Improved synthetic methods

The development of polythiophenes since the early 1980s has been extensive. Processible conducting polymers are available and monomer derivathation has extended the range of electronic and electrochemical properties associated with such materials. Problem areas include the need for improved conductivity by monomer manipulation, involving more extensive research using stmcture—activity relationships, and improved synthetic methods for monomers and polymers alike, which are needed to bring the attractive properties of polythiophenes to fmition on the commercial scale. 

Qindamycin, 7(5)-7-chloro-7-deoxyliQcomycin [18323-44-9] (1, R = H, R = Q), also known as Cleocin, first resulted from the reaction of lincomycin and thionyl chloride (54) improved synthetic methods involve the reaction of lincomycin and triphenylphosphine dichloride or triphenylphosphine in carbon tetrachloride (55). Clindamycin is significantly more active than lincomycin against gram-positive bacteria in vitro, and is absorbed rapidly following oral adnainistration. Clindamycin 2-palmitate [36688-78-5], (6, R = R = OC(CH2) 4CH2), 2-palmitate ester of clindamycin, is... 

PcH2 was obtained for the first time in 1907 as a byproduct during the preparation of 2-cyanobenzamide.50 However, this discovery initiated no interest at that time. In 1927, PcCu was prepared in 23% yield by heating 1,2-dibromobenzene with copper(I) cyanide in pyridine.51 The term phthalocyanine was first used by Linstead in 1933.52 From 1929 to 1939, Linstead et al. elucidated the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines.52 - 61... 

On the basis of the methylmagnesium bromide addition reaction to nitrones, an improved synthetic method of fluorinated tert-butyl amines was accomplished (Scheme 2.146) (573). 

An improved synthetic method for bicydo[5.3.0]dec-l,7-diene-9-one derivatives has recently been reported, in which [RhCl(CO)dppp]2 is utilized as the catalyst (Scheme 16.51) [56]. 

The synthesis of the unsubstituted 2,6-diphenylphenol was first reported in 1939. It was achieved by the treatment of dipheny ether with phenylso-dium in benzene.141 Scheme 13 represents a simplified mechanism for this reaction. Since then, several improved synthetic methods of syntheses, as... 

Many other polymeric systems are of interest in polymer LEDs. Polythiophenes have been known for some time but it was not until improved synthetic methods were developed that their potential was realised. The process involves the reaction of the substituted monomer with FeClj in chloroform solution. After polymerisation has occurred the product precipitates and is isolated and washed. Further special purification methods are required to obtain satisfactorily pure materials. One product, of commercial interest, developed by Bayer is poly(ethylenedioxy)thiophene, known as PEDOT (3.110). This product when doped with polystyrene sulfonate, sold as Baytron P, has been found to be effective as a conducting, hole-injecting layer on the ITO electrode. ... 

Cheun, Y.G., Cho, J.R., and Kim, J.S. (1995) An improved synthetic method of poly(NiMMO) and PGN prepolymers, in Proceedings of the International Symposium on Energetic Materials Technology, American Defense Preparedness Association (ADPA), Arlington, VA, USA, pp. 61-67. 

However, Yokoyama et al. (1994) reported that a ratio between the chemically conjugated and physically entrapped ADR (i.e., DOX) was not determined, and considerable amounts of adriamycin derivatives formed and were incorporated in the micelles. Yokoyama et al. (1998) quantitatively measured the ADR incorporated in the inner core using the improved synthetic method, and analyzed the effects of the ADR contents (both by chemical conjugation and physical entrapment) on micelle stability andn vivo antitumor activity. The copolymer used by Yokoyama et al. (1998) was polyethylene glycol)-fepoly(aspartic acid) block copolymer (PB P(Asp)). The chemical conjugation and physical entrapment methods can be referred to in the earlier section of preparation of polymeric micelles. 

History. Braun and Tschemak [23] obtained phthalocyanine for the first time in 1907 as a byproduct of the preparation of o-cyanobenzamide from phthalimide and acetic anhydride. However, this discovery was of no special interest at the time. In 1927, de Diesbach and von der Weid prepared CuPc in 23 % yield by treating o-dibromobenzene with copper cyanide in pyridine [24], Instead of the colorless dinitriles, they obtained deep blue CuPc and observed the exceptional stability of their product to sulfuric acid, alkalis, and heat. The third observation of a phthalocyanine was made at Scottish Dyes, in 1929 [25], During the preparation of phthalimide from phthalic anhydride and ammonia in an enamel vessel, a greenish blue impurity appeared. Dunsworth and Drescher carried out a preliminary examination of the compound, which was analyzed as an iron complex. It was formed in a chipped region of the enamel with iron from the vessel. Further experiments yielded FePc, CuPc, and NiPc. It was soon realized that these products could be used as pigments or textile colorants. Linstead et al. at the University of London discovered the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines from 1929 to 1934 [1-11]. The important CuPc could not be protected by a patent, because it had been described earlier in the literature [23], Based on Linstead s work the structure of phthalocyanines was confirmed by several physicochemical measurements [26-32], Methods such as X-ray diffraction or electron microscopy verified the planarity of this macrocyclic system. Properties such as polymorphism, absorption spectra, magnetic and catalytic characteristics, oxidation and reduc-... 

Paolo Chini began his work in the late 1950s with the characterization of cobalt carbonyl species involved in the hydroformylation of olefins with cobalt catalysts, and in the course of these studies developed improved synthetic methods for the known cobalt carbonyls Co2(CO)8 and Co4(CO)12 [132]. His next steps were the preparation of the heterometallic hydrido complex HFe-Co3(CO)i2 (isoelectronic to Co4(CO)12) and the corresponding anion [FeCo3(CO)12], both a novelty at that time, and of the new hexanuclear cobalt clusters [Co6(CO)15]2, [Co6(CO)14]4, and Co6(CO)16 [133-139]. This work was followed by the synthesis of carbido carbonyl cluster anions [Co6(CO)i4C], [Co6(CO)15C]2 and [Co8(CO)i8C]2, containing an interstitial... 

As noted above, a major focus of effort in this area has been to develop improved synthetic methods for macrocycles or to blend either properties or receptors <1999T9425, 1996T6713>. Examples of both types are illustrated in the following sections. 

The improved synthetic method was reported [7] in which readily available /w-di-nitrobenzene was subjected to nitro-displacement reaction with various bisphenols. The resulting bis(3-nitrophenyl)arylene ethers were hydrogenated to afford bis(3-aminophenyl)arylene ethers. 

Sato, K-i, Sekiguchi, T, Hozumi, T, YamazaM, T, Akai, S, Improved synthetic method for preparing spiro a-chloroepoxides. Tetrahedron Lett., 43, 3087-3090, 2002. 

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