Glycol esters, preparation

Propylene Glycol Esters. These emulsifiers are formed by an alcoholysis reaction of propylene glycol and fatty acids, and are predominantly used in cakes, prepared mixes, whipped toppings, and breads (36). 

Commercial lecithin is insoluble but infinitely dispersible in water. Treatment with water dissolves small amounts of its decomposition products and adsorbed or coacervated substances, eg, carbohydrates and salts, especially in the presence of ethanol. However, a small percentage of water dissolves or disperses in melted lecithin to form an imbibition. Lecithin forms imbibitions or absorbates with other solvents, eg, alcohols, glycols, esters, ketones, ethers, solutions of almost any organic and inorganic substance, and acetone. It is remarkable that the classic precipitant for phosphoHpids, eg, acetone, dissolves in melted lecithin readily to form a thin, uniform imbibition. Imbibition often is used to bring a reactant in intimate contact with lecithin in the preparation of lecithin derivatives. 

MetlylEsters. The addition product of two moles of TYZOR TPT and one mole of ethylene glycol, GLY—TI, can be used as a transesterification catalyst for the preparation of methyl esters. The low solubility of tetramethyl titanate has prevented the use of them as a catalyst for methyl ester preparation (488). 

Preparation of Ethylene Glycol Esters from Synthesis Gas... 

Chung, Y. and H. Cho. 2004. Preparation of highly water soluble tacrolimus derivatives poly(ethylene glycol) esters as potential prodruofteh. Pharm. Re 7 878-883. 

Figure 3 shows the results of sin investigation of the pH-sensitivity of a crosslinked poly(ortho ester) prepared from 3,9-bis(ethylidene 2,4,8,10-tetraoxaspiro [5,5] undecane), triethylene glycol, and 1,2,6-hexanetriol. In these studies, a marker molecule, p-nitroacetanilide was incorporated into the polymer, and the rate of release of p-nitroacetanilide was assumed to correspond to the rate of erosion of the polymer. This assumption is not entirely accurate because some diffusional release occurs. However, the method is a good measure for determining the changes in erosion rates with changes in external pH. 

Figure 3 Effect of external pH on erosion rate of crosslinked poly(ortho ester) prepared from 3,9-bis(ethylidene 2,4,8,10-tetraoxaspiro [5,5] undecane), triethylene glycol, and 1,2,6-hexanetriol. Disks 5.5 x 0.75 mm p-nitroacetanilide loading 2 wt. ...

Chiral [160, l70, l80]phosphomonoesters and ATPy[l60, l70, lsO] have been synthesized by Knowles and associates, who devised the procedure outlined in Fig. 19 [51-55], The procedure has been used to synthesize phenyl[160, l70, l80]phos-phate and 2-[160,170,180]phospho-D-glycerate as well as the propylene glycol ester shown. The starting cyclic adduct was prepared by reaction of (— )-ephedrine with P17OCl3, giving a separable mixture of 2-chloro-l,3,2-oxazaphospholidin-2-ones whose chemistry had been described [56], The major isomer was converted to (/ p)-l-[160, nO,180]phospho-1,2-propanediol and (Sp)-ATPy[l60, nO, lsO] by the reactions shown. The stereochemistry at each step of the synthesis was well prece-dented in the literature nevertheless, the configurations were verified by independent methods described in the next section. 

T. Nakata et al. developed a simple and efficient synthetic approach to prepare (+)-methyl-7-benzoylpederate, a key intermediate toward the synthesis of mycalamides. The key steps were the Evans asymmetric aldol reaction, stereoselective Claisen condensation and the Takai-Nozaki olefination. The diastereoselective Claisen condensation took place between a 5-lactone and the lithium enolate of a glycolate ester. 

Figure 9. Condensation of ethyl chloroacetate and phosphorus esters. Preparation of phosphorus esters of ethyl glycol ate. (25, 26, 27, 28>...

Tosylation of the glycol to prepare the ditosylate ester starting material is most often done using pyridine as the solvent and base (Bailey et al., 1978 Dale and Kristiansen, 1972 Kyba et al., 1977), The method is not complicated, but the ditosylate product sometimes is a liquid, especially when polyethylene glycol was used, and must be purified by column chromatography. 

The chelation-controllcd rearrangement of O-protected glycolic esters 1 results in high product diastereoselectivity (for the preparative procedure cf. p 3421)4SS. 

A second method of base-catalyzed thiannulation is illustrated in Scheme 8. The reaction proper involves a l-chloro-2-formylalkene (such as 215 normally prepared from 214 by the Vilsmeier-Haack reaction) and thio-glycolic ester (216). Ester 217 (75% from 215) was hydrolyzed to the carboxylic acid (74%) and decarboxylated to the parent tetracycle (39) (87%).75 Other... 

Jiratumnukul, N. M.R. Van De Mark. Preparation of glycol esters of soybean oil fatty acids and their potential as coalescent aids in paint formulations./. Am. Oil Chem. Soc. 2000, 77, 691-697. 

Note that the terminal groups on the polymers prepared in reactions 1 and 2 are free hydroxyls. Thus, if a diisocyanate is reacted with a mixture of these two polymers the adipic acid-propylene glycol ester polymer may be linked to the polyethylene glycol. The final polymer contains blocks of ester and polyglycol joined by a urethane linkage and is known as a block polymer. It is interesting to note that only a small amount of isocyanate is required since the number of free hydroxyls is very few. 

Carbonylation of cw, ra j-perhydro-9b-boraphenalene (3b) in the presence of (CH20H)2 results in the formation of essentially a single product identified as an ethylene glycol ester of the boronic acid (56) (90%). Oxidation of this ester produces c ,c ,tranj-perhydro-9b-phenalenol (55) (70%) <67JA5478, 83OS(61)i03>. a//-tra j-Perhydrophenalene (58) was prepared via dehydration-hydrogenation of (55) via mixed alkenes (57) (Scheme 20). 

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