摘要:

AbstractThe main inhibiting action of dialkyl sulfoxides in the autoxidation of hydrocarbons derives from their ability to form sulfenic acids on thermal decomposition. The sulfenic acids are extremely active radical scavengers, the rate constant of the reaction of sulfenic acid and peroxy radicals being at least 107l.mole−1· S−1at 60°C. In the AIBN‐initiated oxidation of tetralin in the presence of sulfoxides one peroxy radical is scavenged per molecule of sulfenic acid. This inhibition can be described kinetically as a reduction of the rate of initiation by an amount equal to the rate of decomposition of the su

ISSN:0165-0513    

DOI:10.1002/recl.19720911102

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe PMR spectra of 2‐nitroacetanilide and often 4‐alkyl substituted derivatives have been measured. Two about equally stable conformers have been detected for the derivatives with the groups ‐CHPriBut, ‐CHBut2, and ‐C(OH)But2. The conformational isomerism is caused by a hindered rotation about the bond between the alkyl groups and the benzene ring; rotational barriers have been determined of approximately 12, 22, and 21 kcal/mole, respectively. The preferred conformations and the rotational barriers are discussed for the alkyl groups ‐CH2But, ‐CHMeBut

ISSN:0165-0513    

DOI:10.1002/recl.19720911103

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractIntramolecular shielding effects observed in the NMR spectra of the arylN‐(arylsulfonylmethyl)‐N‐methylcarbamates 1‐7 and of phenylN‐hydroxy‐N‐(p‐tolylsulfonylmethyl)carbamate 8 are interpreted in terms of the occurrence of folded conformations in which the aryl rings are in proximity of each other. The 2′,6′‐protons of the ester aryl group are more upfield shifted than the 3′,5′‐protons, whereas the protons of the aromatic ring attached to the sulfonyl moiety experience no significant shifts. These results indicate that the planes of the aryl rings make an angle with each other. In one case (3) the long wave‐length UV absorption was indicative for weak intramolecular CT interaction between the aromatic rings. Stereochemical information concerning the equilibrium conformation around the NCH2bond was provided by the ESR spectra of the nitroxide 19 (derived from 8) at variable temperatures using the magnitude of the β‐H hyperfine splitting constant as a pr

ISSN:0165-0513    

DOI:10.1002/recl.19720911104

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractOxidation ofN,N‐dialkyldithiocarbamato (R2dtc) complexes of Ni(II), Pd(II) and Pt(II) with 3,5‐bis(N,N‐dialkyliminium)‐1,2,4‐trithiolane ion (R4bitt)2+containing compounds and with M(R2dtc)X2(M = Cu, Au; X = Cl, Br) is reported. From the oxidation of Ni(R2dtc)2the componds Ni(R2dtc)3X (X = Cl, Br, FeCl4) were obtained. The oxidation of Pd(R2dtc)2with R4bitt2+Cu2X2−6(X = Cl, Br) resulted in the new compounds [Pd(R2dtc)3]2Cu2X6.The new compound Pt(R2dtc)3CuBr2could be obtained by the oxidation of Pt(R2dtc)2with either (R4bitt)2+Cu2Br2−6or Cu(R2dtc)Br2, or by the reaction of Pt(R2dtc)3Br with CuBr2. The analogous copper chloride compound was prepared from (R4bitt)2+Cu2Cl2−6with Pt(R2dtc)2. The compound Pt(R2dtc)3AuBr2was prepared from Pt(R2dtc)2and Au(R2dtc)Br2. The metal‐sulfur infrared stretching frequencies are in accord with the assumption that in all these compounds the metal atoms Ni(IV), Pd(IV) and Pt(IV) have a D3symmetry. Conductivity measurements showed the platinum complexes to be

ISSN:0165-0513    

DOI:10.1002/recl.19720911105

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractQuantitative determinations of the nucleic acids in normal and atherosclerotic human aortic tissues were carried out. Intima (lesions removed), media (lesions removed), fatty streaks and spots, plaques and atheromas of the thoracic aorta at the various stages of atherosclerosis were separately analysed.A marked decrease was found in the deoxynucleic acid (DNA) level in the intima and the media from stage 0 to stage I. The DNA level in the more advanced lesions was significantly lower than that in the surrounding apparently unaffected tissue.From the observed RNA/DNA ratios it is concluded that the RNA content of the tissue‐cells gradually increases in the course of the diseas

ISSN:0165-0513    

DOI:10.1002/recl.19720911106

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractRed light irradiation of 2‐methyl‐2‐nitrosopropane (t‐BuNO) in benzene in the presence of oxygen with a high O2/t‐BuNO ratio leads mainly to 2‐methyl‐2‐nitropropane. In styrene part of the solvent is also attacked to give benzal‐dehyde and formaldehyde. Similar photolysis in β‐pinene and cyclohexene gives oxidation on the allylic position, leading to mixtures of α‐β unsaturated alcohols and ketones. Because no double bond shift takes place when β‐pinene is oxidized, singlet oxygen is not involved.In all cases, the reactive species seems to be an adduct of oxygen andt‐BuNO, which can add to double bonds (styrene) or abstract allylic hydr

ISSN:0165-0513    

DOI:10.1002/recl.19720911107

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe reaction of chlorokojic acid with dimethylamine yields 2‐(dimethylamino)‐3‐hydroxy‐6‐methyl‐4H‐pyran‐4‐one in addition to the expected 2‐[(dimethylamino)methyl]‐5‐hydroxy‐4H‐pyran‐4‐one. Upon oxidation the former could be converted into 2,3,5‐tri

ISSN:0165-0513    

DOI:10.1002/recl.19720911108

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe reaction of dichlorosulfine (Cl2C = S = O) with diaryldiazomethanes, (XC6H4)2C=N2(X = H, 4‐CH3, 4‐Cl, 3‐OCH3) leads to derivatives of 2‐chlorobenzo[6]thiophene 1‐oxides. The reaction is proposed to proceedviacyclization of an intermediate episulfoxide. Oxidation of 2,2‐dichloro‐3,3‐diphenylthiirane withm‐chloroperbenzoic acid yields 2‐chloro‐3‐phenyl‐benzo[b]thiophene 1,1‐dioxide. This result supports the pro

ISSN:0165-0513    

DOI:10.1002/recl.19720911109

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe mechanism of the conversion of chloropyrazine into imidazole by potassium amide in liquid ammonia has been investigated. It has been proved, using the labelled compounds 2‐chloro‐[1‐15N]pyrazine and 2‐chloro‐[2‐14C]pyrazine, that this ring contraction occurs by a nucleophilic attack of the amide ion on position 3.The synthesis of 2‐chloro‐[2‐14C]pyrazine starting from diethyl malonate labelled in the ethoxycarbonyl gr

ISSN:0165-0513    

DOI:10.1002/recl.19720911110

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe rearrangement of 2,5,5‐ to 2,4,5‐trimethyldihydrofuryl ion, a heteroaromatic rearrangementvia1,2‐methyl and hydride shifts, is reported. The half‐life of the reaction is about 25 minutes

ISSN:0165-0513    

DOI:10.1002/recl.19720911111

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY