Ketone-carboxylic acid fraction

Ketone / Carboxylic Acid fraction, of the lipid composition of a Pliocene... 

Spectra of fulvic acids must be interpreted carefully purification of this fraction leads to losses that can reach 50%. Comparison of spectra of different humic fractions of the same sample, such as a sediment from the Oman Sea (Fig. 6) illustrates several differences. Oxygenated functional groups are more important in fulvic and humic acids than in stable residues. Particularly important are the absorption bands at 3400 cm (OH from alcohols, acids, etc.), 1710 cm (C==0 from quinones, ketones, carboxylic acids), 1250 cm (C—O from alcohols, esters, ethers) and 1050 cm (C—O from carbohydrates). Absorption at 1050 cm is nearly absent in stable residues. Aliphatic content increases from fulvic acids to humic acids and stable residues (bands between 2870 and 2960 cm ) and the shape of the aliphatic bands (2900-2950 1450 1375) indicates that fulvic acids contain mainly CH groups. 

Many esters occur naturally Those of low molecular weight are fairly volatile and many have pleasing odors Esters often form a significant fraction of the fragrant oil of fruits and flowers The aroma of oranges for example contains 30 different esters along with 10 carboxylic acids 34 alcohols 34 aldehydes and ketones and 36 hydrocarbons... 

The ring closure of L-cysteine by reaction with aldehydes or ketals 190 194 involving Schiff s base intermediates 195 leads to (4R)-thiazolidine-4-carboxylic acids. Except for formaldehyde and symmetrical ketones, the condensation of L-cysteine with aldehydes or unsymmetrical ketones generates a mixture of epimers, i.e. (25,4R)- and (2R,4R)-thiazolidine-4-carboxylic acid derivatives that can be separated by RP-HPLC or fractional crystallization. 139 ... 

The results of the infrared analysis are presented in Table VI. These results show that carboxylic acids and phenols are found only in the acid concentrates. Carboxylic acids are concentrated in the polar acid subfractions III and IV while phenols are concentrated in subfraction II. Carbazoles, ketones, and amides are found in all three major nonhydrocarbon fractions. The appearance of the same compound type in several fractions may arise from differences in acidity or basicity that are caused by the hydrocarbon portion of the molecule. Multifunctionality could also be a factor in the distribution of compound types among the fractions. The 1695 cm"1 band was assigned to ketones on the basis of work... 

Aliphatic EC5-EC8 Fraction. Examination of urinary metabolites in humans and rats after exposure to /7-hexane indicates that hydrocarbons in this fraction may be oxidatively metabolized via cytochrome P-450 oxidases to several alcohol, ketone, and carboxylic acid derivatives. Based on... 

The above principles of the method are indicative of its great potential and flexibility (see, e.g., Beroza [141] and Tumlinson and Heath [142]). Rcker and Sievers [146,147] proposed to apply selective complexation by a europium(lll) coordination polymer sorbent for the pre-fractionation of volatile compounds (e.g., ketones, aldehydes, alcohols and carboxylic acids). 

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. 

The most common accelerators for methyl ethyl ketone peroxide and cyclohexanone peroxide are salts of metals which exhibit more than one valency. The most widely used metal of this kind is cobalt, although salts of cerium, iron, manganese, tin and vanadium also find some application. In order to be effective as an accelerator a metal salt must be soluble in the polyester resin. The most commonly used salts are naphthenates, which are readily soluble octoates also may be used. (Naphthenic add is extracted from the gas oil and kerosene fractions of petroleum and consists of a complex mixture of carboxylic acids of substituted cyclopentanes and cyclohexanes. ) The decomposition of a hydroperoxide (ROOH) by a metal salt such as cobalt naphthenate to give free radicals proceeds according to the following chain reaction ... 

B. Ethyl pyrrole-2-carboxylate. In a 1-1. three-necked round-bottomed flask equipped with a sealed mechanical stirrer and powder funnel are place 1.0 g. of sodium and 300 ml. of anhydrous ethanol. When the sodium is dissolved, 75 g. (0.35 mole) of pyrrol-2-yl trichloromethyl ketone from Part A is added portionwise over a 10-minute period (Note 4). After the addition is complete, the solution is stirred 30 minutes, then concentrated to dryness using a rotary evaporator. The oily residue is partitioned between 200 ml. of ether and 25 ml. of 3 N hydrochloric acid. The ether layer is separated, and the aqueous layer is washed once with 100 ml. of ether. The ether solutions are combined, washed once with 25 ml. of saturated sodium bicarbonate solution, dried with magnesium sulfate, and concentrated by distillation. The residue is fractionated at reduced pressure to give 44.0-44.5 g. (91-92%) of ethyl pyrrole-2 carboxylate as a pale yellow oil, b.p. 125-128° (25 mm.) (Note 5). The yield based on pyrrole is 70-74%. Upon standing at room temperature the product crystallizes, m.p. 40-42°. 

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