摘要:

AbstractThe problem of 1,2‐asymmetric induction has been studied as Grignard reagents were added to α‐aminoketones. The experimental factors have been modified in terms of the hypothesis of an interaction between the amino function and the Grignard reagents. The variations resulting from these changes have enabled an interpretation to be put forth of the phenomena depending on the equilibrium between a dipolar and a cyclic m

ISSN:0375-9210    

DOI:10.1002/jctb.5020250102

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe best conditions for obtaining selectively diastereoisomeric aminoalcohols have been determined in an example where the combination of environmental and structural effects has controlled the addition of Grignard reagents to α‐aminoketon

ISSN:0375-9210    

DOI:10.1002/jctb.5020250103

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn order to prepare selectively α‐aminoalcohol R*S* diastereoisomers by adding Grignard reagents to the corresponding α‐aminoketones, the influence of the following factors has been studied successively: permutation of substituents: reagents–substrates, complexing nature of the solvent, addition of magnesium salts, and nature of the halogen. In this way a list has been drawn up of experimental conditions leading to selective or specific preparation of aminoa

ISSN:0375-9210    

DOI:10.1002/jctb.5020250104

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractActive carbon was oxidised in several oxidising solutions and measured for its surface acidity, specific surface area, X‐ray diffraction patterns, ESR spectra and gas adsorption isotherms. The favourable oxidising conditions for acidifying active carbon were speculated. Three kinds of steam activated coconut‐shell carbon were treated by solutions of nitric acid, alkaline permanganate, acidic permanganate with nitrate, acidic dichromate and of chlorate in fuming nitric acid. Graphite was similarly treated as a control. When the carbon was oxidised by all the above mentioned reagents except the acidic dichromate, its surface acidity increased unavoidably accompanied by the surface area reduction in almost a linear relation. However, the surface area reduction was extensive in the carbons oxidised by acidic dichromate. Neither the crystalline nor the amorphous carbon fraction was selectively oxidised by any of the oxidants to a significant extent when observed by X‐ray diffraction, probably because of the lower levels of crystallisation in the micelles. On the other hand, the change of free radicals was observed by most of the oxidations which indicated the conformational change of the carbon at molecular level. The improved adsorption of ammonia was observed on the oxidised carbon up to 20 times and that of sulphur dioxide and water vapour to a few times. The adsorption ofn‐hexane was negatively affected by the oxi

ISSN:0375-9210    

DOI:10.1002/jctb.5020250105

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe optimum autoclaving conditions for Portland blast furnace cement of 35% slag content, in the absence as well as in the presence of fine quartz, have been investigated. It was found that maximum strengths were developed in an autoclaving period of 4 h at 230 lb/in2; the strength values obtained for vibrated mortar cubes were 470 kg/cm2for 1 : 3 (W) cement–standard sand mix, and 904 kg/cm2for 1 : 0.5 : 2.5 cement–fine sand–standard sand mix. Strength values for various autoclaving pressures and times are

ISSN:0375-9210    

DOI:10.1002/jctb.5020250106

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe distribution equilibria of hydrochloric, nitric, perchloric, sulphuric and phosphoric acids between aqueous solutions and a solution of tricaprylmethyl‐ammonium chloride in organic solvent have been investigated. The organic phases have been studied by infra‐red and nuclear magnetic resonance spectroscopy. As a result, it is found that at low aqueous acidity the extraction of these acids is governed by the ion exchange reaction, forming the mono‐quaternary ammonium salts of monobasic acids and the mono‐, di‐ (and tri‐) quaternary ammonium salts of di‐ (and tri‐) basic acids, and at higher acidity by the formation of the adducts to quaternary ammonium salts with a

ISSN:0375-9210    

DOI:10.1002/jctb.5020250107

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractVarious mutagenic agents were employed in succession to produce mutant strains ofBacillus subtiliswith improved yields of α‐amylase. The parent strain had previously been selected as a good producer of α‐amylase. Highly productive mutant strains were selected throughout the work as the basis for further treatment. In shake cultures the yields of α‐amylase of the best strains were double that of the parent strain, and in fermentor cultivation the improvement was even

ISSN:0375-9210    

DOI:10.1002/jctb.5020250108

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

ISSN:0375-9210    

DOI:10.1002/jctb.5020250101

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY