Ketones, fractionation

Separate the ketone layer from the water, and redistil the lattCT rmtil about one third of the material has passed over. Remove the ketone after salting out any dissolved ketone with potassium carbonate (5). Wash the combined ketone fractions four times with one third the volume of 35-40 per cent, calcium chloride solution in order to remove the alcohol. Dry over 15 g. of anhydrous calcium chloride it is best to shake in a separatory funnel with 1-2 g. of the anhydrous calcium chloride, remove the saturated solution of calcium chloride as formed, and then allow to stand over 10 g. of calcium chloride in a dry flask. Filter and distil. Collect the methyl n-butyl ketone at 126-128°. The yield is 71 g. 

The data in Table 7 show that the selectivity for 2-oxygenated products in the oxidation of alkanes on TS-1 is somewhat higher than could be expected on statistical grounds. Only for 3-methylpentane, this selectivity becomes overcompensated by the higher reactivity of tertiary C-H compared to secondary C-H positions. This indicates that the first step of the oxidation, i.e. the formation of alcohols from alkanes is slightly regioselective. Within the ketone fraction, the selectivity for 2-ketones is even more pronounced, indicating that 2-alcohols are selectively oxidized to 2-ketones in the... 

In the distillate the ketone layer is separated from the water, and the latter is distilled until one-third has been collected. The ketone layer in this distillate is separated, and the water layer is again distilled. This procedure is repeated as long as any considerable amount of ketone is obtained in the distillate (Note 3). The combined ketone fraction is washed four times with one-third its volume of a concentrated solution of calcium chloride (sp. gr. 1.3 or greater) to remove alcohol (Note 4), then dried over 50 g. of solid calcium chloride, filtered and distilled. The yield of methyl M-amyl ketone boiling at 148-151° at 750 mm. is 300-350 g. (52-61 per cent of the theoretical amount, based upon the original ethyl acetoacetate) (Note 5). 

Fig. 6. Regioselectivity in the ketone fraction expressed as standarized molar ratios of C2/C3 and C2/(C4+C5). Corrections are made so as to have an equal number of C2 and (C4 + C5) positions in the n-alkane chain, irrespective of its chain length. Conditions are the same as in Fig. 4.

Central to investigations of the biosynthetic pathway and regulation of the contact pheromone of B. germanica was the observation that the major cuticular hydrocarbon in all life stages of this species is an isomeric mixture of 3,7-, 3,9-and 3,11-dimethylnonacosane (Jurenka el al., 1989). The presence of only the 3,11-isomer in the cuticular dimethyl ketone fraction and only in adult females prompted Jurenka et al. (1989) to suggest that production of the pheromone might result from the female-specific oxidation of its hydrocarbon analog. This scheme follows the well-established conversion of hydrocarbons to methyl ketone and epoxide pheromones in the housefly (Blomquist et al., 1984 Ahmad et al., 1987). 

The oil is separated (Note 3), and the aqueous layer is extracted with two 50-cc. portions of benzene. The extracts are combined with the oil, and the solvent is distilled off. Fractionation of the residue imder reduced pressure gives 80-95 g. of a methyl benzyl ketone fraction, boiling at 110-120°/21-22 mm., and a residue of dibenzyl ketone (Note 4). The main fraction on redistillation yields 74-87 g. (55-65 per cent of the theoretical amoimt) of methyl benzyl ketone boiling at iio-ii5°/2i-22 mm. (Notes 5, 6, and 7). 

Indeed, the XH-NMR spectrum of the ethyl methyl ketone fraction of the product after PerAcr polymerization confirmed this assumption by featuring two doublets at 5.57 and 5.82 ppm, indicating the formation of the alkene-terminated PvDMTPD chain ends. 

In a typical preparative scale experiment adamantane (1 gram) was oxidized with a CCbF solution of ozone at —78°C. for 8 days. After working up by the usual method, the residue was dissolved in ether and washed with aqueous sodium hydroxide. The ether layer on evaporation yielded a white crystalline solid (870 mg.). Elution with light petroleum (b.p., 30-40°C.) from neutral alumina (175 grams) gave unchanged adamantane (505 mg.), and 30% diethyl ether in petroleum eluted a ketonic fraction (63 mg.). Finally, pure ether eluted 1-adamantanol (227 mg.). TLC of the ketonic fraction separated the major component—adamantanone— from a minor unidentified component. 

After carbonate removal using 6N HCl the samples were extracted with chloroform and methanol (1 1) (Fig. 1 Simoneit et al., 1981). Extract concentrates were separated by TLC on silica gel after esterification of the carboxylic acids (Fig. 1). Fractions corresponding to hydrocarbons, carboxylic acid esters, ketones and polar compounds were isolated for instrumental analysis (Simoneit et al., 1981). The amounts of material in the hydrocarbon, ester, and ketone fractions from the TLC separations were determined by weighing replicate aliquots of a few microliters each on a Cahn microbalance and, after averaging, calculating the yields. 

A procedure for the separation of ketonic from nonketonic steroids was devised by Girard (56) and depends upon the formation of water-soluble betaine hydrazones of the ketosteroids from which the nonketonic material is readily separable by extraction. The ketosteroids may then be liberated by add hydrol3rsis and recovered by extraction with ether. Analyses may be p ormed by either the colorimetric or polar< raphic method on the purified ketonic fraction. The application of this procedure to urinary extracts for analytical purposes was introduced by Talbot (118) and subsequently modified by Talbot (119), Pincus (102), and Dobriner et ai. (38). Engstrom and Mason (47) have shown that identical values are obtained by the Callow method for the ketonic fraction and the corrected total neutral fraction. If the Holtorff-Koch method is used, however, the values on the total neutral fraction are somewhat higher, as was pointed out above. The values obtained by this method on the ketonic fraction are in good agreement with those obtained by the Callow modification. 

Poly(ferf-bUtyl vinyl ketone) Fractional precipitation heptane ( J / 1) Acetone/meth ol Solvent volatilization, 150°C, 1140... 

---