C dehydrogenation

The system RuClj(PPh3)3/Kj(C03)/acetone/56°C dehydrogenated secondary alcohols to ketones in some cases acetophenone replaced acetone (c/x-RuCl Cdmso) with PPh3 was also used, though less effectively) [894]. A similar reaction was noted with RuCl3(PPh3)3/paraformaldehyde/toluene/l 10°C [895]. 

Three main types of reactions undergone by these lactim ethers will be discussed in this section. They are (a) hydrolysis, (b) displacement of the alkoxy (or alkylthio) groups by other nucleophiles, and (c) dehydrogenation/aromatization. 

C. Dehydrogenation and Hydrogenolysis of Cyclohexene on Platinum Crystal Surfaces at Low Pressures (35)... 

Reforming Gasolines, naphthas High-octane gasolines, aromatics 850-1000°F 455-535°C Dehydrogenation, dehydroisomerization, isomerization, hydrocracking, dehydrocyclization... 

Miyake and co-workers (40) have published a synthesis of ellipticine that features a novel reductive phenylation of nitroarenes (41) (Scheme 4). Nitration of 5,8-dimethyl-l, 2,3,4-tetrahydroisoquinoline (22) gave an inseparable mixture of nitro compounds 23. Treatment of this mixture with iron pentacarbonyl and triflic acid in the presence of benzene gave a 2 1 mixture of amines 24 and 25. Separation of these isomers and diazotization of each with nitrous acid, conversion to the azide, and thermolysis yielded ellipticine (1) and isoellipticine (27) (5,11-dimethyl-10f/-pyrido[3,4- )]carbazole), respectively, following Pd/C dehydrogenation of the initially formed nitrene insertion product (e.g., 26). The overall yield of ellipticine is 9%. 

Dehydrogenatioa, Vogel ei al. present procedures for the synthesis of tricyclo-[4.4.1.0 ]undeca-3,8-diene (C) by reduction of naphthalene to isotetralin (A), addition of dichlorocarbene (B), and dechlorination (C). Dehydrogenation with DDQ in... 

Efforts were made to synthesize metal derivatives of unsaturated alcohols via three routes (a) by the use of readily available and thermodynamically stable alcohols, (b) by the generation of thermodynamically less stable alcohols in situ followed by coordination to the metal centers (Eq. 192), and (c) dehydrogenation of a metal alkoxide derivative. 

Whereas the cracking reaction rate becomes significant above 700°C, dehydrogenations only take place substantially above 800 to 850°C. Moreover, the processes of the formation of polyaromatic hydrocarbons and coke only occur rapidly at temperatures above 900 to 1000°C. The adoption of long residence times or the elevation of the reaction temperatures hence favor the reaction yielding heavy aromatic derivatives at the expense of the production of light olefins by cracking. 

Elimination El and E2 Reverse of addition, produce >C=C< Dehydrogenate Dehydrate... 

C20H10N3 + HCN + (CN)2 At still higher temperatures, between 640 and 690° C dehydrogenation of nitrogen residues takes place. 

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