This review deals with the recent synthetic organic reactions of various types of organic compounds with trivalent thallium salts. Intramolecular cyclization of olefins, oxidation of phenolic compounds and carbonyl compounds, and substitution reaction of aromatic thallium compounds are mainly described.
A number of stereoselective hydrogenations have been known that are catalyzed by Group VIII transition metals or their complexes. In most cases, however, a mixture of stereoisomers results and it is rather a few cases that lead to only one stereoisomer quantitatively or in very high selectivity. In the following are described some recent examples that are highly stereoselective and would be useful for organic syntheses or of interest from the viewpoint of hydrogenation mechanisms. The article covers 1) the hydrogenation of acetylenic bonds; 2) the hydrogenation of olefinic bonds; 3) the hydrogenation of α, β-unsaturated ketones; 4) the hydrogenation of alicyclic ketones; 5) asymmetric hydrogenations.
Recent development (since 1970) in nitro sugar chemistry has been surveyed. The nitro sugars are shown to have great synthetic utilities as the precursors of amino and branched-chain sugars, uloses, nucleosides, and many other important substances, because several synthetic methods of nitro sugars have been developed and the nitro groups are convertible into various other functional groups.
Variety of new techniques for ionizing organic molecules were briefly sammarized in relation to the internal energies of molecular ions. The principle of chemical ionization (CI) and the characteristics of CI mass spectra were described to present the advantage of CI spectra. The influences of proton affinities and hydride affinities of reagent gases and sample molecules were shown in the CI spectra which also give the information about chemical reactions. Isotopically labelled compounds like D2O can be useful reagent gas to obtain the informations about proton affinities of radicals, extent of H - D exchange reaction and structure of compounds. The principle and characteristics of KE mass spectrum (mass spectrum of ions having excess kinetic energy) were also described. Ions with excess kinetic energy (KE ions) are formed mainly from direct cleavage of highly excited parent molecules, so that it is easy to interpret KE mass spectra which give the infomations about functional groups, such as C2H5, CH2OH, CH3CO, CH3CHNH2, CH2CN and also about fragmentation mechanism, effect of internal and translational energies and structure of compounds.
All of the significant uses of propylene oxide are for chemical intermediates. The major uses of propylene oxide are in manufacturing the propylene glycols used in polyurethane and polyerster resins. The oxide also is used in surface active agents, lubricants, and oil demulsifiers. Propylene oxide has long been made by the chlorohydrin process. The process, however, has two disadvantages; the chlorine used is costly and voluminous waste treatment is necessary. Consequently, for many years, considerable efforts have been devoted to more efficient process routes. In 1969, Oxirane Corp. succeeded to produce propylene oxide by an indirect oxidation method. The process uses tertiary-butyl hydroperoxide or alpha-methy benzyl hydroperoxide to oxidize propylene to the oxide, producing about twice as much alcohols as propylene oxide. Now there is a need, therefore, for a more universal process which is environmentally clean and produce only a negligible amount of by products.
The photofading behaviors of the fluorescent whitening agents (F.W.A.) on cellophane film were examined by both spectrophotometry and thin-layer chromatography. F.W.A. examined were four types of N, N'-disubstituted 4, 4'-diamino-stilbene-2, 2'-disulfonates ; benzoylamino type (B) phenylureido type (U), triazinylamino type (D), and triazolyl type (T). It was found that there were two steps in photofading; the rapid fading step and the slower fading step. The rate of the rapid fading step varied depending on the types of F.W.A. in order U>D>B ≥T. It was confirmed that the rapid photofading in the case of B or U type of F.W.A. is mainly attributable to the trans.→ cis photoisomerization.
It has been found that the dimerization of isoprene catalyzed by palladium-tertiary phosphine complexes occurs in the presence of carbon dioxide to give 2, 7-dimethy 1-1, 3, 7, -octatriene, a tail-to-tail dimer, as the main product. In the adsence of carbon dioxide the palladium complexes catalyze the dimerization of isoprene only to low conversions. In addition to the isoprene dimers, there are also the incorporation of small amount of carbon dioxide in the reaction products. The carbon dioxide-incorporated products identified have the structures of five-membered lactone. The proposed mechanism for isoprene-carbon dioxide reaction involves the intermediate having a σ-allyl, π-allyl form.
Alcohols having no side chain at the 2nd-position (RCH2CH2OH) condensed at high temperatures in the presence of alkali phenoxides or alkali naphthyl oxides to give 2-alkyl substituted higher alcohols (RCH2CH2CHRCH2OH) in good yields. In this reaction the corresponding carboxylic acids were scarcely formed.