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Generation and Trapping of Ketenes in Flow
Author(s) -
Henry Cyril,
Bolien David,
Ibanescu Bogdan,
Bloodworth Sally,
Harrowven David C.,
Zhang Xunli,
Craven Andy,
Sneddon Helen F.,
Whitby Richard J.
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201403603
Subject(s) - ketene , chemistry , trapping , thermal decomposition , catalysis , decomposition , amine gas treating , flow chemistry , kinetic energy , photochemistry , alkoxy group , medicinal chemistry , organic chemistry , ecology , physics , alkyl , quantum mechanics , biology
Abstract Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95 % conversion of EtO, i PrO, and t BuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1‐ethoxy‐1‐octyne to be easily estimated ( E a = 105.4 kJ/mol). Trapping of the in‐situ‐generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precursor.