Hydrogenation quantitative

The cationic complex [Rh(DiPFc)(COD)]OTf was discussed earlier as being an excellent catalyst for the hydrogenation of aldehydes under mild conditions. Under similarly mild conditions (25 °C, 4 bar H2, SCR 450, 4h, TOF 110h 1), a range of ketones was hydrogenated quantitatively (Fig. 15.9) [13]. 

The reaction was first conducted with success on sucrose [82], The degree of substitution (DS) obtained was controlled by the reaction time. Thus, under standard conditions (0.05% Pd(OAc)2/TPPTS, NaOH (1 M)/iPrOH (5/1), 50 °C) the DS was 0.5 and 5 after 14 and 64 h reaction time, respectively. The octadienyl chains were hydrogenated quantitatively in the presence of 0.8-wt.% [RhCl(TPPTS)3] catalyst in a HjO-EtOH (50/10) mixture, yielding a very good biodegradable surfactant (surface tension of 25 mN m-1 at 0.005% concentration in water) [84]. Telomerization reaction was also conducted with success on other soluble carbohydrates such as fructose, maltose, sorbitol and /i-cyclodextrin. 

Over Ni-kieselguhr (eq. 5.35, A),121 copper-chromium oxide (eq. 5.35, B)7 and Raney Ni (eq. 5.35, C)122 in ethanol, ethyl acetoacetate is hydrogenated quantitatively to ethyl 3-hydroxybutyrate under the conditions described in eq. 5.35. 

The Ox group can be removed by reduction, either by palladium-catalyzed hydrogenation (quantitative) or by use of sodium in liquid ammonia (75-85% yield). The Ox group can also be cleaved by oxidation with excess m-chloroperbenzoic acid followed by hydrolytic workup (70%). Simple Ox dipeptides have been prepared using l-ethyl-3-(3 -dimcthylaminopropyl)carbodiimide hydrochloride (I, 371). The free dipcpiidcs... 

A 1 wt.% Pd 8 catalyst with di[2,9-(2-methylbutyl)]-l,10-phenanthroline-pro-tected clusters on active carbon hydrogenates acetophenone to phenylethanol at room temperature and at a pressure of 0.1 MPa of hydrogen quantitatively with a TOF value of 45.5 h". Substitution of the 1,10-phenanthroline by (-)-cinchoni-dine ligands leads to an almost complete deactivation of the catalyst. Even temperatures of 60 °C and hydrogen pressures up to 10 MPa do not change the catalyst s activity. On the other hand, the same (-)-cinchonidine-protected eight-shell Pd clusters catalyze the hydrogenation of various unsaturated carbonic acids. 

In this particular example, shown in Scheme 12.9, isophorone can be hydrogenated quantitatively by the commercially-available catalyst, Deloxan AP II 5 %... 

Cotarnine, C H NO,.—This compound is converted by the electrolytic hydrogen quantitatively into pure hydro-cotarnine,... 

Atactic 1,4-polybutadiene and syndiotactic 1,2-polybutadiene can be hydrogenated at 100°C and 50 bar pressure of hydrogen with a soluble catalyst [(Ph)3-P]3RhQ[. Complete saturation of double bonds results [52]. Butadiene aciylMiitrile copolymers can also be hydrogenated quantitatively with... 

With this diphosphine many other substrates were hydrogenated quantitatively and in high enantioselectivity. 

Conjugated unsaturated aldehydes are hydrogenated quantitatively to saturated aldehydes with cobalt catalyst under hydroformylation conditions. 

Catalyst exhaustion is first indicated by the incomplete hydrogenation of ethylene dichloride, while ethylene dibromide and the lead alkyls are still hydrogenated quantitatively. 

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