ISSN:0021-8871    

DOI:10.1002/jctb.5010081112

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractA potentiometric technique is described which is suitable for the estimation of carboxylic acids in a ‘neutral’ solvent, such as a mixture of benzene and methanol, and for the estimation of weaker acids, such as phenols, in basic solvents such asn‐butylamine or a mixture of benzene and ethylene‐diamine.The repeatability of titrations in non‐aqueous media has been briefly examined and is shown to be about ±1.25% of the titration volume for a neutral solvent and rather more for a basic solvent owing to interference by carbon dioxide. Where comparison with an indicator technique was possible, the repeatability of the potentiometric method was not quite so good as that of the indica

ISSN:0021-8871    

DOI:10.1002/jctb.5010081101

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractFour hydroxyl‐substituted benzoic acids and six dihydric phenols have been titrated potentio‐metrically inn‐butylamine solution using potassium methoxide as the titrant.The results are discussed in terms of the electron‐attracting and electron‐repelling properties of the substituent groups in an aromatic ring and of the resultant effects on the acidic strength of the carboryl and hydrox

ISSN:0021-8871    

DOI:10.1002/jctb.5010081102

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractMethods of particle size analysis which are applicable to thoria powders are briefly reviewed and a new method is proposed. In this, thoria is dispersed in a dilute Calgon solution and neutron‐irradiated for a few seconds to produce233Th. An aliquot of the active dispersed phase is placed on the top of a column of aqueous sucrose solution and the mass of thoria deposited after various centrifuging periods is determined by β‐counting through the base of the tube, and from these data a size analysis is obtained. The method is very fast and simple to operate and comparison with the two other centrifugal methods shows excellent agreement. A size analysis of another suitable material, silica, is also demonstr

ISSN:0021-8871    

DOI:10.1002/jctb.5010081103

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractForce‐area isotherms have been obtained for mixed monolayers of arachidic acid and α‐ethyl‐stearic acid on conductivity water and M/400‐CaCl2solution at pH 7.5. There is evidence of molecular interaction on both substrates as the mixed films are always more condensed than an ideal mixture of the two constituents. On M/400‐CaCl2solution, mixed surface films containing more than 75% of α‐ethylstearic acid are fluid at all surface pressures; this indicates that the condensation in the mixed film is due to the van der Waals' forces between the hydrocarbon chains and not to calcium ions.Partial molar areas for the constituents of the mixed films on M/400‐CaCl2solution have been calculated. The small values of partial molar areas obtained for arachidic acid at low mole fractions and low surface pressures are explained by strong van de

ISSN:0021-8871    

DOI:10.1002/jctb.5010081104

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractA study has been made of the production of maleic acid by oxidation of benzene using various catalyst combinations supported on different materials with addition of various amounts of cobalt oxides as promoter. Best yields of maleic acid (50% conversion of benzene) were obtained with a vanadium pentoxide‐molybdenum trioxide (1–2.3:1) catalyst supported on kieselguhr with 5% of cobalt oxide as promoter. The method of preparation of the metal oxides and of pretreatment of the support affected the resu

ISSN:0021-8871    

DOI:10.1002/jctb.5010081105

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractThe oxidation of crotonaldehyde to maleic acid over various catalyst combinations is studied and compared with the oxidation of benzene. About 76% conversion of crotonaldehyde is obtained on a vanadium pentoxide‐molybdenum oxide‐kieselguhr catalyst. The effects of preparation of catalyst and operating conditions on the percentage conversion are described. The presence of water in the crotonaldehyde has little effect on the activity of the cataly

ISSN:0021-8871    

DOI:10.1002/jctb.5010081106

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractThe rational synthesis of the ‘cyclic’ tetranuclearp‐cresol novolak (VIII) from the corresponding resole (VII) which was synthesized from 3‐bromo‐2:2′‐dihydroxy‐5:5′‐dimethyldiphenylmethane (I) has been accomplished in accordance with the scheme given below. A molecular model of the resole (VII) indicated that intramolecular hydrogen bonding of the hydroxyl groups would assist the formation of a configuration which could undergo facile cyclization to give the required novolak (VIII). The infrared absorption spectrum of the ‘cyclic’ tetranuclear novolak showed only the band corresponding to 1:2:4:6‐tetra‐substitution and absence of that due to 1:2:4‐tri‐substitution which was present in the resole (VII). Confirmation of structure was obtained by conversion into a tetra‐acetate which gave a molecular weight determination of the correct order and whose infra‐red absorption spectrum also sho

ISSN:0021-8871    

DOI:10.1002/jctb.5010081107

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractSelf‐discharge of lead‐acid batteries is diminished by deposition of a layer of lead set 20μ thick on the positive grids, but the effect is only temporary and uneconomical thicknesses of lead would be necessary for any lasting effect. Anodizing of the grids had little effect on the rate of self‐discharge.The rôle of antimony in the self‐discharge process is

ISSN:0021-8871    

DOI:10.1002/jctb.5010081108

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractThe spreading of oil on wet coal is shown, theoretically, to depend on two factors: the water/oil/coal contact angle and the oil/water interfacial tension. From these factors two criteria of spreading can be derived: the ‘spreading coefficient’ and the ‘adhesion tension’ relating to spreading on flat surfaces and spreading into capillaries respectively.These criteria were calculated from measurements with pure oils, and with impure oils containing varying amounts of surface‐active agent, to find the conditions most conducive to good spreading.Spreading was not spontaneous under any of the conditions tested, and was assisted by surface‐active substances and flotation frothing agents. The best pure flotation reagents were the worst spreaders, but this is not true of impure reagents. Poor flotation reagents are not poor because of adsorption of the reagent within the coal, since values of adhesion tension obtained were such that spontaneous spreading into cracks could not occur. Oils spread more readily on polished surfaces than on rough surfaces and more easily on high‐rank than on

ISSN:0021-8871    

DOI:10.1002/jctb.5010081109

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY