Sucrose carboxylic acid ester

Once bearing some substituents, the decrease of polarity of the sucrose derivatives makes them soluble in less-polar solvents, such as acetone or tert-butanol, in which some lipases are able to catalyze esterifications. Unlike proteases, which necessitate most often the use of an activated acyl donor (such as vinyl or trifluoroethyl esters), lipases are active with simple esters and even the parent carboxylic acids in the presence of a water scavenger. The selectivity of the lipase-catalyzed second esterification is specific for OH-6 allowing the synthesis of mixed T,6 -diesters.123,124 For some lipases, a chain-length dependence on the regiochemistry was observed.125 Selectively substituted monoesters were thus prepared and studied for their solution and thermotropic behavior.126,127 Combinations of enzyme-mediated and purely chemical esterifications led to a series of specifically substituted sucrose fatty acid diesters with variations in the chain length, the level of saturation, and the position on the sugar backbone. This allowed the impact of structural variations on thermotropic properties to be demonstrated (compare Section III.l).128... 

In the early researches on 0. europaea, [35], Panizzi demonstrated that oleuropeic acid 31, the 4-( 1. hydroxyisopropyl> 1 -cycloexene-1 -carboxylic acid, occurs in the root bark of (). europaea, mainly as a sucrose ester, i.e. the 6-O-oleuropeil saccharose 32 (see Figure 14). The structure of 31 was determined by comparison with an authentic sample [36-38]. The demonstration of the position of ester linkage in oleuropeil saccharose 32 was achieved with a combination of enzymatic and chemical reactions [39]. 

V sol in eth, methanol and nitrobenz si sol in benz V si sol in ethanol insol in petr eth. Prepn is by nitration with a mixt of nitric and sulfuric acids at 0° in the presence of a mixt of other compds consisting mainly of an alkyl ester of a hydroxy aliphatic carboxylic acid, the alkyl group of which contains not more than five C atoms (such as nitrated ethyl or butyl lactate) together with amyl nitrate and dichloro-ethyl ether. The octanitrate is crystd at about 80°. Recrystn is from methanol (Refs 2 thru 7) Sucrose Octanitrate is extremely sensitive to heat and friction (Ref 9). It has an expln temp of (puffs off at) 167—70° a Rf 1289.3kcal/mole ... 

Figure. 1. Nature of glandular trichome-mediated aphid resistance in 5. berthaultiL Key (1) Carboxylic acid sucrose esters (CASE), (2) Viscous type B trichome exudate, (3) Increased aphid movement and attempts to escape, (4) Adhesive aphid tarsi, (5) Enhanced rupture of type A trichome membrane , (6) Polyphenoloxidase + 02 + substrate, (7) Aphid alarm pheromone, E-(B)=famesene, (8) Encasement of tarsi by trichome exudate, (9) Greater effective tarsal size, (10) Decreased aphid mobility, (11) Occlusion of mouthparts by trichome exudate, (12) Starvation and death. Adapted from (38).

Type B trichome exudate of S. berthaultii also conditions abnormal behaviors in aphids and leafhoppers, particularly delay in host acceptance as measured by an increase in time to the first probe and a decrease in feeding time (Table I) (21.22V The avoidance/deterrance responses of aphids are conditioned by the presence of sucrose esters of short-chain branched carboxylic acids in the type B exudate (Table ID (23.24). Sensory receptors on the tarsi and/or antennae of aphids are the likely target sites of sucrose esters in type B exudate (24). 

Olestra is a zero-calorie commercial fat substitute with the look and feel of natural fats. It Is a synthetic compound whose structure involves a novel combination of natural components. The core of olestra Is derived from sucrose, ordinary table sugar. Six to eight of the hydroxyl groups on the sucrose framework have long-chain carboxylic acids (fatty acids) appended to them by ester linkages. These fatty acids are from Cs to C22 in length. In the industrial synthesis of olestra, these fatty acids derive from... 

NON-CALORIC FAT SUBSTITUTE AND NEW TYPE EMULSIFIERS ON THE BASIS OF SUCROSE ESTERS OF CARBOXYLIC ACIDS... 

Successful reduction of fat consumption requires both qualified fat substitutes and effective emulsifiers. Esters of sucrose and fatty acids can act either as non-caloric fats / 1 / or as surfactants / 2 / depending on the number of bound fatty acids. The objectives of this investigation were to synthesize a non- or low-caloric fat substitute as well as emulsifiers on the basis of sucrose esters of carboxylic acids in a solvent-free synthesis procedure suitable for human nutrition. 

As might be expected, the search for an even better artificial sweetener continues. Alitame is a dipeptide formed from aspartic acid and alanine, with an unusual amide at the carboxylate end of the alanine. It is 2000 times as sweet as sucrose— 1 pound of alitame has the sweetening power of I ton of sucrose In addition, because an amide bond is more stable than an ester bond, alitame is more stable to hydrolysis than is aspartame. Therefore, alitame keeps its sweetness in aqueous solution better than aspar-... 

In many cases, the extent of reaction (from acid value determination) was 85-90%. However, in some cases as low as 70% conversion of carboxyl groups was noted, e.g. in the reaction using a sucrose pentadehy-drated castor ester containing potassium soaps (but no tertiary amine), tetrahydrophthalic anhydride and bisphenol A diglycidyl ether with no substantial reduction in acid value after a few hours further heating. 

Synthesis from sucrose ester/half-ester derivatives, monoepoxide and diisocyanate. Sucrose "penta"-soyate (the methanol insoluble fraction of the soap-free product) was reacted at 100°C for 4 hours with a mixture in xylene of 1 mole equivalent cyclic anhydride e.g., phthalic or tetrahydrophthalic anhydride and monoepoxide e.g., styrene oxide or Cardura E (the glycidyl ester of versatic acid), branched C9-Cfatty acids, in the presence of N-benzyl dimethylamine as catalyst. A faster rate was achieved with the phthalic system. The course of reaction between half ester carboxyl groups and epoxide groups was followed by acid value. About 90% reaction was achieved in all cases and to the product was added 1.0 mole toluene diisocyanate (the meucimum amount without gelation) and dibutyl tin dilaurate as catalyst. 

One of the most widely used artificial sweeteners available today is a dipeptide, consisting of a unit of aspartic acid linked to a unit of phenylalanine. The carboxyl group of the phenylalanine moiety has been converted to the methyl ester. This substance is known commercially as aspartame, but it is also sold under the trade names NutraSweet and Equal. Aspartame is about 200 times sweeter than sucrose. It is found in diet soft drinks, puddings, juices, and many other foods. Unfortunately, aspartame is not stable when heated, so it is not suitable as an ingredient in cooking. Other dipeptides that have structures similar to that of aspartame are many thousands of times sweeter than sucrose. 

The solvent also plays an important role in the success of the reaction. In general, reaction in benzene or toluene gives higher yields of inverted products. - Although pyridine is not suitable in the preparation of nucleotides, pyridine can be used for the synthesis of sucrose epoxide, and a mixture of dioxane-pyridine (9 1) can be utilized in the preparation of sugar carboxylates. Mixed solvent systems may be necessary when the acid and alcohol components have widely differing solubilities. Thus a mixture of HMPA and dichloromethane works well in the synthesis of lipophilic carbohydrate esters such as cord factor. ... 

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