Four organic-modified clays based on a SWy-2 montmorillonite were prepared by embedding ammonium organic derivatives with different chelating functionalities (NH2, COOH, SH or CS2) in the interlayer space of montmorillonite. Organic molecules such as (a) hexamethylenediamine, (b) 2-(dimethylamino)ethenethiol, (c) 5-aminovaleric acid and (d) hexamethylenediamine-dithiocarbamate were used for the clay modification in order to study the effect of the chelating functionality on heavy metal ions binding from aqueous solutions. The organoclays were characterized by powder X-ray diffraction (XRD), infrared (FTIR) and NMR spectroscopies. The experimental data showed that the organic molecules are intercalated into the interlamelar space with the long dimension parallel to the clay sheets. Their sorbing properties were evaluated for the removal of heavy metals, Pb, Cd and Zn, from aqueous solutions as a function of the pH. When compared with the unmodified SWy-2 montmorillonite, the modified clays show significant improvement in terms of sorbing selectivity as well as of metal loading capacity. The fit to adsorption data by a Surface Complexation Model shows that the intercalated molecules act as specific binding sites in the clay. These contribute additional sorption capacity which is additive to the variable charge edge-sites of the clay in competition with the permanent charge sites.

Peroxidation of lipids produces low-molecular-weight carbonyl compounds, which are reactive with biological nucleophiles. The analysis of these compounds is often difficult. A multicomponent method for the determination of 11 of them in biological samples is reported. The samples are subjected to a pretreatment-derivatization procedure followed by gas chromatographic analysis with either electron-capture detection (ECD) or mass-selective detection (MSD) in the selected-ion monitoring mode. The procedure involves derivatization of the analyte with 2,4,6-trichlorophenylhydrazine, extraction with n-hexane, and separation of the derivatization products on a nonpolar gas chromatographic column. The concentration of the derivatization reagent, pH, reaction time, temperature, and presence of extraneous ions were investigated to determine the optimal derivatization conditions. Under these conditions, the method allows for the selective detection of low-molecular-weight carbonyl compounds at femtomole levels in several biological materials such as plasma, urine, and bovine serum albumin without interferences. The limits of detection were in the ranges 0.01–0.2 μM for ECD and 0.15–1.5 μM for MSD. The mean procedural recoveries obtained during the method validation were within the range 85–95% and the intra- and interassay standard deviations do not exceed 4.6 and 6.1%, respectively.

3-Trichloromethylnitrobenzene 2, 1,3-dinitro-5-trichloromethylbenzene 13 and 3-trichloromethylbenzonitrile 18 react with sodium methoxide to give 4-methoxy-3-nitrobenzaldehyde 6, 4-methoxy-3,5-dinitrobenzaldehyde 15 and 5-dimethoxymethyl-2-methoxybenzonitrile 19, respectively. Compounds 2 and 13 react with methyl thioglycolate to afford dichloromethylacetates 7 and 16, respectively. These products are the result of tele nucleophilic aromatic substitution. Compound 18 reacted with methyl thioglycolate to give acetate 20 resulting from nucleophilic displacement of cyanide. Reductive cyclisation of 7 afforded benzothiazine 11.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The scope of abnormal reactions of nucleophiles with beta-trichloromethylazines is further explored: reactions of 3-trichloromethylpyridine with nucleophiles other than methoxide, and reactions of 3-trichloromethylpyridine N-oxide and 3,5-bis(trichloromethyl)pyridine with methoxide. Attack at ;a ring carbon, followed by hydrogen migration to the side-chain, occurred in most cases, though attack at the trichloromethyl carbon was also sometimes observed.

Opening the bladder via the perineum in order to remove a bladder stone was practised by the ancient Greek surgeons in very early times, probably from the days of Homer. The technique of lithotomy was described for the first time by Celsus in the first century AD and has come to be known as the lesser operation or 'apparatus parvus', so called because only to instruments are needed for it, a knife and a hook. Two fingers of the surgeon's left hand were introduced into the patient's rectum while an assistant pressed on the lower abdomen to encourage descent of the stone near the neck of the bladder. A slightly curved incision was made in the skin near the anus and a second transverse incision was made through or immediately above the prostate, opening the bladder neck. The calculus was extracted from the wound by the fingers or by a hook. This ancient method of lithotomy as described by Celsus was the only one performed until the middle of the 16th century, and many surgeons advised the apparatus parvus as the operation of choice in young patients until the middle of the 18th century.