Ether sulfates hydrolysis

As esters of sulfuric acid, the hydrophilic group of alcohol sulfates and alcohol ether sulfates is the sulfate ion, which is linked to the hydrophobic tail through a C-O-S bond. This bond gives the molecule a relative instability as this linkage is prone to hydrolysis in acidic media. This establishes a basic difference from other key anionic surfactants such as alkyl and alkylbenzene-sulfonates, which have a C-S bond, completely stable in all normal conditions of use. The chemical structure of these sulfate molecules partially limits their conditions of use and their application areas but nevertheless they are found undoubtedly in the widest range of application types among anionic surfactants. 

FIG. 1 Kinetics of the hydrolysis of sodium hexyl sulfate and several alcohol ether sulfates. 1, Sodium hexyl ether (1 PrO) sulfate, K = 0.0075 min1 2, sodium octyl ether (1 PrO) sulfate, AT, - 0.0071 min 1 3, sodium octyl ether (1 EO) sulfate, AT, = 0.0051 min1 and 4, sodium hexyl sulfate, AT, = 0.0037 min1. 

Sanchez et al. [61,62] studied the stability of sodium decyl, dodecyl, and tetradecyl sulfates and sodium lauryl ether (3 EO) sulfate in acid media (pH 1) at different temperatures and concentrations above and below the critical micelle concentration. Sodium decyl sulfate was shown to be relatively stable for several hours at temperatures up to 90°C. Sodium dodecyl and tetradecyl sulfates were only stable for short periods of time at temperatures above 40-50°C. As expected, sodium lauryl ether sulfate was less stable to hydrolysis than the corresponding lauryl sulfate. 

The alkyl chain distribution of the base alcohol in alcohol sulfates is easily determined by gas chromatography. However, alcohol sulfates and alcohol ether sulfates are not volatile and require a previous hydrolysis to yield the free alcohol. The extracted free alcohol can be injected directly [306] or converted to its trimethylsilyl derivative before injection [307]. Alternatively, the alcohol sulfate can be decomposed by hydroiodic acid to yield the alkyl iodides of the starting alcohols [308]. A preferred method forms the alkyl iodides after hydrolysis of the alcohol sulfate which are analyzed after further extraction of the free alcohol, thus avoiding the formation of hydrogen sulfide. This latter method is commonly used to determine the alkyl chain distribution of alcohol ether sulfates. 

Alcohols react with nascent hydroiodic acid to form alkyl iodides. When the starting material is an alcohol ether sulfate, the resulting alcohol ethoxylate obtained by acid hydrolysis of the sulfate gives the corresponding alkyl iodides. The number of moles of diiodoethane equals the number of moles of ethylene oxide present in the alcohol ethoxylate. Diiodoethane decomposes or reacts with more hydrogen iodide to give iodine quantitatively in both cases. However,... 

Alcohol and alcohol ether sulfates are commonly considered as extremely rapid in primary biodegradation. The ester linkage in the molecule of these substances, prone to chemical hydrolysis in acid media, was considered the main reason for the rapid degradation. The hydrolysis of linear primary alcohol sulfates by bacterial enzymes is very easy and has been demonstrated in vitro. Since the direct consequence of this hydrolysis is the loss of surfactant properties, the primary biodegradation, determined by the methylene blue active substance analysis (MBAS), appears to be very rapid. However, the biodegradation of alcohol sulfates cannot be explained by this theory alone as it was proven by Hammerton in 1955 that other alcohol sulfates were highly resistant [386,387]. 

Ether sulfates are sensitive to hydrolysis in acid solution and because an acid salt is formed by hydrolysis, the reaction would then become autocatalytic. Therefore, commercially available ether sulfates are usually buffered. Such products contain concentrations of ether sulfates of < 30%, or 65-70%. In the region between these concentrations, ether sulfates form very rigid gels. 

The hydrophilic component of these molecules is a carboxylic group, as is the case in the soap molecule. In general, an aceto- or propiocarboxylic group is attached to the polyoxyethylene chain by an ether bond. The free alkylcarboxylic acids can be prepared from salts such as fatty acid soaps. In contrast to alkyl ether sulfates, alkyl ether carboxylates contain no ester bonds and therefore they are not susceptible to hydrolysis. 

The methods for estimation of ethereal sulfate are based upon hydrolysis of the ester and precipitation of the resultant inorganic sulfate either as barium or benzidine sulfate. Many modifications of these methods are described in the literature. Other methods, e. g., the rhodizonic acid (73) method, are usually unsuitable owing to interference by urinary constituents. In all methods it is necessary to distinguish between inoi anic and ethereal sulfate, the usual procedure being to estimate inorganic sulfate before and after hydrolysis, it being assumed that the difference is all due to ethereal sulfate. 

Description. Alkyl ether sulfates (AES), which are also called alcohol ethoxy sulfates (AEOS), result from the sulfation of an ethoxylated alcohol. As will be mentioned in a later section covering the ethoxylated alcohols, there is usually, and more especially in industrial-grade raw materials, a rather broad distribution in the ethoxylation degree. The ether sulfates are stable under alkaline conditions but are rapidly hydrolyzed under acidic conditions and even under neutral conditions this hydrolysis is ascribed to an autocatalytic acidification process that progressively takes place and continues growing. 

E sulfonates d alcools gras ethoxyl s Because fatty alcohol ether sulfates are sensitive to - hydrolysis it is attractive to use f., where the sulfur is directly linked to the carbon. There are several possibilities for synthesis but none of them gained large-scale importance. 

Surfactants are used in miscellar flooding to form a microemulsion of the residual oil. They must have high stability against hydrolysis. - Sulfonates and (especially in high salt containing formations) - fatty alcohol ether sulfates, - fatty alcohol ether sulfonates and ether carboxylates (- carboxymethylated fatty alcohol ethoxylates) have shown good performance. Biosurfactants are in discussion. 

Fatty alcohol ether sulfate and non-ylphenol ether sulfate separation of oligomers after hydrolysis to the corresponding nonionic compounds Silica Gel G 45 5 2.5 Ethyl acetate/ NH40H/Me0H Modified Dragendorff reagent 7... 

To a solution of 8 g of lithiim alanate in 250 ml of diethyl ether was added in 15 min 24 g (0.3 mol) of 2-penten-4-yn-l-ol (III, Exp. 57). The diethyl ether began to reflux and a rubber-like greyish precipitate was formed. After heating for 1 h under reflux the flask was placed in an ice + ice-water bath and water (150 ml) was added dropwise with vigorous stirring. After this hydrolysis procedure the ethereal solution was decanted and the aqueous jelly layer was extracted ten times with diethyl ether. The ethereal extracts were dried (without washing) over magnesium sulfate and subsequently concentrated in a water-pump vacuum. 

The absorbate containing the mixed ethyl sulfates is hydroly2ed with enough water to give an approximately 50—60% aqueous sulfuric acid solution. The hydrolysis mixture is separated in a stripping column to give dilute sulfuric acid bottoms and a gaseous alcohol—ether—water mixture overhead. The overhead mixture is washed with water or dilute sodium hydroxide and then purified by distillation (63,65,66,68,69). 

Diethyl ether is the principal by-product of the reaction of ethyl alcohol with diethyl sulfate. Various methods have been proposed to diminish its formation (70—72), including separation of diethyl sulfate from the reaction product. Diethyl sulfate not only causes an increase in ether formation but is also more difficult to hydroly2e to alcohol than is ethyl hydrogen sulfate. The equiUbrium constant for the hydrolysis of ethyl hydrogen sulfate is independent of temperature, and the reaction rate is proportional to the hydrogen ion concentration (73—75). 

Quaternary ammonium compounds biocidal activity mechanism, 1, 401 toxicity, 1, 124 Quaternization heterocyclic compounds reviews, 1, 73 ( )-Quebrach amine synthesis, 1, 490 Queen substance synthesis, 1, 439 4, 777 Quercetin occurrence, 3, 878 pentamethyl ether photolysis, 3, 696 photooxidation, 3, 695 Quercetrin hydrolysis, 3, 878 Quinacetol sulfate as fungicide, 2, 514 Quinacridone, 2,9-dimethyl-, 1, 336 Quinacridone pigments, 1, 335-336 Quinacrine... 

Historically, simple Vz-alkyl ethers formed from a phenol and a halide or sulfate were cleaved under rather drastic conditions (e.g., refluxing HBr). New ether protective groups have been developed that are removed under much milder conditions (e.g., via nucleophilic displacement, hydrogenolysis of benzyl ethers, and mild acid hydrolysis of acetal-type ethers) that seldom affect other functional groups in a molecule. 

Pyrogallol monomethyl ether has been prepared by the methylation of pyrogallol with dimethyl sulfate or methyl iodide by the decarboxylation of 2,3-dihj droxy-4-methoxy-benzoic acid and by the methylation of pyrogallol carbonate with diazomethane and subsequent hydrolysis. The method described is taken from the improved procedure of Baker and Savage for the preparation of pyrogallol monomethyl ether from o-vanillin by oxidation with hydrogen peroxide. 

Excess lithium is destroyed by the c irc/w/addition of 1-2 ml of ethanol, and hydrolysis of the reaction mixture is then effected by the addition of a mixture of ice (50 g) and water (100 ml). The solution is then acidified to pH 2 by the addition of 5 A hydrochloric acid, followed by rapid stirring for 1 or 2 minutes to hydrolize the HMPT. The aqueous solution is extracted with ether, the ether solution is dried with magnesium sulfate, then filtered, and the ether is evaporated. The product is isolated by distillation of the residue. 

A mixture of 100 g (0.6 mole) of 1-morpholino-l-cyclohexene, 28.8 g (0,4 mole) of /3-propiolactone, and 100 ml of chlorobenzene is placed in a 500-ml round-bottom flask fitted with a condenser (drying tube). The mixture is refluxed for 4 hours. The solvent and excess enamine are removed by distillation at aspirator pressure. (The residue may be distilled to afford the pure morpholide, bp 187-18871 rnm, 1.5090.) Basic hydrolysis may be carried out on the undistilled morpholide. To the crude amide is added 400 ml of 10% sodium hydroxide solution. The mixture is cautiously brought to reflux, and refluxing is continued for 2 hours. The cooled reaction mixture is made acidic (pH 4) and is extracted three times with ether. The combined ether extracts are washed twice with 5 % hydrochloric acid solution and twice with water. The ethereal solution is dried (sodium sulfate), then filtered, and the solvent is removed (rotary evaporator). The residue may be recrystallized from petroleum ether-benzene, mp 64°. 

The enol-sulfate form (I), which is the precursor of the luciferin in the bioluminescence system of the sea pansy Renilla (Hori et al., 1972), can be readily converted into coelenterazine by acid hydrolysis. The enol-sulfate (I), dehydrocoeienterazine (D) and the coelenterazine bound by the coelenterazine-binding proteins are important storage forms for preserving unstable coelenterazine in the bodies of luminous organisms. The disulfate form of coelenterazine (not shown in Fig. 5.5) is the luciferin in the firefly squid Watasenia (Section 6.3.1). An enol-ether form of coelenterazine bound with glucopyra-nosiduronic acid has been found in the liver of the myctophid fish Diapbus elucens (Inoue et al., 1987). 

B) Hydrolysis of Ethyl Benzoylacefoacetate.—Thirty-two grams (0.6 mole) of ammonium chloride is dissolved in 150 cc. (8.3 moles) of water, in a 500-cc. Erlenmeyer flask, and 10 cc. (0.15 mole) of ammonia (sp. gr. 0.9) added. After the solution is warmed to 420, 58.5 g. (0.25 mole) of ethyl benzoylacetoacetate at 200 is added quickly, and the mixture shaken (Note 3). The flask is placed in a water bath at 420 for exactly ten minutes and then cooled rapidly by placing it in an ice bath. The solution is extracted twice with 100-cc. portions of ether, and the ether solution dried with anhydrous magnesium sulfate. The ether is distilled, and the residue distilled in vacuo the yield is 37.0-37.5 g. (77-78 per cent of the theoretical amount) of ethyl benzoylacetate boiling at 132-1370 at 4 mm., or 165-169° at 20 mm. 

---