Group 6 transition metal catalysts (MoCl5, WCl6, MoCl5-Ph4Sn, WCl6-Ph4Sn, Mo (CO) 6-CCl4-hν, W (CO) 6-CCl4-hν etc) polymerized not only monosubstituted acetylenes (e. g., HC≡C-t-Bu) but also disubstituted acetylenes (e. g., CH3≡C_nPr, ClC≡CPh). Group 5 transition metal catalysts (NbCl5, TaCl5 etc), which selectively cyclotrimerize monosubstituted acetylenes, polymerized disubstituted acetylenes (e. g., CH3C≡CPh, CH3C≡CSi (CH3) 3). Thus these catalysts are especially effective to sterically hindered acetylenes for which Ziegler catalysts do not work. The structure and reactivity of monomers, polymer structure, and polymerization mechanism have been discussed. Interestingly, polymers with very high molecular weights (mot. wt. 105-106) were obtained from sterically rather hindered acetylenes (e. g., HC≡C-t-Bu, CH3C≡C-n-Pr, CH3C≡CPh, ClC≡CPh, CH3C≡CSi (CH3) 3). These polymers are generally white (or light yellow), soluble, amorphous, air-stable, electrically insulating, non-paramagnetic solids ; all these properties give a striking contrast to those of polyacetylene.
This article reviews recent results on homogeneous aerobic oxidation explored after 1980. The review is ordered in five sections corresponding to the substrates as follows : (i) oxidation of alkenes comprising of epoxidation, carbonylation, cycloaddition of dioxygen, and allylic oxygenation, (ii) oxidation of arenes including oxygenation of aromatic nucleus and oxidative cleavage of catechols, (iii) oxidation of ketones, nitriles, and nitro compounds, (iv) oxygenation of alkanes, and (v) oxidation of alcohols, amines, and divalent sulfur compounds.
This review deals with the synthetic utilization of the isonitrile compounds ; in particular, the article focuses on the reaction of isonitrile- stabilized carban ions with an array of electrophiles. Emphasis has made on the syntheses of biologically interesting α-amino acids and heterocycles using α-isocyanoacetic acid derivatives as an “anionic amino acid synthon”.
Very recently, the chemistry of the double bonds between the elements more than third period has received extensive attention. This review describes the stabilization by steric protection using bulky group and the physical and chemical properties of the highly reactive low-coordination organophosphorus species such as diphosphenes and the related compounds, phosphaalkenes, imino-phosphines, and phosphacumulenes.
Structural study of neopeptins, inhibitors of fungal cell wall biosynthesis, was accomplished by chemical and spectroscopic evidences. In order to determine the structure of unusual amino acid residue (3-amino-2-oxazetidine-4-carboxylic acid), recent NMR techniques such as WEFT method and homoscalar correlated 2 D 1H NMR (COSY) were applied, which also afforded information concerning conformation of the molecule. Biosynthesis of polyether ionophore antibiotic, cationomycin, was investigated by feeding of 13C-labeled precursors. Unambiguous assignment of 13C NMR of cationomycin labeled with 13C-labeled acetate was made by double quantum coherence (1 D INADEQUATE) and homoscalar correlated 2D 13C NMR (13C-13C COSY, 13C-13C SECSY).
I discussed progressive processing of soap, alkylbenzene, long chain alcohols, α-olefin and synthetic surface active agents connected with foreign situation. Also it is described the changing of inorganic builders, other additives, their formulation and various kinds of continuous sulfation/sulfonation processes by SO3-gas and finally estimated the future trend of synthetic detergent and their related field.