Ether sulfates 1,4-dioxane

An analysis of alcohol and alcohol ether sulfates should determine the anionic active matter, the unsulfated matter, the inorganic sulfate content, the chloride content, and water. Other more precise analysis must determine the alkyl chain distribution of the alcohol and in the case of alcohol ether sulfates the number of ethoxy groups and its distribution, as well as other more specialized determinations, such as the content of 1,4-dioxane and other impurities. 

Determination of 1,4-Dioxane in Ether Sulfates by Headspace Chromatography... 

Principle. The content of 1,4-dioxane in ether sulfates is determined by headspace gas chromatography according to the standard additions method. The method is suitable for all ether sulfates and gives reliable results independent of chain length distribution and water content. 

Apart from the conversion of peroxides to useful products, it is sometimes necessary to reduce peroxides, and especially hydroperoxides formed by auto-oxidation. Such compounds are formed especially in hydrocarbons containing branched chains, double bonds or aromatic rings, and in ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, etc. Since most peroxidic compounds decompose violently at higher temperatures and could cause explosion and fire it is necessary to remove them from liquids they contaminate. Water-immiscible liquids can be stripped of peroxides by shaking with an aqueous solution of sodium sulfite or ferrous sulfate. A simple and efficient way of removing peroxides is treatment of the contaminated compounds with 0.4 nm molecular sieves [669]. 

Benzene, Arsenic trichloride, Aluminum chloride. Hexanes Acetic anhydride. Nitric acid, Hexamine, Acetic acid, Methylene chloride. Sodium bicarbonate, Magnesium sulfate, Dioxane, Hydrogen chloride, Acetone, Sodium azide m-phenylenediamine, Methanol, Sodium carbonate, Ethyl chloromate, Ethylene glycol dimethyl ether, Sulfuric acid, Nitric acid... 

Using sulfur trioxide complexes with pyridine, dioxane, iV,iV-dimethyl-aniline, or bis(2-chloroethyl) ether, sulfated chitins have also been prepared for use as thickeners in pastes, adhesives, and drilling muds. ... 

Amidosulfuric acid or chlorosulfuric acid can also be used for the sulfation of alkyl polyglycol ethers. The formed sulfuric acid semi-ester can be neutralized by either caustic soda solution, ammonia or nitrilotri-ethanol. The acid reaction mixture has to be neutralized immediately so as to avoid disintegration reactions which take place in the acid environment. Such reactions would otherwise lead not only to dark by-products but also to the formation of dioxane. The ether sulfates produced nowadays cover all demands for safety from toxic by-products. 

Continuous process control that produces products within narrow specifications, with low color, and with minimal formation of impurities such as 1,4-dioxane in alcohol ether sulfates and sultones in AOS... 

Ether sulfates may contain low levels of 1,4-dloxane, both because of impurities in the starting ethoxylate and because of formation of dioxane during the sulfation reaction (79). This analysis is discussed with the characterization of nonionic surfactants (Chapter 2). 

HPLC with UV detection at 200 nm has been proposed for determination of dioxane in ether sulfates and in cosmetics, with preliminary separation by solid phase extraction (56,57). While the HPLC procedure is too prone to give false positives to be very useful for trace analysis, it may be that solid phase extraction could be applied to GC analysis, making an expensive headspace apparatus or time-consuming distillation unnecessary. HPLC determination of EO and PO can be performed after formation of the dithiocarbam-oyl esters, with detection limits in the 0.5 ppm range (58). 

For extreme confidence in determination of 1,4-dioxane, headspace GC-MS may be used with an isotope dilution procedure, making use of the commercially available deuter-ated analog of dioxane (67). The precision of results becomes poor with decreasing analyte concentration. A coefficient of variation of about 30% is reported for determination of EO at the 0.2-30 ppm level in an alkyl ether sulfate, using the standard addition method of calibration (a single standard addition per sample) (68). 

Pyrolysis GC of alkyl sulfates in the presence of phosphoric acid or P2O5 gives olefins of the same length as the original alkyl chain, with the double bond distributed along the chain (16). Pyrolysis without acid yields mainly a-olefins as opposed to internal olefins. Ether sulfates are distinguished from alcohol sulfates by the presence of the characteristic decomposition products acetaldehyde and 1,4-dioxane (19). 

The alcohol ether sulfates (AES) represent approximately 9% of industrialized surfactant consumption. Because of their perceived mildness, they are used primarily in personal care products. They have a strong position in terms of raw materials since they can be made from either petroleum or renewable (i.e., agriculturally derived) raw materials. One possible disadvantage of AES surfactants is the possible presence of dioxane derivatives as a byproduct of the ethoxylation process. Although modem processes have been shown to effectively eliminate the presence of such contaminants, emotional factors and lack of good information must always be considered, especially where consumer products are concerned. 

The mixture is distilled until most of the ether has been removed and then refluxed for 8 hr. Ethyl acetate is added to decompose the excess reagent and concentrated aqueous sodium sulfate is then added until the precipitate begins to adhere to the sides of the flask. Finally ca. 100 g of solid sodium sulfate is added, the salts are removed by filtration and washed well with dioxane. Evaporation of the solvent gives a solid residue which is dissolved in 60 ml of chloroform and shaken with 3.5 g of manganese dioxide for 16 hr. Subsequently another 3.5 g of manganese dioxide is added and shaking continued for a further 16 hr. The solid is removed by filtration and washed well with hot chloroform. Evaporation of solvent and crystallization of the residue from acetone-hexane affords 0.51 g (72%) of 17a-hydroxy-17jff-ethylandrost-4-en-3-one mp 145-148°. 

Hydroxy-B-homo-5a-cholestan-7-one acetate (54b) A solution of 3/3-hydroxy-5a-cholestan-7-one acetate (51b 5 g mp 146-148°) in dioxane-ethanol (100 ml, 1 1) is placed in a 250 ml three-necked flask equipped with a mechanical stirrer and thermometer and is cooled to 0° (iee-salt bath). Powdered potassium cyanide (7.3 g) is added portionwise with stirring. Acetic acid (8 ml) is then added dropwise with constant stirring over 30 min. The resultant mixture is stirred for 1 hr at 0° C and for an additional 2 hr at room temperature. It is then poured into ice water (200 g ice, 100 ml water) and after standing for 1 hr the precipitate is collected by filtration. The product is dissolved in ether (100 ml), the ether solution is washed with 5% sodium bicarbonate, water and dried over anhydrous sodium sulfate. The filtrate is evaporated at reduced pressure and the solid residue (5.1 g) is crystallized from ethyl acetate (30 ml) to yield 2.8 g of cyanohydrin (52b) mp 160-164° repeated crystallization from the same solvent gives a product mp 164-167°. An alternative method of isolation of the cyanohydrin is used when 100 g or larger quantities are worked up. The reaction mixture is poured directly into a mixture of ice water and sodium bicarbonate, the precipitate (mp 155-156°) is washed well with water, dried and used directly for the next step. 

To a solution of 13 parts of compound A and 12 parts by volume of absolute pyridine in 80 parts by volume of absolute dioxane there are added dropwise and under constant stirring 35 parts of 3,4.5-trimethoxybenzoyl chloride dissolved in 70 parts by volume of absolute dioxane in the course of 30 minutes. The mixture is stirred for a further 3 hours at a temperature of 100°C and the excess solvent is then evaporated in vacuo. The residue of the evaporation is treated with ethyl acetate and saturated sodium carbonate solution, whereafter the organic phase is separated, treated with water, dried with sodium sulfate and the solvent is removed in vacuo. The residue thus obtained is taken up In ether and separated from 4 parts of insoluble trimethoxybenzoic acid anhydride by filtration. After evaporation of the ether there are obtained 32.5 parts of N,N -dimethyl-N,N -bis-[3-(3,4,5-trlmethoxybenzoxy)-propyl] -athylene diamine, corresponding to a yield of 86% of the theoretical. MP 75°C to 77°C. 

A mixture of 4.9 grams of 5,6-dihydro-6-oxo-morphanthridine, 37 ml of phosphorus oxychloride and 1.5 ml of dimethylaniline Is heated for 3 hours at reflux. The viscous oil, obtained by evaporation of the reaction mixture in vacuo at 60°C, Is diluted with 20 ml of absolute dioxane and, after adding 30 ml of N-methylpiperazine, heated for 4 hours at reflux. The resulting clear solution Is evaporated in vacuo at 60°C to dryness. The residue is distributed between ether and ammonia water. The ethereal solution is separated, washed with water and then extracted with 1 N acetic acid. The acetic acid extract is mixed with ammonia water and then extracted with ether. The ethereal solution is washed with water, dried over sodium sulfate, filtered through alumina and evaporated. 

Dasler, W. et al., Ind. Eng. Chem. (Anal. Ed.), 1946,18, 52 Like other monofunctional ethers but more so because of the four susceptible hydrogen atoms, dioxane exposed to air is susceptible to autoxidation with formation of peroxides which may be hazardous if distillation (causing concentration) is attempted. Because it is water-miscible, treatment by shaking with aqueous reducants (iron(II) sulfate, sodium sulfide, etc.) is impracticable. Peroxides may be removed, however, under anhydrous conditions by passing dioxane (or any other ether) down a column of activated alumina. The peroxides (and any water) are removed by adsorption onto the alumina, which must then be washed with methanol or water to remove them before the column material is discarded [1], The heat of decomposition of dioxane has been determined (130-200°C) as 0.165 kJ/g. 

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