Cs. Chin et al., Synthesis and catalytic activity of water-soluble iridium-sulfonated triphenylphosphine complex. Hydration of nitriles, B KOR CHEM, 20(5), 1999, pp. 535-538
Five coordinated water-soluble iridium(I) complex, IrH(CO)(TPPTS)(3) (1) (T
PPTS = P(m-C6H4SO3Na)(3).xH(2)O) has been prepared from the reaction of IrC
l3. 3H(2)O with TPPTS and HCHO in H2O/EtOH solution. Complex 1 catalyzes th
e hydration of nitriles (RC = N, R = CH3, ClCH2, CH3(CH2)(4), Ph) in aqueou
s solution to give the corresponding amides (RCONH2) at 100 degrees C. The
hydration of unsaturated nitriles (R'C = N, R' = CH3CH = CH, CH3OCH = CH, t
rans-PhCH = CH, CH2 = C(CH3)) takes place regioselectively on -C = N group
to give unsaturated amides (R'CONH2) leaving the olefinic group intact, The
yields of the amides seem to be depending on the electrophilicity of the c
arbon of nitrile: The more the electron withdrawing ability of the substitu
ents on nitriles, the more amides are obtained. The hydration of dinitriles
(NC-R-CN, R = (CH2)(4), (CH2)(6)) With complex 1 initially gives mono-hydr
ation products (NC-R-CONH2) which are slowly hydrated further to give dihyd
ration products (H2NCO-R-CONH2). The hydration of 1,4-dicyanobutane has bee
n found to be somewhat faster than that of 1,6-dicyanohexane.