The reactions of 4-chloro-2-butanol and 3-chloro-1-butanol with aqueous sodium hydroxide, and 1-chloro-2-propanol, and 2-chloro-1-propanol with isopropyl amine

Kalevi Pihlaja; Kari Aaljoki; Maija-Riitta Lyytinen; Marja-Liisa Huusko; Marjut Hotokka

doi:10.3998/ark.5550190.0012.516

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The reactions of 4-chloro-2-butanol and 3-chloro-1-butanol with aqueous sodium hydroxide, and 1-chloro-2-propanol, and 2-chloro-1-propanol with isopropyl amine

Kalevi Pihlaja; Kari Aaljoki; Maija-Riitta Lyytinen; Marja-Liisa Huusko; Marjut Hotokka

Volume 2011, Issue 5, Commemorative Issue in Honor of Prof. William F. Bailey on the occasion of his 65th anniversary, pp. 188-199

DOI: http://dx.doi.org/10.3998/ark.5550190.0012.516

Paper ID: WB-5940EP

Received on 2010-10-09; Accepted on 2010-11-23; Published on 2011-03-13

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The reactions of 4-chloro-2-butanol and 3-chloro-1-butanol with aqueous sodium hydroxide, and 1-chloro-2-propanol and 2-chloro-1- propanol with isopropyl amine Kalevi Pihlaja,* Kari Aaljoki, Maija-Riitta Lyytinen, Marja-Liisa Huusko, and Marjut Hotokka Department of Chemistry, University of Turku, FI-20014 Turku, Finland E-mail: [email protected] Dedicated to Professor William Bailey on the occasion of his 65th birthday Abstract The total reaction of 4-chloro-2-butanol 1 with NaOH(aq) is dominated (74%) by intramolecular substitution (SNi), besides which bimolecular substitution (SN2, 12%) and 1,4-elimination (i.e. fragmentation, contrary to earlier arguments) exhibit a significant contribution (11%). The total reaction of 3-chloro-1-butanol 2 instead is dominated by 1,4- (72%) and 1,2-elimination (25%), the substitution reactions being just observable (SNi 2% and SN2 1%). In 1 both the +I-effect and the conformational factors in the intermediate ••chloroalkoxy anion favour the SNi-reaction, whereas in 2 the situation is opposite and the location of Cl on a secondary carbon also makes the SNi-reaction less favourable. The relative proportions of 1,4- and 1,2-eliminations for 2 can be explained by thermodynamic basis since the consequent products are more stable than the corresponding products from 1. 1-chloro-2-propanol 3 and 2-chloro-1-propanol 4 both react with isopropyl amine giving the same product, namely 1-isopropylamino-2-propanol, which indicates that the reaction proceeds through the propylene oxide intermediate. Compound 1 also reacted with isopropyl amine predominantly via SNi-reaction, giving first 2-methyloxetane which then further gave 4- isopropylamino-2-butanol, whereas 2 gave 3-isopropylamino-1-butanol through a direct SN2- reaction. Keywords: 1,2- and 1,3-Chlorohydrins, reactions in alkali, kinetics, mechanisms Introduction In alkaline media 1,3-halohydrins can decompose in the following ways:1-3 (1) intramolecular substitution (SNi) leading to the formation of an oxetane;