摘要:

Thermogravimetric analysis of the reducing chlorination of aluminaThe kinetics of the chlorination of dehydrated alumina with (CO/Cl2) mixtures were studied in the temperature range of 400–900°. The temperature of dehydration of the alumina was shown to be critical for the reaction rates of the subsequent chlorination. Optimal reaction rates could be observed with equimolar (CO/Cl2) mixtures in the range of 600–700°. At higher temperatures, only a very small increase in reaction rates with increasing temperature could be observed which is thought to be due to the influence of gaseous diffusion gradients in the porous alumina and a progressive decrease in surface area. Granulometric as well as scanning electron microscope studies have shown that with progressing reaction the alumina particles become hollow while retaining their outer shape and size up to a high degree of conve

ISSN:0018-019X    

DOI:10.1002/hlca.19790620112

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Reaction of 3‐Amino‐2H‐azirines with Diphenylcyclopropenethione3‐Dimethylamino‐2H‐azirines (4a,4b) react with diphenylcyclopropenethione (8) to give 4(3H)‐pyridinethione derivatives of type10(Scheme 3). The reaction mechanism for the formation of10is given inScheme 3by analogy with a previous reported one [4] [5]. Hydrolysis of the 4(3H)‐pyridinethione10ayields 2‐oxo‐2, 3‐dihydro‐4(1H)‐pyridinethione (11) and reduction of10awith sodium borohydride leads to the 2, 3‐dihydro‐4 (1H)‐pyridinethione12(Scheme 4). The results of the reaction of4a,4band the thione8demonstrate the similarity to the reaction of4a,4band2[5](cf. Scheme 1). In contrast, the reactions of imines of type7awith2and8, respectively, lead to

ISSN:0018-019X    

DOI:10.1002/hlca.19790620113

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractArylnaphthyl ketones condense with diethyl succinate yielding the stereoisomeric half‐esters2a–2dwhich were subjected to a series of reactions leading to 1‐phenylphenanthrene and 1,1′‐binaphthyl derivatives. (E)‐3‐Ethoxycarbonyl‐4‐(4‐methoxynaphth‐1‐yl)‐4‐arylbut‐3‐enoic acids (2b–d) were converted finally into the corresponding naphtho[1,2‐c]fluorenones (9). The structure of the products was established by IR. and UV. spectroscopy. The effect of substituents on the relative proportions of (E)‐ and (Z)‐half‐esters2was determin

ISSN:0018-019X    

DOI:10.1002/hlca.19790620114

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe steroidal components of 2 marine sponges,Terpios zeteki(from Hawaii) andDysidea herbacea(from Australia) were fractionated through a combination of chromatographic methods, including reversed phase HPLC., and were analyzed by a combination of physical methods, including high resolution GC.‐MS. and 360 MHz1H‐NMR.T. zetekicontains 6 conventional 5α‐stanols which comprise 91% of the sterol mixture, and traces (0.5%) of a new C26sterol, 5α‐24‐norcholestan‐3β‐ol. Minor amounts of conventional Δ5‐sterols (6.5%) and of a single Δ4‐3‐ketosteroid (1.5%) were also present. In contrast, the Australian sponge(D. herbacea)contains 3 Δ5,7‐sterols which comprise 1.5% of the sterol mixture, and one new C29sterol, (24Z)‐stigmasta‐5,7,24(28)‐trien‐3β‐ol, as the major component (75%). In addition, minor amounts of conventional 5α‐stanols (0.5%), Δ5‐sterols (5%) and 5α‐Δ7‐sterols (18%) were present in this complex sterol mixture. The possible dietary or en

ISSN:0018-019X    

DOI:10.1002/hlca.19790620115

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Deconjugation of sugars enones. Preliminary CommunicationBranched‐chain sugar enones1and2(R= Ac) deconjugated toposelectively (only theEisomers reacting) to3. The same phenomenon was noted in the case ofZ‐4which gaveE‐5. The kinetic parameters of these reactions favored a concerted mechanism,i.e.a [1, 5]‐sigmatropi

ISSN:0018-019X    

DOI:10.1002/hlca.19790620116

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractA general stereoselective entry to racemic eremophilane and valencane sesquiterpenes,viaa common key intermediate and using an intramolecularDiels‐Alderreaction, is describe

ISSN:0018-019X    

DOI:10.1002/hlca.19790620117

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Abstract6‐Benzylbicyclo [4.4.0]dec‐1‐en‐3‐one (9) and the 2‐methyl homologue (10) underwent a (γ → α )‐1, 3‐benzyl shift to the β,γ‐unsaturated ketones21and22, respectively, when excited in the π π* absorption band. The quantum yield wasca.0.1 at 254 nm for the formation of both products in alkane solvents. These reactions occur specifically from theS2(π, π*) state in competition with its decay to theS1(n, π*) andTstates. The triplet reaction of9, initiated byn→ π* irradiation and by sensitization, was a double‐bond shift to20, whereas no identifiable product was observed from10under these conditions. Direct and acetone‐sensitized irradiations of21and22resulted in oxadi‐π‐methane rearrangements to mixtures ofsyn‐

ISSN:0018-019X    

DOI:10.1002/hlca.19790620118

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Aroma Constituents of the Purple Passion Fruit. Two New Edulan DerivativesThe isolation of (2R*, 4S*, 4aS*, 8aS*)‐4,4a‐epoxy‐4,4a‐dihydroedulan (1), and (2R*, 3S*, 8aS*)‐3‐hydroxyedulan (2), two new constituents of the purple passion‐fruit (Passiflora edulisSIMS), is reported.Racemic epoxide1was synthesized by oxidation of edulan6with peracidic acid, and racemate of alcohol2was obtained by reduction of ketone7, one of the chromic acid oxidation‐prod

ISSN:0018-019X    

DOI:10.1002/hlca.19790620119

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Ethyl (Z)‐4,7‐Octadienoate and (Z)‐3,5‐Hexadienyl Butyrate, two New Aroma Components of the Purple PassionfruitThe isolation of ethyl (Z)‐4,7‐octadienoate (1) and (Z)‐3,5‐hexadienyl butyrate (2), two new and important aroma constituents of the purple passionfruit (Passiflora edulisSIMS) is reported.Ester1was synthesized by two different routes: (1)via a Wittigreaction between the known 4‐oxobutyrate4and 3‐butenylidenephosphorane, and (2) by thermolysis of (Z)‐8‐acetoxy‐4‐octenoate7which was readily accessible from (Z,Z)‐1,5‐cyclooctadiene.Ester2was prepared from the known hex‐3‐yn‐5‐en‐1‐ol (8) by a stereoselective (Z)‐reduction of the triple bond to9, usingRieke's active metallic zinc, followed by esterification.The organoleptic properties an

ISSN:0018-019X    

DOI:10.1002/hlca.19790620120

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe absorption spectra of 11 solid‐state EDA‐complexes of unsaturated hydrocarbon donors with TCNE as acceptor have been studied in the FIR. region (40–400 cm−1). The dominant feature in the spectra is the appearance of a new intense absorption in the region 80–100 cm−1which is assigned to the intra charge‐transfer lattice mode. The (idealized) force constant for this lattice mode is found to be roughly constant for most of the EDA‐complexes and is thus believed to be a measure of the total interaction of donor and acceptor within the crystal site. Force constants differing in magnitude from those of the majority of complexes are traced back to a particular structure of the donor component and/or the EDA‐crystal as a whole. A recently proposed reassignment of theRamanactive fundamentals of pure TCNE is questioned in view of the

ISSN:0018-019X    

DOI:10.1002/hlca.19790620121

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY