ISSN:0165-0513    

DOI:10.1002/recl.19961150302

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe series ofN‐alkyl‐,N‐cycloalkyl‐,N‐allyl‐,N‐benzyl‐, andN‐phenyl‐[2.2]paracyclophane‐4,15‐disulfonimides4b − 4mwas synthesized, starting from [2.2]paracyclophane ([2.2]PCP) (1). The initial step is sulfonation of1with chlorosulfuric acid to give [2.2]PCP‐4,15‐disulfonic anhydride (2) in 97% yield. Subsequent reaction of2with the appropiate primary amine quantitatively affords the corresponding alkylammonium 4‐(alkylsulfamoyl)[2.2]PCP‐15‐sulfonate salt (3) which, upon treatment with phosphoric anhydride in dichloromethane, gives the correspondingN‐alkyl[2.2]PCP‐4,15‐disulfonimide4in yields up to 56%. The parent [2.2]PCP‐4,15‐disulfonimide (4a) was obtained by pyrolysis ofN‐isopropyl‐ (4d),N‐cyclopentyl‐ (4h), andN‐cyclohexyl[2.2]PCP‐4,15‐disulfonimide (4i) at 200°C for 20 min in almost quantitative yields with simultaneous expulsion of the corresponding alkene.As determined by X‐ray analysis, the distances between the twop‐phenylene rings are the same for the 4,15‐disulfonimide4aand the corresponding 4,15‐disulfonic anhydride2, but they are both significantly different from those of theN‐isopropyl derivative4d. The sum of the three bond angles around N is ≈︁ 5° smaller for4dthan4aas result of non‐bonded interaction between the methyls of the isopropyl and the neighbouring sulfonyl oxygens. Evidence for non‐bonded interaction was also obtained from dynamic1H‐NMR studies on theN‐cyclohexyl andN‐phenyl derivatives4iand4l, the barrier of rotation around the C‐N bond of4lat 353K,i.e.the temperature of coalescence, being 71 kJ.mol−1.Pyrolysis of crystals ofN‐isopropyl‐,N‐cyclopentyl‐ andN‐cyclohexyl‐[2.2]PCP‐4,15‐disulfonimide (4d,4hand4i) in an argon or nitrogen atmosphere at 200‐210°C for 20 min leads to the formation of [2.2]PCP‐4,15‐disulfonimide (4a) in yields of>95% under the simultaneous expulsion of the corresponding alkene. Under the same conditions the correspondingN‐propyl,N‐cyclopropyl andN‐allyl derivatives4c,4eand4fwere found to be stable.The homogeneous thermolysis of theN‐alkyl[2.2]PCP‐4,15‐disulfonimides4c − 4iin DMSO as solvent, leading to the formation of [2.2]PCP‐4,15‐disulfonimide (4a), was studied quantitatively and appeared to exhibit first order kinetics. At 105‐150°C, the first order rate coefficients decrease in the orderN‐cyclopentyl (4h)>N‐cyclohexyl (4i)>N‐isopropyl (4d)>>N‐allyl (4f)>>N‐propyl (4c); theN‐cyclopropyl derivative4edoes not yield any disulfonimide4a. The mechanism of the thermolysis of theN‐alkyl[2.2]PCP‐4,15‐disulfonimides is discussed, and the differences in rate are explained in terms of (i) diffe

ISSN:0165-0513    

DOI:10.1002/recl.19961150303

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe reactions of the HO−, CH3S−, CH2S−and CH2 C(CH3)CH2−ions with three ketones (CF3COR; R  CH3, CF3, C6H5) and three esters of trifluoroacetic acid (CF3CO2R; R  CH3, C2H5and C6H5) have been studied with use of Fourier Transform Ion Cyclotron Resonance (FT‐ICR) mass spectrometry. All four negative ions react exclusively by proton transfer with CF3COCH3. With the other substrates, the HO−ion reacts by various pathways, such as proton transfer,SN2 substitution,E2 elimination and attack on the carbonyl group. The CH3S−ion is unreactive towards CF3COC6H5but is able to react by hydride transfer,SN2,E2 and/or carbonyl attack with the remaining neutral species. The CH2S−radical anion reacts by electron transfer to afford stable molecular radical anions of CF3COCF3and CF3COC6H5, whereas the main reaction with the two esters, CF3CO2CH3and CF3CO2C2H5, is dissociative electron transfer leading to CF3CO2−and CF3−ions. The CH2C(CH3)CH2−anion displays a more complex reactivity pattern involving electron transfer,SN2,E2 as well as attack on the carbonyl group. Direct evidence for the occurrence of electron transfer as the initial step in an overallBAC2 type process has not been obtained for the systems studied. The reaction of the CH2S−ion with CF3CO2C6H5was observed, however, to yield exclusively a CF3COCHS−. radical anion. Based upon the absence of aBAC2 process in the reaction of CH2S−with the methyl and ethyl esters of trifluoroacetic acid in combination with the facile occurrence of electron transfer from this radical anion, it is suggested that the CF3COCHS−. ion is formed by an initial electron transfer followed by coupling between the CH2S molecule and the CF3CO2C6H5−radical anion and subsequen

ISSN:0165-0513    

DOI:10.1002/recl.19961150304

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractTheMorinring expansion of penicillin 1‐oxides to cephalosporins has been extended to norpenicillin 1‐oxides. To this end, both the norpenicillin sulfoxide moiety and the methyl group should be β‐oriented. Norpenicillin 1‐oxides are prepared from properly protected exomethylene penam derivatives using hydrogen on palladium/carbon and oxidation with 3‐chloroperoxybenzoic acid or peroxya

ISSN:0165-0513    

DOI:10.1002/recl.19961150305

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractFour potentially tridentate bis(2‐pyridylalkyl)amines, differing in the number of methylene groups in the alkyl chain, have been coupled to the epoxy‐containing bifunctional spacer (3‐glycidoxypropyl)trimethoxysilane (GLYMO) and subsequently grafted onto silica. These ion exchangers were characterized by solid‐state CP‐MAS13C‐NMR and elemental analyses. The obtained ligand concentrations varied from 0.29‐0.63 mmol/g ion exchanger. With the only exception of Alfa‐GLYMO‐bis(2‐pyridyl)amine, which showed a very low capacity for any of the metal ions tested, these ion‐exchange materials selectively absorbed Cu2+, with a maximum capacity of 0.22‐0.59 mmol/g ion exchanger at pH 5.6, from aqueous solutions containing a mixture of the divalent metal ions Cu2+, Ni2+, Co2+, Cd2+and Zn2+. The metal‐uptake capacities and distribution coefficients established at different pH, correlate with the length of the alkyl bridge in the chelating ligand. The longer the alkyl spacer the lower the capacity and the metal‐ligand complex stability at lower pH. The use of strong chelating tridentate N‐donor ligands greatly increases the ligand occupation by metal ions. The Cu2+uptake varies strongly with pH in the case of Alfa‐GLYM

ISSN:0165-0513    

DOI:10.1002/recl.19961150306

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150307

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150309

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150310

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150301

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY