ISSN:0165-0513    

DOI:10.1002/recl.19821011001

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractCondensation of 1,3,4‐trimethyl‐1,5‐dihydro‐2H‐pyrrol‐2‐one, prepared in high yield from 3,4‐dimethylpyrrole, with pyrrole‐2‐carboxaldehyde and 1‐methylpyrrole‐2‐carboxaldehyde gives a mixture of Z‐ andE‐1,3,4‐trimethyl‐2,2′‐pyrromethen‐5[1H]‐one (7 and 8) and 1,1′,3,4‐tetramethyl‐2,2′‐pyrromethen‐5[1H]‐one (9 and 10), respectively. TheZandEforms both isomerise thermally upon heating in basic methanol to the same equilibrium state as is observed during the synthesis. Upon irradiation with light (λ>36

ISSN:0165-0513    

DOI:10.1002/recl.19821011002

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe equilibria in the isomerisation of the methylcyclohexenes and methylenecyclohexane have been investigated in the temperature range of 413 to 523 K. ΔrHand ΔrShave been calculated from the experimental data for the following equilibria: methylenecyclohexane ⇄ 1‐methylcyclohexene, 3‐methylcyclohexene ⇄ 1‐methylcyclohexene and 4‐methylcyclohexene ⇄ 1‐methylcyclohexene. The resulting values for ΔrHand ΔrSare respectively: 7.3 ± 1.7, 7.6 ± 0.5, and 6.7 ± 0.4 kJ mol−1and −15.9 ± 0.3, 1.0 ± 1.6 and 1.5 ± 1.4 J mol−1K−1. These data are compared with values cal

ISSN:0165-0513    

DOI:10.1002/recl.19821011003

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractCis‐ andtrans‐2,5‐diallyloxy‐2,5‐dihydrofuran have been prepared by acid catalyzed transacetalization of 2,5‐dimethoxy‐2,5‐dihydrofuran with allyl alcohol. As a by‐product, 1,1,3‐triallyloxypropane was formed from 2‐allyloxy‐2,5‐dihydrofuran intermediates. Thecis/transconfiguration has been determined by NMR (chiral lanthanide shift reagent) and MS (elimination of allyl alcohol). Oxidation of thecisandtranscompounds by potassium permanganate yieldedmeso‐and (±)‐2,2′‐bis(carboxymethoxy)oxydiacetic acid, respectively. The calcium sequestering properties of the latter compounds were superior to those of the acetal polycarboxylate obtained by sucrose oxidation. This is due to the extra steric hindrance encountered for th

ISSN:0165-0513    

DOI:10.1002/recl.19821011004

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA method is described for the oxidation of some 1‐alkyl‐3‐carbamoylpyridinium chlorides by reaction with immobilized rabbit liver aldehyde oxidase. With the 1‐methyl‐, 1‐ethyl‐and 1‐n‐propyl derivatives, only the 1‐alkyl‐1,6‐dihydro‐6‐oxo‐3‐pyridinecarboxamides have been obtained, but with thet‐Bu analogue the corresponding 4‐oxo compound was found as single product. Thei‐Pr derivative gave rise to a mixture of the corresponding 4‐ and 6‐oxo compounds. From the kinetic data some information has been acquired with respect to the enzyme active‐site environment and

ISSN:0165-0513    

DOI:10.1002/recl.19821011005

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractTreatment of the variouscis,trans‐isomers of CH3SCHCHCHCHCH3and CH3SCHCHCH2CHCH2with a slight excess of potassium amide in liquid ammonia, followed by quenching of the solutions thus obtained with ammonium chloride, gives, in all cases, the is isomer CH3SCH2CHCHCHCH2(>90%trans) From the anionic solutions1H NMR spectra have been recorded.Reductive cleavage of the CS bond of the anions CH3SCHCHCHCHCH2⊖with lithium in liquid ammonia, followed by methylation, leads to almost complete recovery of CH3SCHCHCHCHCH3. During this cleavage, the double bond next to sulfur retains its configuration, while the configuration of the other double bond changes fromtranstocis. It remains the same, however, on starting from a (methylthio)pentadiene with acisC3C4 double bond. The ultimate result of the cleavage procedure with CH3SCHCHCH2CHCH2is CH3SCHCHCHCHCH3: the configuration of th

ISSN:0165-0513    

DOI:10.1002/recl.19821011006

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractReaction of iron(II) dioxime compounds with boron trifluoride diethyl etherate gives clathro compounds. When diphenylboron bromide is used as a reagent, boron‐bridged tetragonal dioxime systems can be prepared via a so‐called pre‐clathro intermediate. This intermediate also shows a tendency to rearrange into a clathro compound. The tetragonal boron‐bridged dioxime compounds Fe(DPGBPh2)2(MeIz)2, Fe(DAGBPh2)2(MeIz)2and Fe(DMGBPh2)2(MeIz)2have a structure similar to that of the corresponding hydrogen‐bridged compounds, as deduced from their optical spectra — and for the latter compound, as shown by single crystal X‐ray analysis. They are, however, much more stable towards oxidation. The compounds react with both carbon monoxide and benzyl isocyanide. Coordinated carbon monoxide can be removed by irradiati

ISSN:0165-0513    

DOI:10.1002/recl.19821011007

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe titleN‐nitrosamine, a potent liver carcinogen, was detected in a mineral oil cutting fluid at concentrations up to 60 mg/kg. Identification was performed by gas chromatography/mass spectrometry and by synthesis. The compound is thought to have been formed from formaldehyde, sodium nitrite and an amino alcohol present in the cutting flui

ISSN:0165-0513    

DOI:10.1002/recl.19821011008

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe stability constants of ternary Zn(II), Cd(II), Co(II) or Ni(II) complexes containing 2,2′‐bipyridinyl (Bipy) or 1,10‐phenanthroline (Phen) andN‐(thiobenzoyl)‐N‐phenylhydroxylamine (TBPH) have been determined in 70% (v/v) dioxane/water medium at 30 ± 1°C and at constant ionic strength (0.1 M NaClO4) in a nitrogen atmosphere. A study of the title metal ions in the presence of an equimolar concentration of the two ligands revealed the formation of mixed‐ligand complexes containing a 1:1:1 molar ratio of metal and the two ligands. These ternary complexes are more stable than would be expected on a statistical basis,i.e. the difference, Δlog KM= log Kmamab‐ log Kmmb, is positive. This is discussed on the basis of π‐acceptor qualities of the heteroaromaticN‐base and the occurrence of a co‐operative effect due to the π systems of two ligands bound to the same metal ion. The trend in stability constants of the mixed‐ligand complexes of the title metal ions is found to be Ni>Co>Cd>Zn. Mixed‐ligand complexes formed with 1,10–phenanthroline are found to be less stable than those formed with 2,2′‐bipyridine and this is disc

ISSN:0165-0513    

DOI:10.1002/recl.19821011009

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA rapid and simple method for the determination of pyrite in coal, based upon a two‐step extraction of iron from coal is presented. After milling the coal in a tungsten‐carbide vessel, the non‐pyritic iron is first removed and then the pyritic iron dissolved. This is then followed by AAS analysis. Analysis of pyritic sulfur and total iron in four types of coal demonstrate the reliability of this m

ISSN:0165-0513    

DOI:10.1002/recl.19821011010

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY