Adams catalyst acid chlorides

The presence of the epoxide moiety at C-3 and C-4 in excelsine explained the interesting chemical reactions observed earlier. On treatment with acetic anhydride and p-toluenesulfonic acid, excelsine yielded a triacetate derivative, while treatment with acetyl chloride afforded a tetraacetate derivative. On reduction with Raney nickel in methanolic base, excelsine yielded lapaconidine (92), but was inert toward other reducing agents, e.g., lithium aluminum hydride, sodium borohydride, and Adams catalyst. Treatment of excelsine with boiling aqueous hydrochloric acid yielded an epimeric mixture of chlorohydrins with molecular formula C22H34NO6CI. These epimers were hydrolyzed to the crystalline compound C22H33NO6 when treated with aqueous sulfuric acid. This compound formed a tetraacetate derivative for which structure 105 was proposed on the basis of spectral data. 

Two diphenylaminophthalides have been synthesized The 3,3-diphenyl-6-aminophthalide [24] was synthesized in 20% yield by the following sequence of reactions which was patterned after early work °. This series involved nitration of phthalimide, hydrolysis and dehydration to 4-nitrophthalic anhydride, Friedel-Crafts reaction with benzene to 2-benzoyl-5-nitrobenzoic acid, cyclization with thionyl chloride to the pseudoacid chloride, Friedel-Crafts reactions with benzene, and, finally reduction of the nitro group to the amino function with Adams catalyst. 

Adams platinum oxide catalyst is readily prepared from chloroplatinio acid or from ammonium chloroplatinate, and is employed for catalytio hydrogenation at pressures of one atmosphere to several atmospheres and from room temperature to about 90°. Reduction is usually carried out with rectified spirit or absolute alcohol as solvents. In some cases (e.g., the reduction of benzene, toluene, xylene, mesitylene, cymene and diphenyl ), the addition to the absolute alcohol solution of 2-5 per cent, of the volume of rectified spirit which has been saturated with hydrogen chloride increases the effectiveness of the catalyst under these conditions chlorobenzene, bromobenzene, o-, m- and p-bromotoluenes, p-dichloro- and p-dibromo-benzene are reduced completely but the halogens are simultaneously eliminated. Other solvents which are occasionally employed include glacial acetic acid, ethyl acetate, ethyl acetate with 17 per cent, acetic acid or 8 per cent, of alcohol. In the actual hydrogenation the platinum oxide Pt02,H20 is first reduced to an active form of finely-divided platinum, which is the real catalyst allowance must be made for the consumption of hydrogen in the process. 

II. 5).204,205 Unsupported iridium catalysts have been prepared by reducing an iridium oxide of Adams type at 165°C under a stream of hydrogen206 or by reducing iridium hydroxide, prepared by addition of lithium hydroxide to an aqueous solution of irid-ium(III) chloride, at 80-90°C and 8 MPa H2.204 Unsupported and supported iridium catalysts may also be prepared by reduction of iridium(IV) chloride with sodium boro-hydride.207 It is noted that the catalytic activity of deactivated iridium can be almost completely regenerated by treatment with concentrated nitric acid.205... 

The second s3mthesis uses 2-methylpyridine-5-sulfonic acid as starting material. It is converted to 5-hydroxy-2-methylpyridine by potash fusion, methylated and condensed with ethyl chloride in the presence of potassium amide. The product thus obtained is demethylated with hydrobromic acid and hydrogenated in the presence of Adams s catalyst... 

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