Surfactant‐assisted specific‐acid catalysis of Diels–Alder reactions in aqueous media |
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| Authors: | Egid B. Mubofu Jan B.F.N. Engberts |
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| Affiliation: | 1. Chemistry Department, University of Dar es Salaam, Dar es Salaam, TanzaniaChemistry Department, University of Dar es Salaam, P.O. Box 35061, Dar es Salaam, Tanzania.===;2. Physical Organic Chemistry Unit, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands |
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| Abstract: | Surfactant‐assisted specific‐acid catalysis (SASAC) for Diels–Alder reactions of dienophiles 1 and 4 with cyclopentadiene 2 in aqueous media at 32 °C was studied. This study showed that acidified anionic surfactants (pH 2) such as sodium dodecyl sulfate (SDS) and linear alkylbenzene sulfonic acid (LAS) accelerate Diels—Alder reactions. Conversely, under similar reaction conditions (pH 2) these reactions are inhibited by (acidified) cationic surfactants such as dodecyltrimethylammonium bromide (DTAB), dodecyldimethylammonium bromide (DDAB), and dodecylmethylammonium bromide (DMAB). A modest rate acceleration resulting from the surfactant hydrogen‐bonding capacity is also recorded for the Diels–Alder reaction of naphthoquinones ( 6 ) with cyclopentadiene ( 2 ) in aqueous media at 32 °C. Copyright © 2007 John Wiley & Sons, Ltd. |
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| Keywords: | specific‐acid catalysis Diels– Alder reaction surfactant‐type Brø nsted acid micellar catalysis micellar inhibition |
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