Ester sulfonates precipitation

A simple yet highly effective nonbleach, two-step process had been described for purifying palm Cie ig potassium methyl ester sulfonates [54]. In the first step, water is added to the impure surfactant mixture. The temperature of the system is maintained above the Krafft point of the surfactant, so that the surfactant and associated impurities are completely solubilized. Once completely dissolved, the surfactant mixture is allowed to cool, and the potassium-neutralized methyl ester sulfonate precipitates out selectively. In the second step, the purified surfactant is recovered by gravity or pressure filtration or by centrifugation, followed by drying. 

After having been washed with 50 cc of water the benzene layer is dried over potassium carbonate, filtered, allowed to stand over 10 g of alumina for about VA hours for partial decolorization, filtered again and concentrated under reduced pressure. The oily base which remains as a residue is directly converted into the tartrate. A solution cooled to 0°C, of 6.50 g of the free base in 100 cc of acetic acid ethyl ester is thoroughly shaken and poured into an ice cold solution of 2.66 g of tartaric acid in 410 cc of acetic acid ethyl ester. The precipitated, analytically pure, tartrate of 3-methylsulfinyl-10-[2 -N-methyl-piperidyl-2")-ethyl-1 ]-phenothiazine melts at 115° to 120°C (foam formation) and sinters above B0°C. The base Is reacted with benzene sulfonic acid in a suitable solvent to give the besylate. 

The history of the discovery of amino acids is closely related to advances ia analytical methods. Initially, quantitative and qualitative analysis depended exclusively upon crystallization from proteia hydrolysates. The quantitative precipitation of several basic amino acids including phosphotungstates, the separation of amino acid esters by vacuum distillation, and precipitation by sulfonic acid derivatives were developed successively duriag the last century. 

Fujiwara et al. studied the precipitation phase boundary diagrams of the sodium salts of a-sulfonated myristic and palmitic acid methyl esters in the presence of calcium ions [61]. The time dependency of the precipitation showed that the calcium salts have an extremely slow crystallization rate at room temperatures. This is the reason for the good hardness tolerance of the a-sulfonated fatty acid methyl esters. 

Alternatively, dissolve 220 g 4-benzyloxy-3-indoleacetic acid (or equimolar amount other indoleacetic acid) in 2 L absolute methanol and reflux six hours in the presence of 20 g Dowex 50X8 sulfonic acid resin. Filter (decolor with carbon if desired) and concentrate below 35° until precipitation starts then cool to precipitate and filter to get 200 g of the methyl ester. Add 200 g of the ester to 600 ml 40% aqueous methylamine over twelve hours with vigorous stirring. Filter, wash precipitate with water and dry to get 187 g of the N-methyl-acetamide (reflux two hours in 500 ml benzene to remove unreacted ester). 24 g of the acetamide in 300 ml tetrahydrofuran is added dropwise to 10 g lithium aluminum hydride in 300 ml tetrahydrofuran reflux ten hours, cool to 15° and add dropwise with stirring 50 ml ethyl acetate. Reflux two hours and proceed as above to get 15 g (II) or analog. 

The hydrolysis/elimination reaction of the f-butyl methacrylate brushes is not easily driven to full conversion. Whereas linear f-butyl methacrylate chains are fully converted to polyacrylic acid in dioxane with catalytic amounts of toluene sulfonic acid the cylindrical brush structures precipitated at about 50% conversion (sample PMA-PBMA31-MAS50). Complete cleavage of the ester groups was achieved, however, by dissolving the partial-... 

At first, the substituent replaced one end of the CD hydroxyl. Then, through multipoint connection of hydroxyl sites or stereochemical structure of the substituent itself, capped CDs, i.e. CDs with a cover of the substituent, could be formed. Capped CDs can be used to enhance the inclusion ability of the CD and improve molecular recognition of the specificity guest. A typical example is the basket CD which can be obtained by the reaction between biphenyl-4, 4 -di chloride and fi-CD at A, D-position, resulting in sulfonic esters. Then the reaction with potassium iodide to form the di-iodo-/3-cyclodextrin. di-iodo-j8-CD can be precipitated by using H2O / (CH2CH2)Cl4 (20 1) at 0°C. After reactingwith 10-fold excess of aza-crown ether in dry DMF under the protection of the chlorine reaction at 55 C for 24 h, the solvents are removed by evaporation. Purification can be achieved by sephadex LH-20 column with DMF/H2O (1 1). 

Mixtures of hydrocarbons with calcium alkyl phosphate particles are known to be effective antifoams in the context of domestic textile machine washing where wash cycles can last for up to 1 h and involve temperature ranges from 30°C to 95°C (see Section 8.2.4.1) [43, 44]. Under these circumstances, little or no deactivation of antifoam effectiveness is apparent. Mixtures of hydrocarbons with alkyl phosphoric acid esters also function as antifoams in this context provided the aqueous phase has a high enough pH and calcium ions are present [43, 44] so that the calcium salts can precipitate as particles in situ at the relevant hydrocarbon-water interface. This behavior is of course analogous to that shown by mixtures of oleic acid and hexadecane when dispersed in an aqueous phase under similar conditions [45]. As with the preformed calcium alkyl phosphate particles, no deactivation of antifoam effectiveness is observed in the case of in situ formation of the precipitates. Indeed, it has been observed that continuous aeration for several hours, using a circulating Ross-Miles apparatus at 90°C (see Section 2.2.3), of an aqueous solution of a blend of a commercial sodium dodecylbenzene sulfonate and an ethoxylated alcohol in the presence of mixtures of a hydrocarbon and an alkyl phosphoric acid ester (dispersed... 

Sulfur Chemistry - Two facile methods of the heretofore difficult sulfoxide to sulfide reduction have been accomplished with dilsobutyl aluminum hydride and dichloroborane in THF at 0 . With the latter reagent, ketones, esters, and amides remain unaffected. A review on sulfoximes and derivatives as synthetic reagents presents some new methods for the preparation of various oxiranes, aziridines, alcohols, cyclopropanes, and alkenesAllylic sulfoxide anions have proven useful for the synthesis of ally lie alcohols, including trisubstltuted olefinic allylic alcohols. Transesterification between a dialkylacylphosphonate and a sulfonic acid yields sulfonate esters. The oxidation of aliphatic mercaptans to sul-finio acids with the use of m-chloroperbenzoic acid is especially useful in that the excess perbenzolc acid is removed by precipitation at -80. ... 

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