摘要:

AbstractThe red‐light photolysis of 3‐chloro‐3‐nitrosopentane was studied in various solvents. Photolysis in isopropanol gave 95% of HCl, ∼ 60% of 3‐pentanone oxime and ∼ 20% of 2‐oximino‐3‐pentanone (not 3‐oximino‐2‐pentanone). Photolysis in benzene gave none of these products but yielded five other products instead (together 95%) and nitrogen. The red‐light photolysis of 1‐chloro‐1‐nitrosocyclododecane was also briefly studied in two different solvents but here solvent effects seem to be less pronounced. Mechanisms are proposed to explain the solvent effects. With bothgem‐chloronitroso compounds only very weak ESR signals

ISSN:0165-0513    

DOI:10.1002/recl.19710900902

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractA series of polyunsaturated fatty acids has been tested on essential fatty acid activity and as precursors of prostaglandins. It was confirmed that biological activity ofall‐cis8,11,14‐trienoates and 5,8,11,14‐tetraenoates is restricted to acids with 19, 20 or 21 carbon atoms.All‐cis8,11,14‐eicosapolyenoates with extra double bonds at positions 2, 3 or 4 are also biologically active, On the other hand, an additional double bond in the ω‐chain of the molecule, e.g. at the 18th position, leads to nearly complete loss

ISSN:0165-0513    

DOI:10.1002/recl.19710900903

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractHydrogenation of skipped polyynoic acids and esters over Lindlar's catalyst in the presence of quinoline proceeds with optimum results in light petroleum, ethyl acetate, or acetone at room temperature, yielding the corresponding all‐cispolyenoic compounds in purities of 90‐99%, depending on the number of triple bonds.For hydrogenations of this type mechanistic schemes are presented, including the formation of ene‐ynoic intermediates. Using Langmuir adsorption and Hinshelwood kinetics, analogue computer simulation showed a simultaneous uptake of more than one H2molecule to be an important step in the reaction route.The formation oftrans‐double bonds occurs onlyviaisomerization ofcis‐dou

ISSN:0165-0513    

DOI:10.1002/recl.19710900904

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractAldehydes can be converted into 1‐alkoxyalkyl carboxylates under mild conditions by reaction with dialkoxymethyl carboxylates in the presence of carboxylic acids. A mechanism has been proposed to explain the appearance of orthoformate during the reaction, and the accelerating effect of this compound on the formation of 1‐alkoxyalkyl carboxylates.Thermostable 1‐alkoxyalkyl carboxylates can be prepared also from acetals and carboxylic acids though in low yields.Higher homologues were obtained from the 1‐alkoxyalkyl acetates by exchange of the acid group in a distillation procedure. In a similar way formates were obtained from butyrates and the formic acid/triethylammonium formate az

ISSN:0165-0513    

DOI:10.1002/recl.19710900905

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe solubilities at 25° of 2.2‐dimethylpropane, 3,3‐diethylpentane and tetraethylsilicane have been determined in mixtures of water with methanol, ethanol, dioxane, acetone and acetic acid. The solubilities of tetramethylsilicane, tetramethylgermanium, tetramethyltin, tetraethyltin and tetrapropylgermanium have been determined in mixtures of water with methanol only.All determinations have been performed using gas chromatography.The differences between the standard chemical potentials of these solutes in their solutions in water and in the mixed or nonaqueous solvents have been calculated.The applicability ofPierotti'stheory to the solutions in water, methanol, ethanol and acetone, and also inN‐methylformamide, has been invest

ISSN:0165-0513    

DOI:10.1002/recl.19710900906

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe difference of standard chemical potentials of KCl in water and in mixtures of water with ethanol, dioxane and acetone has been determined by means of emf measurements on the cell:An improved cell design was used for these measurements.

ISSN:0165-0513    

DOI:10.1002/recl.19710900907

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractA systematic study has been made of the kinetics of the rearrangements of protonated dialkyl ketones, aldehydes and α‐deuterated aldehydes. The rearrangements can be divided into four groups, the relative rates of which, at 25°, are approximately 107: 102: 102: 1, viz. (i) of α‐dibranched aldehydes to α‐mono‐branched ketones, (ii) of α‐monobranched aldehydes to di‐n‐alkyl ketones, (iii) of α‐dibranched ketones, (iv) of α‐monobranched ketones.Whereas the first three groups of reactions proceed by a two‐step process (1,2‐alkyl and/or hydrogen shiftsviaan α‐hydroxyalkyl carbonium ion), the interconversion of α‐monobranched ketones takes place by a four‐step processviatertiary α‐hydroxyalkyl carbonium ions and a protonated α‐dibranched aldehyde.The intramolecular exchange of α‐D and carbonyl‐H in deuterated isobutyraldehyde and propionaldehyde is about ten times slower than the rearrangements under (i) and (ii), respectively. This is due to the lower stability of the intermediate α‐hydroxyalkyl carbonium ions in the former two reactions; intrinsically, hydrogen shifts are faster than alkyl shifts. Other things being equal, the ethyl shift is about four times faster than the methyl shift.Protonated aldehydes are about 9 kcal.mole−1less stable than the isomeric protonated ketones, which is mainly due to the difference in stability of the unprotonated parent compounds. Contrary to recently published results (ref. 13), the difference in pKabetween aliphatic al

ISSN:0165-0513    

DOI:10.1002/recl.19710900908

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe preparations of a series of compounds containing the bis(N.N‐di‐alkyl‐dithiocarbamato)gold(III)‐ion of formula [Au(R2dtc)2]+X−, with R = H, Me. Et,n‐Pr.n‐Bu and Ph, and with X−= Br−, ClO4−, PF6−, AgBr2−, AuBr2−, B(Ph)4−, Au(S2C6H3CH3)2−, and Au(S2C2(CN)2)2−are reported.The C‐N stretching frequencies are measured in the crystalline state as well as in chloroform solutions. These data show that some negative ions have a distinct effect on the C‐N stretching frequency in the solid state, but this effect is absent in chloroform solutions. Since X‐ray studies have shown that these anions are situated near the nitrogen atom of the cation their effect on the C‐N frequencies is due to a polarisation of the C‐N bond.Electric conductivity measurements reveal these complexes to be 1 : 1 electrolytes in nitrobenzene solutions. From the measurements in this solvent several l

ISSN:0165-0513    

DOI:10.1002/recl.19710900909

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

Abstract2‐Methyl‐4‐isopropylidenecyclohexanone (7) can be obtained in good yield from β‐pinene (2) in a 5‐step sequence. Key step is the acid‐catalysed ring opening ofcis‐3‐methylnopinone (5) to give 4‐(l′‐hydroxyisopropyl)‐2‐methylcyclohexanone (6, XOH). Robinson annulation of 7 withtrans‐3‐penten‐2‐one proceeds stereoselectively to give α‐vetivone (10). Similar annulation of the isopropenyl isomer (8) affords 7‐epi‐nootkatone (11). 10 can be

ISSN:0165-0513    

DOI:10.1002/recl.19710900910

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractAn efficient route to optically pure sesquiterpenoids of the nootkatane type is described. Stereoselective Michael‐type addition of (‐)‐3‐methylsabinaketone (9) totrans‐3‐penten‐2‐one is used to create the asymmetric centers at C(4) and C(5) in the tricyclic ketone 12. Practical procedures for the conversion of 12 into (‐)‐α‐vetivone (17) and (‐)‐noo

ISSN:0165-0513    

DOI:10.1002/recl.19710900911

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY