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Aqueous‐Phase Nitrile Hydration Catalyzed by an In Situ Generated Air‐Stable Ruthenium Catalyst
Author(s) -
Ounkham Whalmany L.,
Weeden Jason A.,
Frost Brian J.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902224
Subject(s) - catalysis , ruthenium , nitrile , aqueous solution , in situ , chemistry , aqueous two phase system , phase (matter) , photochemistry , chemical engineering , organic chemistry , engineering
RuCl 2 (PTA) 4 (PTA = 1,3,5‐triaza‐7‐phosphaadamantane) is an active, recyclable, air‐stable, aqueous‐phase nitrile hydration catalyst. The development of an in situ generated aqueous‐phase nitrile hydration catalyst (RuCl 3 ⋅3 H 2 O+6 equivalents PTA) is reported. The activity of the in situ catalyst is comparable to RuCl 2 (PTA) 4 . The effects of [PTA] on the activity of the reaction were investigated: the catalytic activity, in general, increases as the pH goes up, which shows a positive correlation with [PTA]. The pH effects were further explored for both the in situ and RuCl 2 (PTA) 4 catalyzed reaction in phosphate buffer solutions with particular attention given to pH 6.8 buffer. Increased catalytic activity was observed at pH 6.8 versus water for both systems with turnover frequency (TOF) up to 135 h −1 observed for RuCl 2 (PTA) 4 and 64 h −1 for the in situ catalyst. Catalyst loading down to 0.001 mol % was examined with turnover numbers as high as 22 000 reported. Similar to the preformed catalyst, RuCl 2 (PTA) 4 , the in situ catalyst could be recycled more than five times without significant loss of activity from either water or pH 6.8 buffer.