摘要:

AbstractBleaching activators are compounds with O‐ or N‐bounded acetyl groups which are able to react with the strongly nucleophilic hydroperoxy anion to yield peroxyacetic acid. The peroxyacetic acid is decomposed in weakly basic media in a bimolecular reaction forming singlet oxygen. The maximum of the decomposition rate of peroxyacetic acid at pH = 8.3 is also the maximum of bleaching activity of systems containing both bleaching activators and sodium perborate; therefore singlet oxygen must play a decisive role in the activated bleaching of textiles during the washing process.Different bleaching activators can be compared both on the basis of their reaction rates with hydrogen peroxide in weakly basic media and on the basis of their reaction rates with piperidine in dioxane. A great number of potential bleaching activators was studied and compa

ISSN:0941-1216    

DOI:10.1002/prac.19923340402

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Polymers from 1,4:3,6‐Dianhydrosorbitol1,4:3,6‐Dianhydrosorbitol and several similar dioles are easily accessible by technical processes. They can be used for the the synthesis of high molecular polyesters, polyurethanes and polycarbonates. The thermal and mechanical properties of the obtained polymers are similar to that of the respective polymers obtained from usual petrochemical raw materials. Also unsaturated polyesters can be prepared and cured by usual methods. Some of the investigated aliphatic polyesters are suitable as polymeric plasticizers for polyvinylchloride. In conclusion, it is therefore possible to replace well known dioles on petrochemical basis by monomers which can be obtained from renewable sources like sta

ISSN:0941-1216    

DOI:10.1002/prac.19923340403

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

A New Method for Selective Introduction of Trifluoromethyl Groups into Heteroaromatic Compounds. Synthesis of TrifluoromethylfuransTransformation of 4,4‐bis(trifluoromethyl)‐1‐oxabuta‐1,3‐dienes (2) into 2‐fluoro‐3‐trifluoromethylfurans (4) can be achieved in a two step procedure by treatment with tin (II) chloride and sodium hydride. The fluorine atom at skeleton position 2 is replaced smoothly by various nucleophiles. The reaction sequence represents a preparatively simple method for the selective introduction of biologically relevant substituents into 3‐trif

ISSN:0941-1216    

DOI:10.1002/prac.19923340404

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Flavins and Chinamoyl Derivatives in Relation to the Light‐induced Leaf Opening inAlbizia julibrissinIn search of blue‐light photoreceptors for light‐induced leaf opening we isolated from the aqueous extract ofAlbizia julibrissinDurazz. two flavins by adsorption on XAD‐4 and separation with HPLC. One sample was identified as riboflavin1a.In the hydrolysate of the second flavin fraction we found another dimethylisoalloxazine with a C5‐side chain. Furthermore we isolated the cinnamoyl derivatives 3‐O‐(4‐hydroxy‐trans‐cinnamoyl) quinic acid2and 3‐O‐(3,4‐dihydroxy‐trans‐cinnamoyl)‐4‐O‐malonyl‐quinic acid3which formed charge transfer complexes with the flavins in the XAD‐fraction. As a model complex we examined the absorption behaviour of the complex between riboflavin and chlorogenic acid. Using the association constant, we calculated the absorption spectrum and could show that a complex between a flavin and a phenolic compound is a possible blue‐light photoreceptor for the light

ISSN:0941-1216    

DOI:10.1002/prac.19923340405

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Synthesis of Fluorinated PolycarbosilanesFluorine containing polycarbosilanes could be obtained by the reaction of the completely halogenated compounds poly(dichlorocarbosilane) and poly(dibromocarbosilane) with fluorinating agents like ZnF2, KHF2, SbF3, NH4F, NH4HF2, HF and LiF.The most successfully applied fluorinating agent was LiF. The substitution reaction of LiF yielded a fluoropolycarbosilane with a fluorine content of more than 30 weight per cent.This fluorinated compound D‐PFC with a high hydrolitic resistance was analytically and spectroscopically investigate

ISSN:0941-1216    

DOI:10.1002/prac.19923340406

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Organophosphorus Antioxidants. XII. Synthesis and N.M.R. Spectroscopy of Organophosphorus Antioxidants and Related CompoundsThe syntheses of various aliphatic, aromatic, sterically hindered, and cyclic organophosphorus compounds (phosphorous acid esters, ester chlorides and ester amides, hydrogen phosphites, phosphonates and phosphates) are reported, and general procedures for preparation are given.The compounds synthesized were investigated by means of31P‐,1H‐ and13C‐n.m.r. spectroscopy, and the chemical shifts measured are l

ISSN:0941-1216    

DOI:10.1002/prac.19923340407

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractA synthesis of 10‐aza‐3,6‐dithia‐4,19‐dinor‐5ξ‐cholestane15by the A→CD route is described. The title CD ring compound1was coupled with heterocyclic A ring synthons: 2‐methylpyridine, 2‐mercaptopyridine, 2‐mercapto‐2‐imidazoline and 2‐mercapto‐2‐thiazoline. In the case of use the latest synthon cyclization of ringBafforded the cholestane analogue15wi

ISSN:0941-1216    

DOI:10.1002/prac.19923340408

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

ISSN:0941-1216    

DOI:10.1002/prac.19923340409

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

ISSN:0941-1216    

DOI:10.1002/prac.19923340410

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

ISSN:0941-1216    

DOI:10.1002/prac.19923340411

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY