Product compn. of polyglycerol esters, prepd. from a direct alk. polymn. of glycerol followed by esterification with stearic or oleic acids, was studied. The internal product compn., as analyzed by high performance liq. chromatog. (HPLC), shows clearly that in contradiction to what has been published recently, the fatty acid radicals are not distributed at random among all available hydroxyl groups, and thus, any theor. calcn. on the product compn. could not be correct. The product compn. of the crude material indicates clearly that the internal positions (secondary hydroxyls) of the glycerol polymer are esterified with greater difficulty than the primary hydroxyl groups. [on SciFinder(R)]

A nonconventional method for the evaluation of emulsion stability was developed. The method was valid for viscous emulsions. The technique is based on elec. cond. measurements during nondestructive short-cooling-heating cycles carried out on cosmetic viscous emulsions. Cond. curves were obtained on a recorder, where the second heating cycles were lower and almost parallel to the first heating curves. The bigger the cond. differences between the two heating curves, the lower was the emulsion stability. A relative Stability Index $Δ$/h, indicating relative change in cond. between 2 cycles was elaborated. This index was useful for detg. optimal required hydrophile-lipophile balance values for required emulsions, optimal amt. of oily phase and emulsifier concn. [on SciFinder(R)]

The less thermodynamically stable modification of tristearin [555-43-1], termed $\alpha$, is preserved when 1-10% of sorbitan monostearate [1338-41-6] emulsifier was added before allowing the molten fat to cool and crystallize. Several other emulsifiers were tested, and it was found that the combination of bulkiness of the hydrophilic groups and the appropriate length of the hydrophobic chains of a given emulsifier is necessary to preserve the $\alpha$-modification. Liq. emulsifiers and those having a pronounced hydrophilic character are not efficient as modifiers. The emulsifier was incorporated into the tristearin during crystn. from solvent without an immediate effect, but it affects subsequent behavior upon melting and resolidification. [on SciFinder(R)]

The oxidn. of oleic acid and the cleavage of the carbon-carbon bond was achieved using potassium permanganate added to oil in water emulsion. The best emulsifier for the oxidn. and cleavage of the double bond was polyoxyethylene lauryl ether (HLB 16.9) which formed the best emulsion with the smaller droplets. The oxidn. is controlled by parameters affecting emulsion stability. Increasing the concns. of emulsifier or oxidizing agent improves the oleic acid conversion and azelaic acid formation. Poor stirring, low HLB's, high oil phase content and poor emulsion prepn. decrease the yields. [on SciFinder(R)]

Stearic acid can exit in 3 main crystal structure modifications. The crystal structure is detd. by solute-solvent interactions. When changes occur in the growth conditions, for instance in flow regime or by increased cooling rate, the crystal modification is affected. Addn. of small amts. of surfactants will force the stearic acid to crystallize in only one modification regardless of the crystn. and the nature of the solvent. [on SciFinder(R)]

Fatty acid esters of glycerol or tetraglycerol are prepd. by the transesterification of Me esters of fatty acids (esp. Me stearate [112-61-8]) with glycerol or tetraglycerol at 95-150° in the presence of an alk. catalyst and an anionic or nonionic emulsifier. These esters are not highly substituted. Emulsion formation and the catalyst are required for high transesterification yields. The effects of temp., type and concn. of emulsifier, and reactant ratio on the transesterification were examd. [on SciFinder(R)]

DTA anal. was used to confirm evidence from x-ray diffraction studies for the existence of 1:1 mixed sitosterol-cholesterol crystals. The curve of m.p. against compn. has an inflection point at about 1:1 ratio. The DTA peaks for 1:1 mech. mixts. and for 1:1 mixed crystals are different with respect to symmetry and width. The curve of the heat of enthalpy against the compn. of crystals also changes indicating a change in entropy. This can be attributed to the difference between melting mixed crystals (high order) and solid soln. (low order). The soly. curve in the sitosterol-cholesterol-alc. system has also a region of inflection confirming the previous conclusion. [on SciFinder(R)]

Calcium ion concentration versus time was measured in solutions containing admixture of 10 per cent tested urine of normals and stone-formers, during induced calcium oxalate precipitation. A Discriminating Index was formulated by statistical analysis of the data. It was found that stone-formers and normals differ significantly with respect to the measurements and the Discriminating Indices. An equation to evaluate the odds of stone-forming based on results of an individual test has been derived. The Discrimination Index may be recommended as a diagnostic tool.[on SciFinder (R)]

A new interpretation is suggested for the results obtained from a simultaneous thermogravimetry(TG)-DTA measurement of oil in water (o/w) emulsions. The endothermic DTA peak obtained at the phase inversion temp. of the emulsion is due to a sudden change in the rate of water evapn. and not to any internal thermal change of the system. [on SciFinder(R)]

The correlation between the crystal habit and the compn. of cholesterol crystals formed in 4 org. solvents (MeOH, MeCN, EtOH, and acetone) was studied. Anhyd. and monohydrate cholesterol were pptd. in anhyd. and aq. org. solvent mixts., resp. The appearance of plates does not automatically guarantee the presence of hydrated cholesterol, and the presence of 5% or more of water in the crystn. solvent may not result in the formation of monohydrate cholesterol. [on SciFinder(R)]

The optimum results in the 2-step industrial prepn. of polyglycerol [25618-55-7] esters of fatty acids are obtained with a polymn. temp. of 260-280° in an inert gas with 2.5 mol% NaOH as the catalyst, followed by esterification at ≥230° without addnl. catalyst. A simulation model of a chem. plant is used to det. the cost of prodn. of the emulsifiers. [on SciFinder(R)]

The effect of various org. solvents and crystn. conditions on the crystal habit of anhyd. cholesterol was studied. Both plates and needle-like crystals can be obtained in a particular solvent depending on the degree of supersatn. of the soln. However, the crystals grown at about the same supersatn., from different solvents, show differences in their habit indicating dependence on the solvent-solute interaction. Thus, it is advisable not to identify needle-like crystals with anhyd.-cholesterol and plates with monohydrate cholesterol without specifying the crystn. conditions. A prediction on the crystal habit length to width ratios can be made using these parameters. [on SciFinder(R)]

1,4-Di-tert-butylbenzene (DTBB) was crystd. from several org. solvents to study the effect of solvents and crystn. conditions on its habit. The length to width ratio of DTBB crystals varies from 1.2 to 20 being correlated directly to the max. attainable supersatn. Some effect of elongation was detected caused by addn. of impurities to the crystg. soln. A special crystal habit modification of acicular outgrowths was noted in crystals grown from tert-butyl-alc. The appearance of outgrowths is ascribed to solvent-solute alignment induced by structural compatibility of the DTBB mol. and tert-butyl-alc. dimers. [on SciFinder(R)]