摘要:

Synthesis of Substituted Pyrazolo‐[3,4‐e]‐as‐triazinesSome new substituted pyrazolo‐[3,4‐e]‐as‐triazines (6a—f, 7a‐c) were synthesized by cyclisation of pyrazoline‐4,5‐dion‐4‐isothiosemicarbazones (5a—c) and ‐4‐amidinohydrazones (4a—f) in phenol at 180—200°C. 3‐Ethylmercapto‐7‐phenyl‐pyrazolo‐[3,4‐e]‐as‐triazine (7a) hydrolyses to the 3‐hydroxyderi

ISSN:0021-8383    

DOI:10.1002/prac.19883300112

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractThe reaction of 4‐bromo‐3‐oxo‐butyranilide (1) with KSCN afforded the thiocyanato derivative2. 2‐Dicyanomethylthiazol‐4‐yl‐acetanilide (3) was synthesised by reaction of2with malononitrile. A variety of substituted thiazol‐2‐yl malononitriles were prepared by reaction of3with hydroxylamine hydrochloride, phenylhydrazine and cinnamonitrile derivatives. The structure assignments of the new compounds are based mainly on13C and1H‐n.m.

ISSN:0021-8383    

DOI:10.1002/prac.19883300113

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractEthylene glycol (4‐vinylphenyl‐)‐boronate (2) was copolymerized with technical divinylbenzene to highly crosslinked macroporous polymer (P2). On treatment ofP2with methanol/water, 75% of the polymer‐bound ethylene glycol could be split‐off, under formation of the desired polymer (P1) with free phenylboronic acid groups. The utility ofP1in the solid‐phase synthesis, for instance its conversion to polymer‐supported phenol, and as polymer‐supported protecting group for diols w

ISSN:0021-8383    

DOI:10.1002/prac.19883300114

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

Kinetic H/D Isotope Effect of the Photooxidation of 3,5‐Dimethyl‐1,1‐dioxo‐2‐(p‐tolyl)‐1,2‐thiazine by Singlet OxygenThe hydrogen atoms of the thiazine ring and of the methyl groups of 3,5‐dimethyl‐1,1‐dioxo‐2‐(p‐tolyl)‐1,2‐thiazine1acan be exchanged by deuterium in basic or acidic deutero methanol (CH3OD). In CD3OD/D2SO4the rate of the H/D‐exchange of the different protons of1awas determined by1H‐n.m.r. spectroscopy.A kinetic isotope effect of 1.5–1.8 was determined from the rate of the oxygen consumption and also by using a competitive method. The results are in accordance with an

ISSN:0021-8383    

DOI:10.1002/prac.19883300115

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

Nitration of Some Derivatives of 2‐Methylaminopyridine N‐OxidesThe only stable products obtained from nitrations of 2‐methylaminopyridine N‐oxide and some derivatives, are those resulting from nitration of the pyridine ring. Thus, 2‐methyl‐aminopyridine N‐oxide8is nitrated under mild conditions to yield 2‐methylamino‐5‐nitropyridine N‐oxide9, but not 2‐methylnitraminopyridine‐N‐oxide10is obtained.2‐Methylamino‐4‐nitropyridine N‐oxide1yields 2‐methylamino‐4,5‐dinitropyridine N‐oxide2upon nitration.Chemical reactions which relate known compounds to the new compound

ISSN:0021-8383    

DOI:10.1002/prac.19883300116

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

Protonation and Solvation of Weak Organic Bases. IV.1H‐N.M.R. Spectroscopic Determination of the Basicity of Aliphatic KetonesFrom protonation ratios for a series of methyl and ethyl alkyl ketones1—13with gradually branched alkyl groups in the H2O–H2SO4system, determined by1H‐n.m.r. spectroscopy, basicity and solvation parameters are systematically estimated by application of extrapolation procedures based on the Hammett acidity function H0or the excess ac

ISSN:0021-8383    

DOI:10.1002/prac.19883300117

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

Studies on UV/Vis Absorption Spectra of Azo Dyes. XX. On the Different Substituent Effects on the Absorption Maxima of Hydrazones and Benzenediazonium IonsPMO theory predicts that substituent effects on the absorption maxima of benzenediazonium ions are partly contrary to those in hydrazones. Therefore, it seemed likely that azo coupling products absorbing at shorter wavelengths than the parent diazonium ions should exist. This is confirmed experimentally. The hydrazones4cand5cabsorb significantly hypsochromic than the diazonium ion3c.

ISSN:0021-8383    

DOI:10.1002/prac.19883300118

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

Investigations on the Counter Ion Structure of the Cationics Polymerization of Isobutylvinylether with Iodine Based SystemsThe structure of counter ions of iodine based initiators for the cationic polymerization of isobutylvinylether is elucidated by means of u.v.‐spectroscopy using as model system:Increasing electrophilicity of the cation causes a decrease of the counter ion stability. High concentrations of iodine lead to the formation of polyiodides, as I 5⊖and I 7⊖, respectively.The influence on chain propagation by iodine and monomer concentration as well have been followed by GPC and u.v.‐spectroscopy. Both influences, strongly affects the propagation reaction.Triphenylmethylbromide in conjunction with iodine is a convenient initiating system, realizing a long living and transfer suppressed propagation, when solvents of higher polarity are used. An activated carbon‐halide bond is concluded to be the a

ISSN:0021-8383    

DOI:10.1002/prac.19883300119

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

Acidity and Complex Formation of CurcuminoidsThe stoichiometric acid dissociation constants of curcumin1aand derivatives as well as the stoichiometric stability constants of the Cu(II)‐ and Ni(II)‐complexes of these substances have been determined by pH‐potentiometric titrations in dioxane‐water mixture.The influence of different substituents on the pKa‐values and the stability constants is discussed. The complexing properties of the COCH2CO structural element of the ligands are not significantly changed when the phenyl group is substituted by the styryl group. Solid CuL2‐complexes have been characterized. The coordination of the ester group in the tricarbonyl ligand systems4was excluded b

ISSN:0021-8383    

DOI:10.1002/prac.19883300120

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

O‐Methylation of tert‐Alkylpyrocatecholes. Analytical Method for Determination of the Content of Product Mixtures and Way for Preparation of 4‐tert‐AlkylveratrolesThe O‐methylation of tert‐alkylpyrocatecholes with dimethylsulfate leads to a mixture of substituted guaiacoles6/7,9/10and veratroles5,6which are separated by gas/liquied‐chromatography for analytical purposes. It is also possible to prepare 4‐tert‐alkylsubstituted veratroles5with good yields in this way.On the other hand, the alkylation of veratrole was only successful with lower tert‐alkanols or alkenes. Long‐chained tert‐alkanols fail in this reaction.The analytical and spectroscopical data of some new 4‐tert‐a

ISSN:0021-8383    

DOI:10.1002/prac.19883300121

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY