Esters sulfate monoesters

The synthesis of sulfosuccinate esters—either monoesters or diesters—or the corresponding amides is usually done in a two-step procedure. In both cases, the MA is reacted in the first step with organic alcohol, organic amine, or (in the case of monoesters) with other suitable organic reactants that bear hydroxyl (or even protic) groups in the second step sulfation of the maleic ester takes place. 

Sulfate monoesters can react by dissociative paths, and this is the favored path. Whether such reactions are concerted or involve a very short-lived sulfur trioxide intermediate has been the subject of debate. ° Benkovic and Benkovic reported evidence suggesting that the nucleophile is present (though there is little bond formation) in the transition state for the reaction of amines with p-nitrophenyl sulfate. Alkyl esters of sulfuric or sulfonic acids normally react with C-0 cleavage only when this is disfavored, as in aryl esters, does one see S-0 cleavage. Sulfate diester... 

The hydrolysis of sulfate monoesters has been studied increasingly in relation to sulfate group transfer in vivo. In general, the rate-enhancing effect on the sulfate cleavage is small even with hydroxamate- or imidazole-functionalized cationic micelles which are extremely effective for the hydrolysis of phenyl esters. Recently, Kunitake and Sakamoto (1979a) found that zwitterionic hydroxamate [47] cleaved 2,4-dinitrophenyl sulfate effectively in cationic and... 

A different approach to the synthesis of sulfate esters was discussed by Buncel and co-workers (97 ). The sulfate monoester was obtained after neutral or alkaline methanolysis of methyl 4-nltro-phenyl sulfate. The methoxide Ion attacks only at the alkyl carbon with the formation of dimethyl ether and 4-nltrophenyl sulfate Ion as the leaving group. Other substituted methyl phenyl sulfates have been converted to phenyl sulfates In the same manner (98). Correspondingly l,2 5,6-dl-0-lsopropylldlne-a-D-glucofuranose was reacted with phenyl chlorosulfate to give the carbohydrate... 

Phosphoric and sulfuric acid derivatives possess crucial properties that allow them to uniquely fill their many roles in biochemistry. Phosphoric acid may be esterified to form a monoester, diester, or triester (Figure 1). Sulfuric acid may be esterified at one or two positions, to form a monoester or a diester. Sulfate diesters are highly reactive, and have not been found in nature nor do phosphate triesters occur naturally. The hydrolysis of both phosphate and sulfate esters are thermodynamically favorable, but nucleophiles are repelled by the negative charge of the ionized forms. The resulting kinetic stability of phosphate monoesters and diesters, and of sulfate monoesters, is a major factor in their suitability for biological roles. For example, the half-life for hydrolysis of alkyl phosphate dianions by water is approximately 1.1 X 10 years k=2 x 10 s ) at 25°C. Such species... 

Figure 1 On the left are the structures of a phosphate monoester, diester, and triester. The first pK of an alkyl phosphate monoester, and the pKa of a dialkyl diester, are typically between 1 and 2. The second pKa of an alkyl monoester is approximately 6.8, and from one to two units lower for aryl esters. At the right are the structures of a sulfate monoester and diester. Sulfate monoesters have a very low pKa values and as a result are always ionized at physiological pH.

Sulphur was found through spark source mass spectrometry to be abundant in SRS-A [93], Also, incorporation of S into SRS has been reported [64,94-96], The observation that several thiols enhance SRS formation in different systems [97-100] and that arylsulfatase (an enzyme that cleaves sulfate monoesters of phenolic and other unsaturated hydroxylated systems) inactivates SRS-A [101,102] opened the view that a thiol is a constituent of the active compound. However, it has recently been shown that the SRS-inactivating action of commercially available arylsulfatase is not due to sulfate ester cleavage, but to a dipeptidase contaminant [103,104]. The destruction of different SRS compounds by hpoxygenase [67,105,106] shows that SRS contains a cij,c/s-1,4-pentadiene structure, since this is a prerequisite for a lipoxygenase substrate [107], For a review of the earlier structural work on SRS, see ref. 108. 

Other sulfated esters of polyols have been suggested as surfactants and have, in fact, been extensively patented. Sulfated monoesters of ethylene glycol and pen-taerythritol have received some attention in that regard. They have not, in general, found much commercial acceptance, probably because of the hydrolytic instability of the ester linkage. 

These are two chemically different groups of products which have distinct application fields. Both product groups are obtained by reacting maleic acid anhydride (MA) with hydroxyl group(s)-carrying molecules, followed by sulfation of the intermediate product, an ester. Whereas the diester types are mainly made from a few different branched and unbranched alcohols, the monoester are derived from a wide variety of raw materials fatty alcohols, fatty acid alkanolamides, ethoxylated fatty alcohols, fatty acid alkanolamides, their etho-xylates, and others. All these raw materials—with the exception of the branched chains—may be obtained from natural renewable resources. 

Cellulose Sulfates and Phosphates. Conversion of cellulose to sulfate or phosphate monoesters produces soluble derivatives. These ester groups are highly hydrated, offer steric interference to molecular fit, and are ionized at all PH levels so they continually produce coulombic repulsion. 

Figure 20 Possible mechanisms for sulfate ester hydrolysis catalyzed by members of the AS family. Formation of the sulfoenzyme (a) nucleophilic attack of the hydrated FGly oxygen on the substrate (b) nucleophilic attack of the sulfate oxygen of the substrate on the aldehyde FGly yields a diester sulfoenzyme, which hydrolyzes into the sulfoenzyme monoester. Enzyme desulfurylation (c) elimination of inorganic sulfate leaves an aldehyde moiety, which is hydrated to give a gerr7-diol (d) nucleophilic attack of a nucleophile, such as water, yields the hydrated gerr7-diol FGly.

Ammonium, (coconut oil alkyl) trimethyl-, methyl sulfate. See Cocotrimonium methosulfate Ammonium coco-sulfate CAS 90989-98-3 EINECS/ELINCS 292-758-6 Synonyms Coconut oil, sulfate, ammonium salt Sulfuric acid, coco alkyl monoester, ammonium salt Sulfuric acid, monococoyl ester, ammonium salt Classification Organic compd. 

Sulfuric acid, coco alkyl monoester, ammonium salt. See Ammonium coco-sulfate Sulfuric acid, cocoyl ester, magnesium salt. 

Alkyl sulfates as monoesters of the dibasic sulfuric acid have only one hydrophobic group in the molecule, while in the case of the tribasic sulfosuccinic acid, both monoesters and diesters can be formed. This gives a broader variation and influence of the surface-active properties. In general, it can be said that sulfosuccinates containing less than eight to ten carbons atoms in each ester group exhibit a sufficient solubility in water. 

We have seen the formation of sulfonate esters from sulfinic acids. Sulfuric acid (A) can form esters as well—either the monoesters (B) or the diester (C), which is known as a dialkyl sulfate. Esters of phosphoric acid (D) play a prominent role in biology. The phosphate linkages in nucleotides (see Chapter 28, Section 28.5) are important. Using D as a template, draw the mono- and diesters of phosphoric acid using cyclopentanol as the alcohol component. Take each of the phosphate esters you have drawn and draw the product you will obtain when they are treated with a base such as sodium hydride (NaH). 

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