The kinetics and mechanisms of gas phase elimination of primary, secondary, and tertiary 2-hydroxyalkylbenzenes

✍ Scribed by Gabriel Chuchani; Alexandra Rotinov; Rosa M. Dominguez

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 149 KB
• Volume: 31
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/(sici)1097-4601(1999)31:6<401::aid-kin1>3.0.co;2-z

✦ Synopsis

2-Phenylethanol, racemic 1-phenyl-2-propanol, and 2-methyl-1-phenyl-2-propanol have been pyrolyzed in a static system over the temperature range 449.3-490.6ЊC and pressure range 65-198 torr. The decomposition reactions of these alcohols in seasoned vessels are homogeneous, unimolecular, and follow a first-order rate law. The Arrhenius equations for the overall decomposition and partial rates of products formation were found as follows: for 2-phenylethanol, overall rate log toluene for-Ϫ1 Ϫ1 Ϫ1 k (s ) ϭ 12.43 Ϫ 228.1 kJ mol (2.303 RT) , 1 mation log kJ styrene formation log Ϫ1 Ϫ1 Ϫ1 Ϫ1 k (s ) ϭ 12.97 Ϫ 249.2 mol (2.303 RT) , k (s ) ϭ 1 1 kJ ethylbenzene formation log kJ Ϫ1 Ϫ1 Ϫ1 k (s ) ϭ 12.27 Ϫ 226.2 mol (2.303 RT) . 1

2-hydroxyalkylbenzenes show a small but significant increase from primary to tertiary alcohol reactant. Two competitive eliminations are shown by each of the substrates: the dehydration process tends to decrease in relative importance from the primary to the tertiary alcohol substrate, while toluene formation increases.