摘要:

AbstractThe polarity index, retention index, coefficient ϱ and partial Gibbs function of one mole of a solute methylene group and the Sevcik A criterion were determined at different temperatures for some aromatic hydroxyoximes and intermediate ketones by means of gas‐liquid chromatography using n‐alkanes as nonpolar agents and n‐alcohols as polar agents. The relations between these parameters and the relations between the polarity and the compound structure were discussed.In the oxime and ketone molecules the polarity of the hydrophilic groups changes in the following order: OH>NOH>O;and OH>CO>O, respectively. The ketones have less polarity than the oximes. The phenolic hydroxyl group has twice the polarity of the oxime and the carbonyl groups. The chlorine atom at the ortho position in relation to the hydroxyl group sharpl

ISSN:0021-8383    

DOI:10.1002/prac.19853270302

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

β‐Thiocyanatovinylcarbonyl Compounds. XI. Unusual Substituent Effects in the Mass‐spectrometrical Fragmentation of β‐ThiocyanatovinylaldehydesThe mass spectra of homologous Z/E‐isomers and constitutional isomers of β‐thiocyanatovinylaldehydes are discussed. The main fragmentation consisting of HCN‐loss from the molecular ion is influenced by the substituents so that the constitutional and steric isomers can be clearly distinguished by the\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm M - HC}\left. {\overline {\, {\rm N} \,}}\! \right| + /{\rm M + }^ \cdot $\end{document}ratio. Alkyl homologues with a hydrogen atom in γ‐position to the aldehyde group show an unusual intensive CN‐radical loss due to a „hidden hydrogen rearrangement”︁, which was proved b

ISSN:0021-8383    

DOI:10.1002/prac.19853270303

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

1H‐N.M.R.,13C‐N.M.R., and15N‐N.M.R.‐Investigations Concerning Tautomerism of Bispyrazolons of 4,4′‐Methyliden‐bis‐(3‐stearoylamino‐1‐phenyl‐pyrazolin‐5‐on) TypeWith the help of1H,13C and15N chemical shifts of the n.m.r. signals of the structure elements OH, NHCO,13C‐5,15N‐1,15N‐2 and15N‐2‐H and using the coupling constantsnJ(15NH) andnJ(13C15N) (n = 1, 2) of the doubly15N labelled bispyrazolone1, a chelated and an associated species were shown to exist in the slightly polar solvent CDCl3. The chelated bispyrazolone (BC)chcontains one pyrazolone ring in the tautomeric NH form B and the other in the tautomeric OH form C. In the associated bispyrazolone (BB)as, both pyrazolone rings exist in the NH form B. Observation of the time, concentration and temperature dependence of the n.m.r. spectra of1resulted in the detection of complex exchange processes in tautomeric equilibrium. Apart from the intermolecular exchange process (BC)ch⇌ (BB)as, another exchange process (BC)ch⇌ (CB)choccurs, with intermolecular interactions being involved. It has been established that in the case of substitution in the methylidene bridge (2,3) the lefthand side of the equilibrium (BC)ch⇌ (BB)asparticipates in the process to a greater extent than in

ISSN:0021-8383    

DOI:10.1002/prac.19853270304

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Two‐Phase Reaction of 1‐Bromooctane with Sodium Acetate and Potassium Acetate Catalyzed by Diquaternary Ammonium SaltsNew unsaturated diquaternary ammonium salts (diquats) were prepared in two ways from ditertiary amines3and 1‐bromoalkanes or from 1, 4‐dibromobut‐2t‐ene and tertiary monoamines. A comparison of their catalytic ability with that of saturated diquats and with that of corresponding monoquats was made. The reaction of n‐C8H17Br with NaOAc or KOAc in the two‐phase system liquid‐liquid without an additional solvent is catalyzed more effectively by the unsaturated diquats than by the saturated diquats and the monoquats. Most of the used quats catalyze the ester formation from NaOAc more effectively in the system liquid‐liquid, however, the ester formation from KOAc more effectively in the system solid‐liquid; KOAc is generally superior to NaOAc in both systems. Consequently, in the phase‐transfer catalyzed ester formation from alkali acetate and alkyl halides not only the structure of the quat but also the inorganic cation of the acetate have influence on

ISSN:0021-8383    

DOI:10.1002/prac.19853270305

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Photoinduced Electron Transfer between Arenediazonium Cations and AnionsAnions X⊖can act as donors in electron transfer reactions to photoexcited arenediazonium ions. The yield of the arene formed in this reaction increases with decreasing electrochemical oxidation potential E oxDof X⊖(X⊖= BPh4⊖, Br⊖, HOOCCOO⊖, Cl⊖, BF4⊖). The oxidized donor X· (Cl·, ·COO⊖) and aryl radicals Ar· benig intermediates of the reductive dediazoniation of ArN2⊖can be detected by spin trapping with nitrosodurene (ND) and phenyl‐tert‐butylnitrone (PBN). A solvent effect in the electron transfer reaction is interpreted in terms of ion pairing, where the electron transfer is favored by preorientation and a short distance between the electron donor and the acceptor previous

ISSN:0021-8383    

DOI:10.1002/prac.19853270306

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Solvent Effects in the Photoinduced Electron Transfer Reaction of Uncharged Donors with Arenediazonium SaltsIn the photochemical electron transfer reactions to arene diazonium salts no strong Coulomb forces arise but the rate constants possibly vary in dependence on the state of the diazonium salt (tight ion pair in nonpolar solvents or free diazonium cations). This problem is studied in the present work using anthracene and tetracene, respectively, as electron donors. They react in their S1states diffusion‐controlled with ion pairs ArN2⊖BF4⊖, whereas the respective triplet reactions proceed up to 103times more slowly. These rates are not significantly influenced by the dielectric properties of the solvent. Thus, ion pairing of the diazonium salts in solvents of low polarity has no screening effect on the electron transfer.This behavior is explained including electrostatic effects into the MARCUS theory of outer sphere electron transfer processes. No indication of a Marcus inverted region was

ISSN:0021-8383    

DOI:10.1002/prac.19853270307

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Substituent Effects in13C‐N.M.R. Spectra of Diastereomeric Chalcone Dihalogenides. VI. Assignment of Configuration on Chalcone Rhodanohydrins by Solvent Induced Shift of Signals in13C‐N.M.R. SpectraThe erythro configuration of chalcone rhodanohydrins1was determined by comparison of solvent dependent shifts of C‐α and C‐β signals of1and both the erythro and threo isomeres of chalcone chlorohydrins2as standard in13C n.m.r

ISSN:0021-8383    

DOI:10.1002/prac.19853270308

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Iodation of N‐Aryl‐2,4‐dimethyl‐buta‐1,3‐dien‐1,4‐sultamesBy the iodation of N‐aryl‐2,4‐dimethyl‐buta‐1,3‐dien‐1,4‐sultames1with I2/HgO in EtOH/AcOH the 1,2‐thiazine ring is substituted. The monosubstitution occurs on the 1‐position (1a, d) and the disubstitution on the 1,3‐position (3a). By iodine monochloride in CHCl3the sultames1a–dwere substituted in the (C‐2)‐CH3group (4a–d), in contrast also to the results of chlorination and bromination of1. The structure of the products2, 3

ISSN:0021-8383    

DOI:10.1002/prac.19853270309

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

13C‐ and1H‐NMR‐spectroscopical Investigations of 2,9‐substituted FluorenesThe13C‐ and1H‐chemical shifts for a series of 9‐substituted fluorenes and 9‐substituted 2‐nitrofluorenes, where the substituents are various azarenium ions, have been determined, shift data for several other fluorenyl compounds are also presented. The exact assignments of the13C‐signals are possible by comparison of calculated shifts from13C‐data with experimental1H‐values. The substituent effects are discussed in terms of transmissions of electronic interactions. The substituent chemical shifts (SCS) for selective positions of the fluorene system give a linear correlation with the substituent constants σI,F, respectively. An increment model for the calculation of the empirical13C‐chemical shifts of N‐(2‐nitrofluorene‐9‐

ISSN:0021-8383    

DOI:10.1002/prac.19853270310

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

N‐Amination of Isoquinoline Bases3, 3‐Pentamethylene oxaziridine 1 forms an NN‐bond with secondary isoquinoline bases2a–fto give the cyclohexylidene hydrazines3a–f. In some cases nitrogen elimination yielding indane derivatives13b, 13ecompetes with hydrazone formation. The cyclic Schiff'base14and the β‐carboline derivative16can al

ISSN:0021-8383    

DOI:10.1002/prac.19853270311

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY