摘要:

AbstractThe title compound, a masked 3,6‐di‐n‐propyl‐o‐benzoquinone, was synthesized from 3,6‐di‐n‐propylcatechol in 82% yield. Its Diels‐Alder reactions with methyl propiolate, phenylacetylene, 1‐octyne, dimethyl acetylenedicarboxylate, diphenylacetylene and 3‐hexyne were studied. The yields of the adducts were excellent except for the last two cases in which the unimolecular decomposition of the title compound to generate 3,6‐di‐n‐propylcatechol methylene ether predominates. The regiochemistry of the adducts derived from monosubstituted acetylenes were determined by the correlation of13C chemical shifts of the adducts and the corresponding bicyclo[2.2.2]octa‐5,7‐diene‐2,3‐diones obtained from the hydrolysis of the spirolactone ring of the Diels‐Alder adducts. Photolysis of these α‐diketones gave the corresponding aromatic compounds in high yields. These synthetic sequences provide an effective entry to bicyclo[2.2.2]octa‐5,7‐diene‐2,3

ISSN:0009-4536    

DOI:10.1002/jccs.198300011

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe decomposition rate of the chemically activated ethylmethylether produced from dimethyl ether‐oxygen‐diazomethane photolysis at 3660Å have been measured to be 2∼5×106sec−1. By comparing the pressure dependent variation of rate constants with the RRKM calculation results, the strong collision behavior of dimethylether and the gaussian energy distribution of singlet methylene are d

ISSN:0009-4536    

DOI:10.1002/jccs.198300012

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe membrane material was prepared by mixing 40% of cesium‐triphenyl‐cyanoborate and 60% of PVC powder. The mixture was pressed at a pressure of 20tons/cm2for 1hoursto make the membrane. Then, the membrane was mounted on a self‐constructed electrode body. Nernstian slope of 60mv/decade was obtained throughout the concentration range 10−1∼2×10−5M. Selectivity coefficients were presented. The life time of the electrode is longer

ISSN:0009-4536    

DOI:10.1002/jccs.198300013

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractAmorphous zirconium phosphate ion‐exchanger has been prepared in our laboratory according to the procedure given by Gal and Gal. The Chemical composition has been determined. Some chemical properties; stabilities and sorption of mono‐ to hexavalent cations have been studied in detail. It was found that washing the zirconium phosphate ion exchanger with alcohol before drying would increase the exchange capacity of amorphous zirconium phosph

ISSN:0009-4536    

DOI:10.1002/jccs.198300014

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractMaleic acid (MA) in aqueous sulfuric acid undergoes catalytic isomerization in the presence of small amounts of Cerium(IV) ion andN‐bromosuccinimide (NBS) orN‐bromoacetamide (NBA). The rate of isomerization is very fast even at room temperature and the yield is quite acceptable. The rate of isomerization depends on the relative amounts of MA, Ce(IV), NBS, NBA, and H2SO4. However, maleic acid has greater effect on the final yield. Sulfuric acid exhibits more chemical effect than physical effects. The competitive redox reactions of Ce(IV), NBS, and NBA with MA limit the yield of isomerization to about 85%. In the vicinity of room temperature, a raise of five degrees in temperature nearly doubles the rate of isomerization. Acrylamide shows inhibitive effect on the isomerization. The rate of hydrolysis of NBS or NBA in aqueous acidic solution depends on the concentrations of hydrogen ion, and NBS or NBA itself. The rate of hydrolysis of NBA is much faster than that of NBS. Mechanism involving bromine atom as catalyst is proposed to explain experimental resu

ISSN:0009-4536    

DOI:10.1002/jccs.198300015

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractA procedure utilizing NMR spectrometry in the quantitative analysis of clove oil is described. The1H‐NMR spectrum is determined with acetophenone as internal standard, the13C‐NMR spectrum is determined with chloroform as internal standard and 0.1MCr(acac)3as relaxation reagent. The contents of eugenol are compared to the results obtained from G.C. (90.8%, s.d. 0.7%) and from chemical method (89.6% s.d. 1.2%).The result obtained from1H‐NMR method is 90.4% (s.d. 0.3%) and from13C‐NMR method is 90.5% (s.d. 0.7%). The time required for the1H‐NMR method is about 20minsand for the13C‐NMR method is about 2‐3hours. Apparently the1H‐NMR method proves to be more simple, rap

ISSN:0009-4536    

DOI:10.1002/jccs.198300016

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractA gas chromatographic method was established for the quantitative analysis of pipemidic acid. The method is based on alkylation of pipemidic acid with diazomethane catalyzed by boron trifluoride. The sample was chromatographed on a stainless steel column packed with 5% OV‐101 on Chromosorb G‐HP andn‐octacosane was used as an internal standard. Quantitation is achieved by measuring peak‐height ratio. The method was satisfactorily applied to the analysis of pipemidic acid in

ISSN:0009-4536    

DOI:10.1002/jccs.198300017

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractMost of the reaction achieved in this work were conducted with coumarin and furocoumarin. The reactions were performed on inert thin‐layer chromatoplates under controlled conditions and the products of the reactions were compared as usual with the expected substances on the same chromatogram. The reactions performed were: mineral acid hydrolysis, methylation, acetylation, benzoylation, nitration and Schiff's bases on silica gel chromatoplate

ISSN:0009-4536    

DOI:10.1002/jccs.198300018

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

ISSN:0009-4536    

DOI:10.1002/jccs.198300019

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

ISSN:0009-4536    

DOI:10.1002/jccs.198300020

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY