH2 (46) Hehre, W. J.; Random, L.; Schleyer, P. v. R.; Pople, J.…”

Theoretical Calculations of the Effects of 2-Heavier Group 14 Element and Substituents on the Singlet−Triplet Energy Gap in Cyclopentane-1,3-diyls and Computational Prediction of the Reactivity of Singlet 2-Silacyclopentane-1,3-diyls

“…40 kcal/mol) are much higher than that of cyclopropane (SE = ca. 27 kcal/mol) . (3) The π-bond energies of CH 2 =MH 2 (M = Si: D C  SiH2 = ca.…”

Chemical and Physical Processes of Hydrocarbon Combustion: Physical Processes

“…By continuing this building-up process to about the ten carbon-atom paraffinic hydrocarbons beyond which no fundamentally different reaction patterns would exist except in details, the specification of product distribution would consist only in statistically specifying the relative rates of primary radical formation. This is so primarily because there are only certain o-heterocycles which are ever formed in significant quantity according to experiments made at this laboratory (Jones et al, 1971(Jones et al, , 1972Digman et al, 1970). These are the 4-, 5-, and 6-member ring-compounds.…”

“…The significance of 0-heterocycle formation is best illustrated by the n -hexane partial oxidation system. This system has been experimentally studied in the work of Jones et al (1971). Perhaps the most significant feature illustrated is the relative abundance with which o-heterocycles may be formed is these systems.…”