Alkyl sulfonates hydrolysis

One hydrolytic method that is useful for the preparation of ketones is the hydrolysis of dithianes. 1.3-Dithiane can be alkylated by treatment with butyl lithium followed by an alkylating agent. The two sulfurs flanking the acetal carbon acidify the protons on that carbon such that butyl lithium can remove one giving a sulfur-stabilized anion. This anion reacts with alkyl halides or sulfonates to give alkylated products. This sequence can be repeated to give a bis-alkylated product. Hydrolysis then yields a ketone. Ditliioacetals are much more resistant to hydrolysis than acetals and thus Hg2+ is often used to promote efficient hydrolysis. 

The exception noted for hydroxyl ions in rule (2) is well established for other sulfonic esters of carbohydrates, which therefore differ from simple alkyl sulfonates. An example of hydrolysis of an exo sulfonyloxy group is provided by the compound described as methanesulfonyl-monochloro-l,4 3,6-dianhydrosorbitol which must now be designated 1,4 3,6-dianhydro-5-chloro-5-deoxy-2-0-mesyl-L-iditol reaction with sodium hydroxide affords the free, hydroxy compound of the same configuration. Examples of the hydrolysis of endo sulfonyloxy groups are not available in the dianhydrohexitols, but the endo tosyloxy group in the stereochemically equivalent 3,6-anhydro-l, 2-0-isopropylidene-5-0-tosyl-D-glucofuranose (LXVII) is hydrolyzed by sodium hydroxide to the corresponding hydroxyl... 

The anion of 2-(methoxyethoxymethoxy)cyclopropyl phenyl sulfone (methoxyetho-xymethoxy = MEM) is a d -synthon for a,)8-unsaturated aldehydes ". The anion is readily formed by treating 2-(MEM)cyclopropyl phenyl sulfone (359) with n-butyllithium in THE at — 78°C. Treatment of the anion 360 with aliphatic primary bromides or allyl bromide produces the alkylated sulfone 361 in very good yields. Hydrolysis of the MEM-protecting group was readily performed by treatment with aqueous tetrafluoroboric acid to furnish the cyclopropanol sulfone (362). Treatment with aqueous sodium bicarbonate produced the corresponding aldehydes 363 in 70-90 % yields. 

Simple sulfonyl carbanions which do not contain additional carbanion-stabilising groups, e.g. carbonyl groups or heteroatoms, can be readily alkylated in high yield by modern techniques with the use of alkyllithiums and lithium amide bases. A number of allylic halides have been successfully used. In allylic halides, the halogen directly attached to the double-bonded carbon is relatively inert towards nucleophilic attack (Scheme 41). In this way, sulfones (96) can be transformed via desulfonation into vinyl halides (97) or into ketones (98) by hydrolysis (Scheme 41). In contrast to ordinary alkyl sulfones, triflones (99) can be alkylated under mildly basic conditions (potassium carbonate in boiling acetonitrile) (Scheme 42). The ease of carbanion formation from triflones (99) arises from the additional electron-withdrawing (-1) effect of the trifluoromethyl moiety. 

The vast literature on applications of PTC in substitution reactions is mainly restricted to nucleophilic substitution reactions with an anionic reagent. However, recently the use of PTC in electrophilic reactions, like diazotization andazocou-pling C-and N-nitrosation, C-alkylation, acid hydrolysis of esters, chloromethylation, nitrite-initiated nitrations, and so on have been reported(Velichko et al., 1992 Kachurin et al., 1995). Alkylbenzene sulfonates and lipophilic sodium tetrakis[3,5-bis(trifluoromethyl)phenylboranate are typical electrophilic PT catalysts. Lipophilic dipolar molecules of the betaine type and zwitterionic compounds also function well as PT agents for both nucleophilic as well as electrophilic reactions. 

The sulfur trioxide is not used in the free state but in the form of an adduct with, e.g., pyridine, dimethylformamide, or dioxane the yields of sodium alkyl sulfonates obtained after alkaline hydrolysis are up to about 70%. 

It is possible to abstract a proton from a 2-alkylated-1,3-dithiane and perform a second alkylation reaction. If the 2-alkylated-1,3-dithiane is prepared from the aldehyde with propane-1,3-dithiol, then after alkylation and hydrolysis the sequence provides a method for converting an aldehyde into a ketone. Starting with the commercially available 1,3-dithiane, an alkyl halide or sulfonate can be converted into the homologous aldehyde. Two alkyl groups can actually be introduced successively without isolation of the intermediates and this has been applied to the synthesis of three- to seven-membered cyclic ketones. 

Alkyl sulfonates make more sense in industry application. The reason is that flie raw alcohols of sulfates are costly. Meanwhile, the hydrolysis reaction of alkyl sulfates often takes place in water ... 

From a chemical standpoint, there is an important difference between the above alkyl sulfates and the alkyl sulfonates. In the former, the sulfur atom is linked to the carbon chain via an oxygen atom in the latter, the sulfur atom is directly linked to the carbon atom. The C—S bond makes sulfonates not prone to hydrolysis and they can be stored in a concentrated sulfonic acid form. 

Because of good thermal and hydrolytic stability, excellent mechanical and chemical stability, low cost, and commercial availability of sulfonated aromatic hydrocarbon polymers, recent research has focused on the synthesis and development of sulfonated aromatic hydrocarbon polymers specifically for high-temperature PEMFCs. Typical examples include sulfonated poly(ether ether ketone) (SPEEK) or poly(ether ketone ketone) (SPEKK) [1,2], sulfonated poly(ether sulfone) (SPSE) [3], alkyl sulfonated polybenzimidazole (PBI), sulfonated naphthalenic polyinrides (sNPl) [4-6], sulfonated polyCphenylene sulfide) [7,8]. Both post- and pre-sulfona-tion methods have been used in the past. Other than the post-sulfonation modification of aromatic polymers, recently, efforts have been dedicated to direct polycondensation from sulfonic acid containing monomers to synthesize sulfonated polymers [9]. The latter approach, namely pre-sulfonation, is widely applied because of the ease of controlling sulfonation degree and deactivated sites in the arylene backbones, which further avoid side reactions such as decomposition and hydrolysis of polymers resulted from the post-sulfonation method. 

A mixture of anionic surfactants (salts of fatty acids (currently named soaps), alkyl sulfates and alkyl sulfonates may be determined by three titrations. These three surfactants are titrated using dichlorofluorescein as indicator a dimidium bromide and disulfine blue mixture are used for titration of alkyl sulfates and alkyl sulfonates, while disulfine blue is used for alkyl sulfonates titration after acid hydrolysis (Cozzoli, 1993). 

The kinetics of formation and hydrolysis of /-C H OCl have been investigated (262). The chemistry of alkyl hypochlorites, /-C H OCl in particular, has been extensively explored (247). /-Butyl hypochlorite reacts with a variety of olefins via a photoinduced radical chain process to give good yields of aUyflc chlorides (263). Steroid alcohols can be oxidized and chlorinated with /-C H OCl to give good yields of ketosteroids and chlorosteroids (264) (see Steroids). /-Butyl hypochlorite is a more satisfactory reagent than HOCl for /V-chlorination of amines (265). Sulfides are oxidized in excellent yields to sulfoxides without concomitant formation of sulfones (266). 2-Amino-1, 4-quinones are rapidly chlorinated at room temperature chlorination occurs specifically at the position adjacent to the amino group (267). Anhydropenicillin is converted almost quantitatively to its 6-methoxy derivative by /-C H OCl in methanol (268). Reaction of unsaturated hydroperoxides with /-C H OCl provides monocyclic and bicycHc chloroalkyl 1,2-dioxolanes. 

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

The enamines derived from cyclic ketones give the normal alkylated products, although there is some evidence that unstable cycloadducts are initially formed (55b). Thus the enamine (28) derived from cyclohexanone and pyrrolidine on reaction with acrylonitrile, acrylate esters, or phenyl vinyl sulfone gave the 2-alkylated cyclohexanones (63) on hydrolysis of the intermediates (31,32,55,56). These additions are sensitive to the polarity of the solvent. Thus (28) in benzene or dioxane gave an 80% yield of the... 

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. 

Oxime carbamates have high polarity and solubility in water and are relatively chemically and thermally unstable. They are relatively stable in weakly acidic to neutral media (pH 4-6) but unstable in strongly acidic and basic media. Rapid hydrolysis occurs in strongly basic aqueous solutions (pH > 9) to form the parent oxime/alcohol and methylamine, which is enhanced at elevated temperature. Additionally, oxime carbamates are, generally, stable in most organic solvents and readily soluble in acetone, methanol, acetonitrile, and ethyl acetate, with the exception of aliphatic hydrocarbons. Furthermore, most oxime carbamates contain an active -alkyl (methyl) moiety that can be easily oxidized to form the corresponding sulfoxide or sulfone metabolites. 

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