摘要:

AbstractThe values of the ionization constants of the phenols and anilines in water and water‐ethanol mixtures, determined byGelsema etal.3, have been analysed for the presence of “o‐effects” by the method, devised byMcDanielandBrown7. It appeared that, contrary to the prevailing belief, in the phenol series an “o‐effect” is present, which is attributed to steric hindrance of hydration.The partition coefficients of benzene, toluene, the xylenes and the phenols and anilines derived from these hydrocarbons have been determined for then‐heptane‐water system at 25°.Assuming that the standard free enthalpy of hydration, referred to the solution inn‐heptane, is in first approximation the sum of contributions of the hydrocarbon moiety and the ‐OH and ‐NH2groups, respectively, the latter quantities (ΔG° ‐OH and ΔG° ‐NH2) have been calculated. An analysis for “o‐effects” showed them to be definitely present in the phenol series. In the aniline series the effect is so small that its significancy could not be proved.By combining the “o‐effect” on ΔG° ‐OH and ΔG° ‐NH2(if real) with that on the ionization constants in water, the influence of steric hindrance of hydration by oneo‐methyl group on the standard free enthalpy in aqueous solution could be calculated for the species R‐OH, R‐NH2, R‐O⊖ and R‐NH3⊕. The values obtained were 0.4, 0.1, 0.6 and 0.8 kcal/mole, respectively.Heinen's17recent results on the association of phenols with acetone in carbon tetrachloride solution have also been explai

ISSN:0165-0513    

DOI:10.1002/recl.19660850102

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractA crystalline compound (“tetrathiopentone”, C15H28S4) has been isolated in high yield from the reaction of acetone with hydrogen sulfide in an acidic medium. Its structure was established as, 2,2,4,4,8,8,10,10‐octamethyl‐3,5,7,9‐tetrathiaspiro[5,5]und

ISSN:0165-0513    

DOI:10.1002/recl.19660850103

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractA number of alkyl and cycloalkyl methylphosphonofluoridothionates were prepared by treatment of methylphosphonothioic difluoride with a mixture of one mole equivalent each of the appropriate alcohol and triethylamine in ether or benzene medium. Reaction velocities of the irreversible inhibition of acetylcholinesterase and butyrylcholinesterase were determined and compared with those of the corresponding phosphonofluoridates. A convenient method for the preparation of methylphosphonothioic difluoride is given.

ISSN:0165-0513    

DOI:10.1002/recl.19660850104

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractPhotocurrents in anthracene crystals (with electrolytic electrodes) generated by strongly absorbed light (25000‐30000 cm−1) have their origin exclusively at the surface of the crystal in contact with the positive electrode. Photocurrents observed under illumination of the negative electrode arc the result of reabsorption of fluorescent li

ISSN:0165-0513    

DOI:10.1002/recl.19660850105

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractAcid constants of Dowex A‐1 chelating resin and stability constants of metalresin complexes have been determined, using a special theoretical approach. The differences found between the stability constants do not encourage the use of this resin for the separation of heavy metal

ISSN:0165-0513    

DOI:10.1002/recl.19660850106

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19660850107

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractA characteristic component of butter flavour is 2,3‐dimethyl‐2,4‐nonadien‐4‐olide, the enol lactone of 2,3‐dimethyl‐4‐oxo‐2‐nonenoic acid. Homologues have not been found. The substance which has a strong odour reminiscent of celery and occurs in an amount of about 0.5 mg/kg butter, was called “bovolide”.The elucidation of its structure and its synthesis are described. Also several related compound

ISSN:0165-0513    

DOI:10.1002/recl.19660850108

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19660850109

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractN‐Glycosidic coupling of aldoses and the free amino groups of protein is accompanied by profound modification of the ultraviolet absorption spectrum of the protein partner in the Maillard reaction. The increased extinction coefficient at 250 mμ of protein‐carbohydrate complexes incorporating sites ofN‐glycosidic linkage is largely attributable to effects of denaturation, while absorbancy changes at 325 and 350 mμ are accounted for by side reactions involving the sugar partner only. Specifically, the Maillard reaction between protein and sugar results in the formation of a chromophor at the site of coupling absorbing at 305 mμ.The identification of this chromophor as the 1,2‐enol form of anN‐substituted 1‐amino‐1‐deoxy‐2‐ketose is substantiated by studies of ultraviolet absorption in model systems containing low‐molecular weight pr

ISSN:0165-0513    

DOI:10.1002/recl.19660850110

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractThe isomerisation of cyclopropanone hemiacetal to propionic ester can be suppressed by metal ions such as Ag+and Cu2+. These mild oxidising agents can lead to adipic ester (up to 80%) through dimerisation of a radical CH2CH2COOR (III) detectable by ESR. This radical is not formedviapropionic ester, but by isomerisation of a cyclic radical II, the primary oxidation product of the hemiacetal. With ferric chloride the radical can pick up chlorine to form β‐chloropropionic ester.The reactions are equally facile with cyclopropanone hydrate leading to adipic acid and β‐chloropropionic

ISSN:0165-0513    

DOI:10.1002/recl.19660850111

出版商:WILEY‐VCH Verlag    

年代:1966

数据来源: WILEY