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41.
42.
Bruce A. Carlson Jean-Jacques Katz Herbert C. Brown 《Journal of organometallic chemistry》1974,67(2):C39-C42
Treatment of hindered borinic esters, R2 BOR′; with an equimolar quantity of α,α-dichloromethyl methyl ether and lithium triethylcarboxide yields the α-chloroboronic esters, R2 CHClB(OCH3)OR′, in excellent yields. In cases where the steric requirements of R are not sufficient, the steric requirements of R′ can be increased to achieve the synthesis. 相似文献
43.
Summary A simple, sensitive, accurate and reliable method for morphine determination in biological samples has been developed. It uses reverse-phase HPLC on a polymeric column with an eluent (0.05 mol/L dibasic sodium phosphate: acetonitrile, 8515) at pH 9.5, allowing both the suppression of ionization of morphine amine and the promotion of oxidation of the phenolic group. Amperometric detection at mild oxidizing potential (350 mV) proves very selective, and, therefore, only a simple and rapid one-step liquid-liquid sample preparation is required. Under these conditions clean chromatograms are obtained even with complex biological matrices such as cadaveric blood, urine and hair.Minimum detectable amount of morphine is about 200 pg injected. A calibration line with a correlation coefficient of 0.99996 has been produced over the range 7.5–250 ng/mL. Precision results comparable to other HPLC methods.A preliminary report was presented at the 25th T.I.A.F.T. Meeting 1988, Groningen (NL), June 27–30 1988. 相似文献
44.
45.
Michel Dedieu Yves-Louis Pascal Pierre Dizabo Jean-Jacques Basselier 《Journal of mass spectrometry : JMS》1977,12(3):153-158
The mass spectra of the title compounds always show an intense molecular ion. Some fissions involve loss of the ethylenic group, while others are related to cleavage of the dithiane ring, eventually followed by recyclizations involving the ethylenic chain stabilized by the resonance possibilities. If a phenyl group is present in the ethylenic chain, the spectra are modified by the formation of the very stable benzothiopyrylium ion. 相似文献
46.
47.
Odile Convert Catherine Deville Jean-Jacques Godfroid 《Magnetic resonance in chemistry : MRC》1977,10(1):220-223
The 13C n.m.r. spectrum of the bridge substituted dicoumarols are interpreted in order to obtain structural information for quantitative structure-activity relationships. The results are in agreement with those obtained by 1H n.m.r. These dicoumarols exhibit double restricted rotation around both bridge bonds. 相似文献
48.
In this study, a method was developed for determination of steroid hormones (17beta-estradiol, estrone, 17alpha-ethynylestradiol) in tap and sewage water samples from Sweden. Sample preparation and analysis were performed by a hollow-fibre microporous membrane liquid-liquid extraction (HF-MMLLE) set-up combined with gas chromatography-mass spectrometry (GC-MS). In this approach, only the organic liquid in the lumen (10microL) of the hollow-fibre membrane was utilised for depleting extraction. Several parameters were studied, including: type of organic solvent, sample pH, salt and humic acid content. The optimised method allowed the determination of the analyte at the low ngL(-1) level in tap and sewage water. A linear plot gave correlation coefficients better than 0.995 and resulted in a method limit of detection of 1.6, 3 and 10ngL(-1) for 17beta-estradiol, estrone, and 17alpha-ethynylestradiol, respectively, in sewage water. Enrichment factors were over 1400 after derivatisation. The repeatabilities at 50 and 600ngL(-1) were better than 10% and 6%, respectively. 相似文献
49.
50.
Jean-Jacques Vasseur Bernard Rayner Jean-Louis Imbach 《Journal of heterocyclic chemistry》1988,25(2):389-392
We have elucidated the exact mechanism of apurinic oligodeoxynucleotide d(Tp[AP]pT) cleavage by phenylhydrazine and shown that the final isolated product is in fact a 3-substituted derivative of 1-phenyl-pyrazole. 相似文献