Thermal Decomposition of Acrolein. The Attack of Methyl and t-Butoxy Free Radicals on Acrolein

Abstract

The thermolysis of gaseous solutions of acrolein in the 500-600" region yields principally carbon monoxide, ethylene. propylene, hydrogen, methane, ethane, 1,3-butadiene and 1-butene in decreasing order of importance. The results are rationalized in part by a short chain decomposition of the aldehyde through vinyl radicals for which the unstable acrylyl fragment is a precuisor. Studies of the methyl radical induced decomposition of acrolein at 250" in the gas phase and the f-butyl hypochlorite photochlorination of the aldehyde a t 22" in solution allow rough approximations of kaddltlan/kabbtraction for methyl and t-butoxy free radicals to be made. These estimates are 4 and (max.), respectively.OXAR 51:. STEWAKI) . I XD OGDEN R. PIERCE Vol. 83 glycol column resolved carbon tetrachloride, t-butyl alcohol and t-butyl acrylate from a mixture of acrolein and acetone. The acrolein-acetone pair was resolved on P,B'-oxydipropionitrile. The blip corresponding to t-butyl acrylate was trapped ten times from the triethylene glycol column. Its infrared spectrum was identical with the spectrum of authen-A&nowledgment.-The authors are indebted to >/lr, F. L. ~~d~~~~ for patient assistance with the experimentation.128) This substance was prepared in poor yield from acrylyl chloride and l-butyl alcohol in t h e presence of P\TazCOj; b.p. 56' (80 m m . ) ,The first-order rate constaiits for the acid-catalyzed hydrolysis of sixteen fluoroalkyl-, w-cyanoalkyl-and n-alkylsiliconThe first-The correlations are discussed in terms of polar effects, hydrides have been determined using aqueous ethanolic hydrochloric acid (1.43 N , 95 v o l . -~, ethanol) a t 34.8". order rate constants are correlated using the Taft equation. steric effects and dative r-bonding.

Theoretical study of isomerization and decomposition of propenal

“…No transition states reside on the paths for elimination of a hydrogen atom and of a methyl radical because of radical-radical interactions. 37) in good agreement with the present calculations. Singlet CH 3 CH has two unpaired electrons with spins α and β, on the open-shell carbon atom; the two electrons can interact with the lone-pair electrons of carbon atom, originally donating to the oxygen atom, of C=O to form the double bond of CH 3 CH=CO.…”

Combination Reactions of Propargyl Radical with Hydroxyl Radical and the Isomerization and Dissociation of trans-Propenal

“…Those data are also in good accordance with the already reported data of the trans-propenal decomposition reactions at 148 (182) kcal/mol except for the production of CH 3 CCO + H (P17), which was not mentioned in ref . It is also worth noting that the CO gas-phase product generated in P4, P12, and P13 with the total product-yield contribution of nearly 71% and 66% at 148 and 182 kcal/mol, respectively, is considered to be the dominant species of the IS5-trans dissociation processes; these results agree well with the observed data in the 773–873 K temperature range for the formation of CO in the thermal dissociation of propenal reported by Castro and Rust …”

“…It is also worth noting that the CO gas-phase product generated in P4, P12, and P13 with the total product-yield contribution of nearly 71% and 66% at 148 and 182 kcal/mol, respectively, is considered to be the dominant species of the IS5-trans dissociation processes; these results agree well with the observed data in the 773−873 K temperature range for the formation of CO in the thermal dissociation of propenal reported by Castro and Rust. 66 At both values of E = 148 and 182 kcal/mol, the overall predicted branching ratios show that C 2 H 2 + CO + H 2 , C 2 H 3 + HCO, C 2 H 4 + CO, and CH 2 C + CH 2 O become the major product channels in the decomposition of trans-propenal, for which the first product channel is the most crucial one as compared against the rest channels on the whole PES. This result differs from the above-analyzed assumption confirming that the C 2 H 4 + CO and/or CH 3 CH + CO product channels are the energetically favorable reaction paths.…”

High-yield production of fuel- and oleochemical-precursors from triacylglycerols in a novel continuous-flow pyrolysis reactor

“…When the glycerol backbone is released during triglycerides pyrolysis (the first step in triglyceride decomposition), acrolein (C 3 H 4 O; MW=56 g gmol -1 ) is produced (one mole per mole of triglyceride) which then decomposes to non-condensable C 2 H 4 and CO [27,31,51]. Given this reaction mechanism, the theoretical yield of liquid from soybean oil pyrolysis was calculated to be approximately 93% (w/w) by discounting the estimated mass of acrolein produced from the feed mass.…”