Esters sulfates

Glucuronidation. Complexation of the steroid to glucuronic acid, most predominantiy via the C-3 hydroxyl, leads to a considerable portion of the excreted metabohtes of ah. glucocorticoids. In infants, sulfurylation (formation of a sulfate ester) is also predominant (16). 

The hydroxyl groups on glycols undergo the usual alcohol chemistry giving a wide variety of possible derivatives. Hydroxyls can be converted to aldehydes, alkyl hahdes, amides, amines, a2ides, carboxyUc acids, ethers, mercaptans, nitrate esters, nitriles, nitrite esters, organic esters, peroxides, phosphate esters, and sulfate esters (6,7). 

Detoxifica.tlon. Detoxification systems in the human body often involve reactions that utilize sulfur-containing compounds. For example, reactions in which sulfate esters of potentially toxic compounds are formed, rendering these less toxic or nontoxic, are common as are acetylation reactions involving acetyl—SCoA (45). Another important compound is. Vadenosylmethionine [29908-03-0] (SAM), the active form of methionine. SAM acts as a methylating agent, eg, in detoxification reactions such as the methylation of pyridine derivatives, and in the formation of choline (qv), creatine [60-27-5] carnitine [461-06-3] and epinephrine [329-65-7] (50). 

THE can be polymerized by many strongly acidic catalysts, but not all of them produce the requked bitimctional polyether glycol with a minimum of by-products. Several large-scale commercial polymerization processes are based on fluorosulfonic acid, HESO, catalysis, which meets all these requkements. The catalyst is added to THE at low temperatures and an exothermic polymerization occurs readily. The polymerization products are poly(tetramethylene ether) chains with sulfate ester groups (8). 

Mercaptothiazolines ate obtained from the corresponding sulfate esters and carbon disulfide,... 

Indirect Hydration. Indirect hydration is based on a two-step reaction of propylene and sulfuric acid. In the first step, mixed sulfate esters, primarily isopropyl hydrogen sulfate, but also diisopropyl sulfate, form. These are then hydrolyzed, forming the alcohol and sulfuric acid. 

By-Products. Diisopiopyl ethei is the piincipal by-pioduct formed by reaction of the intermediate sulfate esters with isopropyl alcohol. 

Other by-products include acetone, carbonaceous material, and polymers of propylene. Minor contaminants arise from impurities in the feed. Ethylene and butylenes can form traces of ethyl alcohol and 2-butanol. Small amounts of / -propyl alcohol carried through into the refined isopropyl alcohol can originate from cyclopropane [75-19-4] in the propylene feed. Acetone, an oxidation product, also forms from thermal decomposition of the intermediate sulfate esters, eg. 

Process. A typical indirect hydration process is presented in Eigure 1. In the process, propylene reacts with sulfuric acid (>60 wt%) in agitated reactors or absorbers at moderate (0.7—2.8 MPa (100—400 psig)) pressure. The isopropyl sulfate esters form and are maintained in the Hquid state at 20—80°C. Low propylene concentrations, ie, 50 wt %, can be tolerated, but concentrations of 65 wt % or higher are preferred to achieve high alcohol yields. Because the reaction is exothermic, internal cooling coils or external heat exchangers are used to control the temperature. 

The sulfate ester hydrolysate is stripped to give a mixture of isopropyl alcohol, isopropyl ether, and water overhead, and dilute sulfuric acid bottoms. The overhead is neutralized using sodium hydroxide and refined in a two-column distillation system. Diisopropyl ether is taken overhead in the first, ie, ether, column. This stream is generally recycled to the reactors to produce additional isopropyl alcohol by the following equiUbrium reaction ... 

Sulfated Natural Oils and Fats. Sulfated natural triglycerides were the first nonsoap commercial surfactants introduced in the middle of the nineteenth century. Since then sulfates of many vegetable, animal, and fish oils have been investigated (see also Fats AND FATTY oils). With its hydroxyl group and a double bond, ricinoleic acid (12-hydroxy-9,10-octadecenoic acid) is an oil constituent particularly suited for sulfation. Its sulfate is known as turkey-red oil. Oleic acid is also suited for sulfation. Esters of these acids can be sulfated with a minimum of hydrolysis of the glyceride group. Polyunsaturated acids, with several double bonds, lead to dark-colored sulfation products. The reaction with sulfuric acid proceeds through either the hydroxyl or the double bond. The sulfuric acid half ester thus formed is neutralized with caustic soda ... 

Butanol is produced commercially by the indirect hydration of / -butenes. However, current trends are towards the employment of inexpensive Raffinate 11 type feedstocks, ie, C-4 refinery streams containing predominandy / -butenes and saturated C-4s after removal of butadiene and isobutylene. In the traditional indirect hydration process, / -butenes are esterified with Hquid sulfuric acid and the intermediate butyl sulfate esters hydroly2ed. DEA Mineraloel (formerly Deutsche Texaco) currentiy operates a 2-butanol plant employing a direct hydration of / -butenes route (18) with their own proprietary catalyst. 

Hydrolysis. The primary functions of hydrolysis are to remove some of the acetyl groups from the cellulose triester and to reduce or remove the combined acid sulfate ester to improve the thermal stabiUty of the acetate. 

The ester is washed thoroughly in iron-free water to remove acid and any desirable salts these wash Hquids are sent for acid recovery. The final wash may contain some sodium, calcium, or magnesium ions to stabilize traces of sulfate esters remaining on the cellulose acetate. 

The Wenker aziridine synthesis entails the treatment of a P-amino alcohol 1 with sulfuric acid to give P-aminoethyl sulfate ester 2 which is subsequently treated with base to afford aziridine 3. Before the discovery of the Mitsunobu reaction, wbicb transforms an amino alcohol into an aziridine in one step under very mild conditions, the Wenker reaction was one of the most convenient methods for aziridine synthesis. However, due to the involvement of strong acid and then strong base, its utility has been limited to substrates without labile functionalities. 

In 1935, Wenker" first prepared P-aminoethyl sulfate ester (4, a solid) from thermal dehydration of monoethanolamine acid sulfate at 250°C according to Gabriel s procedure." Subsequently, the mixture of 4 and 40% NaOH aqueous solution was distilled. Further fractional distillation of the distillate in the presence of KOH and then Na at 55-56 C led to pure aziridine in 26.5% yield. 

The mechanism for the Wenker aziridine synthesis is very straightforward. As depicted by conversion 2—>3, the transformation is a simple case of intramolecular Sn2 displacement process, in which the sulfate ester is the leaving group. 

Due to the convenience of the Wenker aziridine formation from P-aminoethyl sulfate ester (4) and base, many improvements ensued. Leighton et al. improved the yield of the first step for the formation of sulfate ester 4. First of all, both ethanolamine and 95% sulfuric acid were diluted with half of their weight of water and then slowly mixed together at 0 C. Finally, by keeping the temperature below 145 C, sulfate ester 4 was obtained in 90-95% yield. 

Mesylates and tosylates may be used as variants of the 0-sulfate ester. For instance, 55% of aziridine 7 was obtained from base-mediated cyclization of amino mesylate 6. In comparison, the classic Wenker protocol only gave 3% of 7. In another instance, A-tosyl amino alcohol 8 was tosylated to give 9, which was transformed to aziridine 10 in 64% yield, along with 29% of the P-elimination product due to the presence of the ester moiety. Likewise, aziridine 12 was assembled from tosylate 11 in two steps and 60% yield. ... 

As described in Section 1.7.1, the utility of the Wenker reaction is limited to substrates without labile functionalities because of the involvement of strong acid and then strong base. The Fanta group prepared a variety of aziridines by taking advantage of the Wenker reaction.For example, 6-aza-bicyclo[3.1.0]hexane (14) was produced from the ring-closure of ( )-rra s-2-aminocyclopentanol hydrochloride (13). In a similar fashion, sulfate ester 16 was prepared from A-methyl dl-trans- >-ssmnoA-hydroxytetrahydrofuran (15). Subsequent treatment of sulfate ester 16 with NaOH then delivered aziridine I . " Additional examples of Wenker aziridine synthesis may also be found in references 15-17. 

Due to the abundance of epoxides, they are ideal precursors for the preparation of P-amino alcohols. In one case, ring-opening of 2-methyl-oxirane (18) with methylamine resulted in l-methylamino-propan-2-ol (19), which was transformed to 1,2-dimethyl-aziridine (20) in 30-35% yield using the Wenker protocol. Interestingly, l-amino-3-buten-2-ol sulfate ester (23) was prepared from l-amino-3-buten-2-ol (22, a product of ammonia ring-opening of vinyl epoxide 21) and chlorosulfonic acid. Treatment of sulfate ester 23 with NaOH then led to aziridine 24. ... 

The influence of other groups in a pyridine or similar ring system is more difficult to assess because no kinetic data are available. The deactivating effect of the bromine atom in the 2-position is greater than that in the 3-position, while 2,6-dibromopyridine is very slow to react with dimethyl sulfate. Esters, amides, and nitriles of nicotinic and isonicotinic acids undergo fairly easy quaternization at about... 

Chemical Name 4,4 -(2-pyridinylmethylene)bisphenol bis(hydrogen sulfate) (ester) disodium salt... 

A) A solution of (SMI (320 mg) in trifluoroacetic acid (7 ml) was kept under nitrogen at room temperature for 15 minutes. Ether (100 ml) was added and the precipitate filtered, washed thoroughly with ether and dried. This material (280 mg) was added to concentrated sulfuric acid (20 ml), cooled at -20°C. The solution was kept in the dry ice-acetone bath at -20°C for 75 minutes. The sulfuric acid solution was poured into ice water (80 ml). The precipitate was centrifuged, resuspended in ice water (30 ml) and 4N sodium hydroxide was added until a clear solution was obtained. After reacidification to pH 4 with dilute sulfuric acid, the precipitate formed was centrifuged, washed twice with ice water and dried. Yield 155 mg. Chromatograph of DEAE Sephadex (with ammonium carbonate buffer) yielded the desired octa-peptide sulfate ester 30 mg. 

The important observation from the data in Table 3 is that NC samples subjected to acid bod followed by tetrahydrofuran (THF)-benzene treatment yielded essentially the same sulfate contents as samples subjected to THF-benzene treatment alone. From this the authors interpret that sulfate contents from THF-benzene treatments actually represent absolute values of the difficult-to-remove sulfate which may very well be true sulfate ester . It is also tentatively concluded that approximately 90% of the original sulfate content in unstabilized NC is readily removable sulfuric acid with the remainder the more difficult-to-remove sulfate ester. Dilute acid boil treatment of NC for 56 hours does not eliminate all of the free sulfuric acid and leaves the difficult-to-remove sulfate practically unchanged... 

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