ISSN:0021-8871    

DOI:10.1002/jctb.5010100709

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractTheE1cm.1%values of infra‐red absorptions of picolines in cyclohexane solution vary with the concentration of the solutes. Variation of theEvalues due to slit width effects is not the only factor contributing to the failure of Beer's Law; a second factor is interaction between the solute molecules. Serious errors in infra‐red absorption analysis of picoline mixtures are demonstrated when such interactions are not taken into acco

ISSN:0021-8871    

DOI:10.1002/jctb.5010100702

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractThe instability of conventional Nessler reagents is shown to be the cause of inaccuracy when they are used to estimate ammonia in solution. A critical investigation of the Nessler reaction has resulted in the formulation of a satisfactory, aqueous reagent. Use of this reagent along with gum arabic, which protects the ammonia‐colour‐complex from flocculation, has permitted the problem of interference to be clarified and by incorporating a method for controlling interference a procedure has been worked out for directly nesslerising Kjeldahl digests. When applied to the determination of the nitrogen content of plant material, the procedure is comparable in accuracy and precision to that of a distillation‐titration method. The reagent is sensitive to 5 μg. of ammoniacal nitrogen in solution and the precision of the method is abou

ISSN:0021-8871    

DOI:10.1002/jctb.5010100703

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractThe distribution of perchloric acid between water and pure tributyl phosphate (TBP) was examined as a function of increasing acid concentration in the initial aqueous solution. The solvent extracts were investigated by determinations of increase in volume and measurements of viscosity, density and conductivity. The water content of the tributyl phosphate layers has also been determined. The data conform with the assumption of several consecutive interactions between mineral acids and the highly basic tributyl phosphate extractant. A discussion of the nature of the species existing in, or extracted into, the tributyl phosphate phase is given and it is suggested that there are four main species involved: [(TBP)4,HClO4,(H2O)8]; [(TBP)2,HClO4,(H2O)5]; [(TBP)4,(HClO4)3,(H2O)10] and [TBP,HClO4,(H2O)2·5]. The mechanism of multistage extraction is suggested

ISSN:0021-8871    

DOI:10.1002/jctb.5010100704

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractIn a number of comparative hydrogenation experiments with sucrose as a raw material it is demonstrated that high yields (up to 75%) of distillable polyalcohols (mainly glycerol and 1,2‐propanediol) can be obtained at moderate temperatures (200‐250°) with copper chromite catalysts activated with beryllium oxide. Nickel catalysts are active even at still lower temperatures, especially in the presence of Ca(OH)2; thus 70% of distillable polyalcohols were obtained by hydrogenating sucrose in methanol in the presence of 3·5 wt.‐% of Ca(OH)2and 15% of a nickel‐onkieselguhr catalyst during 105 min. at 195°.The product distribution analysis according to Weber allowed an easy comparison of the experimental results, particularly in regard to the selectivity of the applied

ISSN:0021-8871    

DOI:10.1002/jctb.5010100705

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractThe simultaneous changes in the viscous, elastic, and brittle properties that result from the addition of rubber to bitumen have been investigated for several different types of rubber and bitumens ranging in hardness from 170 penetration to 55 penetration. The results show that the changes in viscosity and low‐temperature extensibility are due, in the main, to the molecular (or near molecular) dispersion of rubber in the bitumen. For a given bitumen these changes are linearly related both to each other and also to changes in softening point, thus giving a simple method of assessing the relative merits of different types of rubber. It is shown that sulphur, added to latex or present in a vulcanised rubber, causes a rapid breakdown of the rubber when it is heated with bitumen. An equi‐viscous basis is suggested for the characterisation of rubberised bitum

ISSN:0021-8871    

DOI:10.1002/jctb.5010100706

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractExperiments are described in which tars have been oxidised in the laboratory under controlled conditions, or weathered in tarmacadam on the road. The tars were analysed at intervals during the oxidation and during the weathering, into fractions according to solubility in a series of solvents of increasing solvent power. Changes in the value of the ratio of certain of the resin fractions have been used for estimating the contribution of oxidation to the hardening of tar under road conditions. The results show that in a tarmacadam made with a low‐aromatic tar the hardening of the binder that occurs on the road is entirely due to oxidation. Oxidation accounts for about half of the hardening of high‐aromatic t

ISSN:0021-8871    

DOI:10.1002/jctb.5010100707

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractInductive effects of groups can conveniently be measured by effective chargesQ—the hypothetical charges which would be required to give the same effect as the groups. Provided the group is not involved in mesomeric interactions, its inductive effect is reduced by a transmission factor (ϵ=0·5) if an extra atom is introduced between it and the site of the reaction. The relative rates of solvolysis of substituted t‐cumyl chlorides can be calculated from the charge distribution of the benzyl anion and other examples are given of the use ofQand ϵ for the estimation of the effects of substitution upon equilibrium and rate con

ISSN:0021-8871    

DOI:10.1002/jctb.5010100708

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010100701

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY