摘要:

On the Chemistry of 5‐Amino‐2‐phenyl‐1,2,3‐thiadiazolium SaltsTreatment of the title compounds1with pyridine yield the phenylhydrazones of the 1,2,4‐thiadiazol‐3,5‐diyl‐glyoxylic acid derivatives4. The amides4a,bcan also be obtained by reaction of the phenylhydrazono cyanacetoamides3a,bwith sulphur in the presence of pyridine. Nitriles react with1to form the phenylhydrazones of the 1,2,4‐thiadiazol‐5‐yl‐glyoxylic acid derivatives6. Reduction of6ayields the 1,2,4‐thiadiazol‐5‐yl‐glycine derivative7. Depending on its condition the reaction of1cwith benzoyl acetonitrile yield either the 1,2,4‐thiadiazole or the 4‐amino‐thiazole derivative (6ior8). From1aand ethyl acetoacetate the phenylhydrazone of the thiazol‐2‐yl‐glyoxylic acid derivative9arises which can be reduced to yield the thiazol‐2‐yl‐glycine derivative10. The addition of1onto isothiocyanates in the presence of pyridine yields the substituted N‐(1,2,3‐thiadiazol‐5‐ylidene)‐thioureas12a,b. Carboxylic acids react with1in the presence

ISSN:0021-8383    

DOI:10.1002/prac.19863280512

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

The Interaction of Donors with Alkylaluminium Halogenides. III. Model Calculations with the CNDO/2‐MethodThe quantum chemical model calculations show, that the Lewis acidity of the compounds (CH3)nAlCl3−n(n = 0…3) decreases with increasing n. The influence of the methyl ligands seems to be additive.The heterolysis of the RX bond (R = H, CH3; X = Cl, OH, NH2, CH3) is promoted by the cooperation of the Lewis acids (CH3)nAlCl3−n. Fox X = OH, NH2, CH3the energy effort is nearly the same, while it is smaller by a third for X = Cl. Before heterolysis the formation of a complex takes place between the Lewis acid and the donor RX. The complex with HCl is more stable than th

ISSN:0021-8383    

DOI:10.1002/prac.19863280513

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

A Simple Route to a New Type of Boron‐containing SpirocompoundsThe reaction of enolizable 1,3‐dicarbonyl compounds6with diol compounds5and boric acid results in a new typ of boron‐containing spiro‐compounds10. By using different substituted5and6more than 40 new spiroboronates10have been prepared and characterized by means of spectroscopic and analytic

ISSN:0021-8383    

DOI:10.1002/prac.19863280514

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Organophosphorus Antioxidants. IV. Chemical Induced Polarization of31P Nuclei in the Reaction of Cyclic Phosphites with Hydroperoxides31P‐n.m.r. CIDNP is observed in the reactions of cyclic o‐phenylene and ethylene phosphites with hydroperoxides. Polarized phosphorus nuclei appear especially in the phosphonate and phosphate regions. Application of Kaptein's rule shows that these products are cage or escape products of secondary or tertiary radical pairs. Solvent molecules are involved in the formation of the tertiary radical pairs.The concentration of the products formed from polarized31P nuclei is very

ISSN:0021-8383    

DOI:10.1002/prac.19863280515

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractDecomposition of cyclohexane and 1‐methylcyclohexane hydroperoxides in cis‐and trans‐1,4‐dimethylcyclohexane in the presence of boric acid esters results in a non‐stereospecific attack at the tertiary CH bonds of the 1,4‐dimethylcyclohexanes. Mixtures of cis‐ and trans‐1,4‐dimethylcyclohexanols are formed in every case. This proves that the attack of the hydroperoxides at the tertiary CH bonds does not proceed by an al

ISSN:0021-8383    

DOI:10.1002/prac.19863280516

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractSecondary trimethylsilyl ethers (2a–d) are not affected by Collins reagent in dichloromethane at 0°C. Primary trimethylsilyl ethers (4a–e), however, are smoothly oxidized to aldehydes (5a–e) under these conditions. In agreement with these observations trimethylsilylated diols or polyols with primary and secondary trimethylsilyloxy groups (6–9) are oxidized selectively by Collins reagent to trimethylsilyloxy aldehydes

ISSN:0021-8383    

DOI:10.1002/prac.19863280517

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractThe molecular geometries in the electronic states S0and T1, heats of formation, singlet‐triplet splitting and transition energies of cumulenes and 1‐ and 2‐aza‐cumulenium cations up to chain lengths of 11 C‐atoms have been investigated by means of MINDO/3, CNDO/S and a modified PPP procedure. As far as experimental data are available their agreement with the theoretical results is satisfactory. This enables the molecular structure, the spectral behaviour and the colour of cumulated chains to be extrapolated up to chains of 20 C‐atoms. The properties of the cumulenes studied are compared with those of polyenes and polymethines and attempts were made to integrate cumulated chains within these classes of unsaturated chai

ISSN:0021-8383    

DOI:10.1002/prac.19863280518

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

13C‐N.M.R. Spectroscopical Analysis of Mixtures of Isomeric Alkyl‐4‐butylmorpholinesMixtures of isomeric alkyl‐4‐butylmorpholines3were prepared by the treatment of several 2,2′‐dichloroalkyl ethers1(from the chlorination of alk‐1‐enes in the presence of ethylene oxide or propylene oxide) with butylamine and distinguished by13C‐n.m.r. The distribution of isomers of3is not changed in relation to

ISSN:0021-8383    

DOI:10.1002/prac.19863280519

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

MO‐LCAO Calculations on Sulfur‐containing π‐Electron Systems. XLIX. Tetramethine Bridged Derivatives of the Oxalic Acid – Novel Coloured Pigments of Indigoid StructureWhereas thioamides react with the oxalylchloride to Δ2‐thiazoline‐4,5‐diones1, which are precursors of the versatile thioacylisocyanate2synthons, the analogous reaction between thioamides and oxalyl‐bis(arylimidchlorides) completely fails. In the case of aliphatic thioamides the intermediate 2‐methyl‐Δ2‐thiazoline‐4,5‐diimides3undergo oxydative dimerization. The poorly soluble products are tetramethine bridged heteroanalogous oxalates4or isomers. The u.v./vis spectra of the blue compounds are in favour with structure4rather than with structure6. This conclusion has been drawn from the results of Pariser‐Parr‐Pople(PPP) type calculations. According to the calculated position of the colour band of the pigments and of different molecular subunits, and the correspondence of their electronic states involved in the excitation, the dye molecules can be thought as consisting of two symmetrically crossed polymethine chains. This structural feature is inhe

ISSN:0021-8383    

DOI:10.1002/prac.19863280520

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

MO‐LCAO Calculations on Sulfur‐containing π‐Electron Systems. L. Synthesis and UV/VIS Spectral Properties of Derivatives of 1H‐Perimidine‐2‐thioncarbonic AcidEsters of the 1H‐perimidine‐2‐dithiocarbonic acid are easily accessible from 1.8‐diamino‐naphthalene and chloroacetyl chloride and subsequent thiolation of the reaction product under mild conditions and alkylation. The dithioesters react with aliphatic and aromatic amines to form thioamides. Both the resulting dithioesters and thioamides are clearly distinguished by their colour from the vast majority of known derivatives of thioncarbonic acids. While dithioesters and thioamides are generally red and yellow, respectively, in solution the corresponding derivatives of the 1H‐perimidine are blue and red, respectively. The detailed examination of the experimental data has revealed that the colour determining longest wavelength absorption bands are due to the π→π* rather than to the n→π* transitions. Due to the efficient mixing of the lowest energy locally excited (LE) state of the heterocyclic moiety and the lowest energy perimidine‐to‐substituent charge transfer (CT) state the low‐intensity longwavelength π→π* transition of perimidine undergoes a pronounced red shift by acceptor substituents of high electron affinity in 2‐position. This interpretation of the deep colour of the 1H‐perimidine‐2‐thiocarbonic acid is in harmony with substituent effects and fully born out by Pariser‐Parr‐Pople(PPP) type calculations completed by additional analyses of electronic state (Baba‐Suzuki‐Takemura analysis

ISSN:0021-8383    

DOI:10.1002/prac.19863280521

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY