摘要:

Structure / Activity Correlations of Hydrogenation CatalystsThe reason for different activities of group VIII metal catalysts in several hydrogenation reactions is unknown. The activity of group VIII metal catalysts decreases in the hydrogenation of crotonaldehyde to butyraldehyde in the following sequence Pd>Pt>Ni>Rh>Co; Ir. However in the hydrogenation of butyraldehyde to butanol the sequence of metals is inversely.The hydrogenations of crotonaldehyde and butyraldehyde proceed as ligand addition reactions. The reaction rate depends on the nucleophilicity of atomically chemisorbed hydrogen. Whereas the reaction rate in the hydrogenation of crotonaldehyde increases, the hydrogenation rate of butyraldehyde decreases with the nucleophilicity of atomically chemisorbed hydrogen.

ISSN:0941-1216    

DOI:10.1002/prac.19923340202

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractA variety of 2,4,6‐tri‐ and 2,4,5,6‐tetrasubstituted 4H‐1,3‐oxazines (7a – i) were synthesized in excellent yields by the reaction of acetylens (5) in the presence of aluminum chloride with N‐[1‐(benzotriazol‐1‐yl)alkyl]amides4, themselves readily prepared from benzotriazole(1)with amides

ISSN:0941-1216    

DOI:10.1002/prac.19923340203

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractThe use of methyl 3‐mercaptopropionate for the conversion of halogenated pyridines to pyridine thiones and thiols is described, and limitations of the reaction discussed. S‐Alkylation and oxidation reactions of the products from these reactions are repor

ISSN:0941-1216    

DOI:10.1002/prac.19923340204

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractThe solid state conformation of the title compound was determined. Conformational analysis based on molecular modelling mechanics allowed the calculation of the energy of the most stable conformers and their comparison with X‐ray conformatio

ISSN:0941-1216    

DOI:10.1002/prac.19923340205

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Abstracto‐Nitrobenzyl tolyl sulfones(1 a – e)react with nitronate anions(2a, b)giving nitroaryl derivatives of nitroalkanes(3)which eliminate nitrous acid giving nitroarylalkenes(4a – f)as final pro

ISSN:0941-1216    

DOI:10.1002/prac.19923340206

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Influence of Strain Energies on the Fragmentation of Isomeric Dimethylcycloheptanes by Electron Impact IonizationThe mass spectra of cis/trans isomeric 1,2‐,1,3‐ and 1,4‐dimethylcycloheptane(1–7)are discussed. The intensity ratio of (M‐CH3)+/(M‐C2H5)+correlates with the strain energies of the isomers. The mass spectra of deuterium – labeled compounds demonstrate only the fragmentation of the methyl groups during the formation of the (M‐CH3)‐ion and ring opening between the substituted carbon atoms of the cycloheptane. Scrambling processes

ISSN:0941-1216    

DOI:10.1002/prac.19923340207

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

On the Regio‐ and Stereoselectivity of Nucleophilic Thiol Additions to PolyinesNucleophilic thiophenol additions to α,ω‐diphenyl polyines Ph‐(CC)n‐Ph (n = 2–4)(1–3)take a regio‐ and stereoselective course. The well‐defined, crystalline addition products bind the phenylthio group in terminal position of the aliphatic chain, the resulting C, C‐double bonds of the mono‐(4, 6, 8)and bis‐addition products(5, 7, 9)are (Z)‐configurated, as unequivocally p

ISSN:0941-1216    

DOI:10.1002/prac.19923340208

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

About the Synthesis of 6‐nitro‐substituted 2H‐Benzo[b]thiopyran Derivatives Starting from 2‐Mercapto‐5‐nitro‐benzaldehydeBenzene derivatives useful as C3S‐building blocks for the synthesis of 2H‐benzo[b]thiopyrans are not easily available. The synthesis starting with 2‐chloro‐benzaldehyde via 2‐chloro‐5‐nitrobenzalde‐hyde to 2‐mercapto‐5‐nitro‐benzaldehyde‐tert‐butylimin1band its cyclisation to 2H‐benzo[b]thiopyrans (2a – h) and (3a – d) is described. By reaction with acceptor substituted alkenes, e.g. acroleine or ω‐nitrostyrene respectively 2‐chloro‐propenes, e.g. substituted ß‐chloroacroleines or 2‐chloro‐propene‐1,3‐dicarboxylates the compounds2a – hand3a – dare obtained. Vilsmeier

ISSN:0941-1216    

DOI:10.1002/prac.19923340209

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Reactions of Aromatic Nitriles with Diacyl DichloridesDicarbonic acid dichlorides react with aromatic nitriles in the presence of SbCl5to give dicationic bis(1,3,5‐oxadiazinium) salts1.Reaction of1with ammonia or hydrazine yields derivatives of bis(1,3,5‐triazine) (2) or bis(1,2,4‐triazole

ISSN:0941-1216    

DOI:10.1002/prac.19923340210

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

Coronands with 1,2‐Dithio‐ethene Units. II. Crystal Structures of the Two Crown Thioethers 8,9‐Dicyano‐8,9‐didehydro‐7,10‐dithia‐[12]crown‐4 and 11,12‐Dicyano‐11,12‐didehydro‐10,13‐dithia[15]crown‐5The structures of the title compounds have been determined by X‐ray analysis. Both thioethers crystallize in the monoclinic system with the following crystal data. Dithia‐[12]crown‐4: a = 751.7(1), b = 1010.4(1), c = 1639.8(2) pm, β = 95.08(1)°, Z = 4, space group P21/n; dithia[12]crown‐5: a = 1169.9(3), b = 916.7(3), c = 1414.1(4)pm, β = 92.51(2)°, Z = 4, space group P21/c. The structures were refined to final R = 0.048 (Rw= 0.031) and 0.040 (0.046), respectively. They are characterized by their structural parameters (bond lengths and angles, torsion angles, l.s. planes) and discussed in special consideration of the ring conformation and the

ISSN:0941-1216    

DOI:10.1002/prac.19923340211

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY