Phase hydrogen sulfate

Ethyl Acetate. Catalysts proposed for the vapor-phase production of ethyl acetate include siUca gel, zirconium dioxide, activated charcoal, and potassium hydrogen sulfate. More recendy, phosphoric-acid-treated coal (65) and calcium phosphate (66) catalysts have been described. 

AcCl, NaOH, dioxane, Bu4N HSO, 25°, 30 min, 90% yield. Phase-transfer catalysis with tetra-n-butylammionium hydrogen sulfate effects acylation of sterically hindered phenols and selective acylation of a phenol in the presence of an aliphatic secondary alcohol. 

Fluonnated allylic ethers are prepared under phase-transfer catalysis (PTC) in the presence of tetrabutylammonium hydrogen sulfate (TBAH) fJ] (equation 2)... 

The hydrogen sulfate was dissolved in water and the pH of the solution was adjusted to 5.6 (pH-meter) with 0.1 N sodium hydroxide solution. The water solution was evaporated to dryness and the residue dried with absolute ethanol/benzene and once more evaporated to dryness. The remaining crystal mixture was extracted in a Soxhiet extraction apparatus with absolute methanol. From the methanol phase the sulfate of 1-(3, 5 -dihydroxyphenyl)-2-(t-butylaminoj-ethanol crystallized. Melting point 246°C to 248°C. 

The sulfation reaction occurs in the liquid phase at approximately 35 °C. An 85 wt% alcohol yield could be realized. The reaction is similar to the sulfation of ethylene or propylene and results in a mixture of sec-butyl hydrogen sulfate and di-sec-butyl sulfate. The mixture is further hydrolyzed to sec-butanol and sulfuric acid ... 

Eatough DJ, VF White, LD Hansen, NL Eatough, JL Cheney (1986) Identification of gas-phase dimethyl sulfate and monomethyl hydrogen sulfate in the Los Angeles atmosphere. Environ Sci Technol 20 867-872. 

The mesogenic units with methylenic spacers were prepared by reacting the sodium salt of either 4-methoxy-4 -hydroxybiphenyl or 4-phenylphenol with a bromoester in DMF at 82° C for at least 4 hours in the presence of tetrabutylammonium hydrogen sulfate (TBAH) as phase transfer catalyst. In this way, ethyl 4-(4-oxybi-phenyl)butyrate, ethyl 4-(4-methoxy-4 -oxybiphenyl)butyrate, ethyl 4-(4-oxybiphenyl)valerate, ethyl 4-(4-methoxy-4 -oxybiphenyl)-valerate, n-propyl 4-(4-oxybiphenyl)undecanoate and n-propyl 4-(4-methoxy-4 -oxybiphenyl)undecanoate were obtained. These esters were hydrolyzed with base and acidified to obtain the carboxylic acids. The corresponding potassium carboxylates were obtained by reaction with approximately stoichiometric amounts of potassium hydroxide. Experimental details of these syntheses were described elsewhere (27). 

After die reaction the two phase separated. Sulfur Conversion measure by GC from Organic Phase, Hydrogen Peroxide and Sulfate Concentration measured from aqueous phase. 

The dimer of chloro(l,5-hexadiene)rhodium is an excellent catalyst for the room temperature hydrogenation of aromatic hydrocarbons at atmospheric pressure. The reaction is selective for the arene ring in the presence of ester, amide, ether and ketone functionalities (except acetophenone). The most useful phase transfer agents are tetrabutylammonium hydrogen sulfate and cetyltrimethylammonium bromide. The aqueous phase is a buffer of pH 7.6 (the constituents of the buffer are not critical). In all but one case the reaction is stereospecific giving cis products... 

Amine extraction of penicillins has been examined in a pilot scale extractor and its performance has been analyzed through suitable mathematical models 117-19]. Extraction efficiency as high as 90% was achieved under suitable conditions. The procedure for selection of volume ratios of the aqueous to organic phase and concentration ratio of carrier (Amberlite LA-2) to penicillin-G at a desired degree of extraction and enrichment has recently been described [20]. Ion-pair extraction of penicillin-V and phenoxy acetic acid with Amberlite LA-2 hydrochloride and tetrabutyl ammonium hydrogen sulfate can be effective in... 

Facilitated transport of penicilHn-G in a SLM system using tetrabutyl ammonium hydrogen sulfate and various amines as carriers and dichloromethane, butyl acetate, etc., as the solvents has been reported [57,58]. Tertiary and secondary amines were found to be more efficient carriers in view of their easy accessibility for back extraction, the extraction being faciUtated by co-transport of a proton. The effects of flow rates, carrier concentrations, initial penicilHn-G concentration, and pH of feed and stripping phases on transport rate of penicillin-G was investigated. Under optimized pH conditions, i. e., extraction at pH 6.0-6.5 and re-extraction at pH 7.0, no decomposition of peniciUin-G occurred. The same SLM system has been applied for selective separation of penicilHn-G from a mixture containing phenyl acetic acid with a maximum separation factor of 1.8 under a liquid membrane diffusion controlled mechanism [59]. Tsikas et al. [60] studied the combined extraction of peniciUin-G and enzymatic hydrolysis of 6-aminopenicillanic acid (6-APA) in a hollow fiber carrier (Amberlite LA-2) mediated SLM system. 

Amides from nitriles. One classical reagent for this reaction is H202-Na0H in a suitable solvent.3 This reaction can be carried out advantageously under phase-transfer catalyzed conditions.4 Tetra-n-butylammonium hydrogen sulfate is satisfactory the effectiveness varies with the structure of the nitrile. An excess of 30% H202 is used the solvent system is CH2C12 20% NaOH. Yields are 85-95%. 

The solubility of the components in the solvent must be sufficient. To improve the solubility, cosolvents can be used. Another possibility is the application of a two-phase system or an emulsion in the presence of phase-transfer catalysts. A two-phase system also has advantages in product isolation and continuous electrolysis procedures. A typical example is the synthesis of p-methoxy benzonitrile by anodic substitution of one methoxy group in 1,4-dimethoxybenzene by the cyanide ion (Eq. 22.21). The homogeneous cyanation system (acetonitrile, tetraethylammonium cyanide) [24] can be efficiently replaced by a phase-transfer system (dichloro-methane, water, sodium cyanide, tetrabutylammonium hydrogen sulfate) [71]. 

Retention of solutes and selectivity can be controlled by adjusting the type and concentration of the ion-pair reagent added and by selection of the type and concentration of the organic solvent in the mobile phase (135,168). The ion pair reagents most commonly used are tetra-alkylammonium salts such as cetrimide (155,156,177) and tetra-n-butylammonium (TBA). The TBA reagent can be used as TBA phosphate (159,184), TBA chloride (221), TBA hydrogen sulfate (188,189), or TBA hydroxide (168,175,183). 

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