The seed oil of Melia (Azadirachta) indica has been critically re‐examined particularly with reference to fatty acid composition, using the gas chromatograph as a means of analytical control.
Behenic acid has been discovered as a component and the presence of myristic acid and lignoceric acid verified. The limitations of some earlier methods of analysis are illustrated. A suitably purified neem oil has been successfully reduced to the corresponding saturated and unsaturated alcohols by a selective sodium reduction procedure of potential industrial value.
The reduction products and their acetyl esters have been examined by gas‐liquid chromatography. A comparison is made between the results obtained from methyl esters as derivatives and those obtained from the alcohols and their acetates.
Lane, Uxbridg e, M idd lesexThe Friedel-Crafts acetylation and benzoylation of iodobenzene and the isomeric iodotoluenes have been investigated in a range of solvents and a t a range of temperatures. Under specific conditions good yields of p-iodoacetophenone or p-iodobenzophenone may be obtained. The reactivities of the iodotoluenes follow the sequence p -< o-< rn-. The main products formed in the acylation of o-iodotoluene are 3-iodo-4-methyl-and 4-iodo-3methyl-acetophenones (or -benzophenones). rn-lodotoluene generally affords acetophenones or benzophenones in the order 4-iodo-2-methyl-> 2-iodo-4-methyl-> 2-iodo-6-methyl. In acylations p-iodotoluene gives very-(3-1 1 %) or benzophenone (2-36%) proceeds essentially by this path. However, the molar ratios of di-iodobenzene to aceto-(or benzo-)phenone are near unity, as '
Recently the isomer distribution in the bromination of substrate (Ia) was investigated: the isomers formed were (Ib) (98-2%), (IIb) (1.00%), (IIIb) (0.51%), and (IVb) (0.27%). I n the presence of sunlight chlorination of substrate (Ia) gave the l-isomer (Ic).~ Nitration of hydrocarbon (Ia) is more complex, as many early studies . SOC., 1968, 90, 906. internal standard; the signals were singlets, unless one of the following abbreviations is used: br = broad, d = doublet, dd = doublet of doublets, m = multiplet, c = complex.Gus Chromatography .-Analyses were performed using a glass column 5 f t x in (i. diam.) packed with Bentone 34 (3.5%) and Carbowax 20M (1.5%) on Celite (80-100 mesh) (treated with hexamethyldisilazane) . Nitrogen was used as carrier gas, a t 177", together with a Pye 104 instrument, fitted with a flame ionisation detector. Peak areas were measured by triangulation. The identity of the peaks were also checked using other chromatographic columns. Mass response of the detector towards different ketones was determined, and corrections applied as appropriate. KovAts 52 retention indices ( I ) are given in Table 4, which also gives the slopes (b) of the plots of log (retention volume) vs. the carbon number for the n-alkane. (Ib) .-This compound was obtained 2 C as an oil (yield 75%), b.p. 128-130" a t 3 mmHg 61 M.
l-Bromo-2-methylnaphthalene
A stripping technique has been used to cencentrate selected hydrocarbons present in water samples at the parts per billion level for analysis by gas chromatography. The chromatograms of hydrocarbons thus stripped from several different water samples show similarities. Washing out of atmospheric pollutants by rainfall is postulated as an explanation of these results. This hypothesis is supported by a comparison of the data with those for trace atmospheric analysis. The comparison shows that the same compounds are present in similar relative amounts both in water samples and the atmosphere. After a period of rain the atmospheric concentrations decrease whilst the water bound concentrations increase.
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