Polyhydroxy esters

Dusek, K. and Matejka, L., Transesterification and Gelation of Polyhydroxy Esters Formed from Diepoxides and Dicarboxylic Acids, in Rubber Modified Thermoset Resins, Riew, C. K. and Gillham, J. K. (Eds), Am. Chem. Soc., Adv. Chem. Series 208 (l984), pp. 15-26. 

Synthetic polyhydroxy esters have been subjected to GC in the form of the trimethylsilyl ethers [988], as trifluoroacetates [988] and as isopropylidene derivatives [985], Erythro- and fhreo-forms of vicinal diols can be separated on packed columns when they are converted to either of the last two derivatives and, as these compounds can be prepared quantitatively to a high degree of stereochemical purity from cis- or frans-olefins respectively, this provides a basis for gas chromatographic separation and estimation of stereoisomers of unsaturated acids on packed columns [985]. (Epoxide derivatives can be used in a similar manner as discussed in Sections D.1 and 2 above [116,243,244], it appears to be a general rule that derivatives with the trans- or threo-... 

TABLE 11 TLC Analysis of Polyhydroxy Esters and Their Ethoxylates... 

The melting points of these esters are usually much lower than those of the corresponding 3 5 dinitrobenzoates their preparation, therefore, offers no advantages over the latter except for alcohols of high molecular weight and for polyhydroxy compounds. The reagent is, however, cheaper than 3 5 dinitrobenzoyl chloride it hydrolyses in the air so that it should either be stored under light petroleum or be prepared from the acid, when required, by the thionyl chloride or phosphorus pentachloride method. 

Composition. Shellac is primarily a mixture of aUphatic polyhydroxy acids in the form of lactones and esters. It has an acid number of ca 70, a saponification number of ca 230, a hydroxyl number of ca 260, and an iodine number of ca 15. Its average molecular weight is ca 1000. Shellac is a complex mixture, but some of its constituents have been identified. Aleuritic acid, an optically inactive 9,10,16-trihydroxypalmitic acid, has been isolated by saponification. Related carboxyflc acids such as 16-hydroxy- and 9,10-dihydroxypalmitic acids, also have been identified after saponification. These acids may not be primary products of hydrolysis, but may have been produced by the treatment. Studies show that shellac contains carboxyflc acids with long methylene chains, unsaturated esters, probably an aliphatic aldehyde, a saturated aliphatic ester, a primary alcohol, and isolated or unconjugated double bonds. 

Possible uses for these polyhydroxy compounds include the preparation of alkyd-type resins with polybasic acids, the formation of ester plasticizers, and the preparation of surface-active agents. 

Reaction of polyhydroxy compounds with polybasic acids gives rise to condensation polymers containing ester (—COO—) groups. Because of the presence of these groups such polycondensates are known as polyesters and find use in such diverse applications as fibres, surface coatings, plasticisers, rubbers and laminating resins. These materials are discussed in detail in Chapter 25. 

By reaction of polyhydroxy compounds with a carbonic acid derivative, a series of related polymers may be produced with carbonate (—0 C0 0—) linkages, the polymers being referred to as polycarbonates. Carbonic acid, C0(0H)2, itself does not exist in the free state but by means of ester exchange Figure 20.1) (1) and phosgenation techniques (II) it is possible to produce useful products. 

Unless the hydroxyl groups have such proximity that cyclisation takes place, polycarbonates will normally be produced whenever phosgene or a carbonate ester is reacted with a polyhydroxy compound. This means that a very large range of polycarbonate resins are possible and in fact many hundreds have been prepared. 

The choice of the alcohol permits manipulation of the structure of the polymer. Water and monohydric alcohols afford linear chains with carboxylic acid and ester end groups, respectively. Polyhydroxy initiators afford a route to ester end-blocked star and comb polymers (Fig. 4) (47). 

Figure 17-14. Formation of complexes of boric acid with glycerol. Three hydroxyl units form an ester and one unit forms a complex bond. Here a proton will be released that lowers the pH. The scheme is valid also for polyhydroxy compounds. In this case, two polymer chains are connected via such a link.

The carbon-chain structure of the sugar obtained from hamameli-tannin was established by the classical method of Kiliani,26 which is based on the reduction, with hydrogen iodide, of polyhydroxy acids to fatty acids. Treatment of the calcium salt of hamamelonic acid under these conditions led to inconclusive results. The reduction of the corresponding, crystalline ammonium salt, however, furnished 3.5 to 5% of 2-methylvaleric acid, which was identified by the properties of its crystalline p-iodophenacyl ester. Thus, it was proved that the sugar must have structure XIV. 

Some areas where ortho esters have found use involve the elucidation of the structure proof of polyhydroxy alkaloids [4-8], the protection of the esterified hydroxyl groups during chemical transformations of the other parts of the molecule [9], the area of pharmacological screening [10], and the preparation of novel polymers [11]. 

H.F. Bluhm, USP 3256214(1966) CA 65, 9132(1966) [Prepn of explosive polyurethane resins, which are suitable for use as sensitive coatings for AN blasting compns and for prepn of foamed resin expls is described. The resins, which can be cured at RT, are prepd by reaction of an org poiyiso-cyanate with a nitric acid partial ester of a polyhydroxy compd including a component contg > OH groups reactive with the isocyanate. For example, equal parts by wt of an-hydroenneaheptitol nitrate (13.77 wt %N as... 

Likewise, unprotected polyhydroxy compounds can be successfully fluorinated to give the products resulting from substitution of the hydroxy groups by fluorine, wn-o-lnositol reacts with sulfur tetrafluoride and anhydrous hydrogen fluoride at ambient temperature to give a moderate yield of the cyclic sulfite ester of tw/o. cfo-5,6-difluoro-7-oxabicyclo[2.2.1 heptane-e.w,e.vo-2,3-diol (6) and, alter hydrolysis, the free difluoro diol 7.61... 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

Acids Esters polyhydroxy compounds oximes. and some aryl-alkyl hydrocarbons. hydrocarbons. ketones. Nitriles. 

Polyhydroxy- phenols. amino acids, di- and polyamino compounds, amino alcohols. Sulphonic acids. Sulphinic acids. Salts. sulphinic acids, aminosulphonic acids and sulphonamides. Some diketones and /3-keto esters. Ethers and acetals. Lactones. Acyl halides. Diaryl ethers. intermediate reduction products of nitro compounds. Sulphones, sulphonamides of secondary amines, sulphides, sulphates and other sulphur compounds. 

In addition to stereochemical influences, polar effects might be important in determining the initial site of oxidative attack on certain derivatives of polyhydric alcohols. Muller and Varga68 found that the polyhydroxy furoic ester derivative (XIV) gave the 2-C -formyl derivative (XV) in about 80 %... 

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