L imes

A large number of reports have concerned transfer hydrogenation using isopropanol as donor, with imines, carbonyls-and occasionally alkenes-as substrate (Scheme 3.17). In some early studies conducted by Nolan and coworkers [36], NHC analogues of Crabtree catalysts, [Ir(cod)(py)(L)]PF,5 (L= Imes, Ipr, Icy) all proved to be active. The series of chelating iridium(III) carbene complexes shown in Scheme 3.5 (upper structure) proved to be accessible via a simple synthesis and catalytically active for hydrogen transfer from alcohols to ketones and imines. Unexpectedly, iridium was more active than the corresponding Rh complexes, but... 

Cahonic iridium complexes bearing imidazol-2-ylidene hgands were applied as TH catalysts by Hillier et al. [48]. Here, [lr(cod)(py)(L)]Pp6 (L= IMes, l,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (53a), IPr, l,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (53b) and ICy, l,3-bis(cyclohexyl)imidazol-2-ylidene (53c) were employed as catalysts for TH from 2-propanol to various unsaturated substrates, and compared to [lr(cod)(py)(PCy3)]PF6 and complexes formed in situ from [Ir(cod)(py)2]PF,5 and diazabutadienes (RN=CHCH=NR, DAB-R R = cyclohexyl, DAB-Cy 2,4,6-trimethylphenyl, DAB-Mes adamantyl, DAB-Ad 2,4,6-trimethoxyphenyl, DAB-trimethoxyphenyl). AH complexes were achve catalysts for the TH of acyclic ketones, with complex 53c being the most achve, showing 100% conversion of BuC(0)Me and PhC(0)Ph in 25 and lOmin, respechvely, using 0.025 mol% of catalyst and KOH in PrOH at reflux (Scheme 4.20). 

Description of Present Condition Description of Change l iming For Change ... 

A similar run on a scale 3.3 times as large with a 3-hour additii m l ime gave the ketone in 74% yield. 

The CNDO, INDO and NDDO methods use a combination of (1) and (2) tor assigning parameters. Some of the non-zero integrals are calculated from the atomic orbitals, others are assigned values based on atomic ionization potentials and electron affinities. Many different versions exist they differ in the exact way in which the parameters have been derive/l. ime nf the names n.s.snriatpfl with these methods are. r.NDO/1, f NDO/2.,... 

Treatment oftheRu hydride [RuHCl(CO)(PCy3)] (67) with a free carbene such as IMes proceeds by the easy and selective phosphine displacement and formation of complex (68) (equations). At the time of this article, this synthetic pathway has been extended to analogs [(IPr)RuHCl(PCv )l [(IMes)RuHCl(PPh3)], and [(SIMes)RuHCl (PPh3)]... 

Desulfurization with Dry l.ime Limestone or lime or dolomite (CaCOs MgCOs) in a fluidized bed coal combustor reacts with SOj in... 

C. N/jACKSON, Jr and F. GORIS, Plutoidum Waste Drum Monitor, R L-IME 73-13, Westingiiouse HaMord Company (January 1973). 

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