Ethyl acetate sulphoxide

A new approach to the resolution of sulphoxides 242 was recently reported by T oda and coworkers282. It takes advantage of the fact that some sulphoxides form crystalline complexes with optically active 2,2 -dihydroxy-l, 1-binaphthyl 243. When a two-molar excess of racemic sulphoxide 242 was mixed with one enantiomeric form of binaphthyl 243 in benzene-hexane and kept at room temperature for 12 h, a 1 1 complex enriched strongly in one sulphoxide enantiomer was obtained. Its recrystallization from benzene followed by chromatography on silica gel using benzene-ethyl acetate as eluent gave optically pure sulphoxide. However, methyl phenyl sulphoxide was poorly resolved by this procedure and methyl o-tolyl, methyl p-tolyl, s-butyl methyl and i-propyl methyl sulphoxides did not form complexes with 243. 

Figure 55. Dependence of the thermodynamic properties of ethyl acetate on co-solvent mole fraction in dimethyl sulphoxide + water mixtures at 298 K (Fuchs et al., 1974).

Nitrosolysis of camphor ethyl acetal with ethanolic ethyl nitrite in sulphur dioxide yields the orthoester oxime (205) which is rapidly dehydrated by excess acetal to the orthoester nitrile which then reacts with sulphur dioxide to form the ester nitrile and diethyl sulphite.Further papers in this section include the full paper on ozonolysis of silyl ethers (Vol. 5, p. 33), another synthesis of camphor-enol trimethylsilyl ether (cf. Vol. 6, p. 41)/°° the conversion of camphor oxime with Grignard reagents into the corresponding imine with no aziridine formation/° the preparation of (206) by treating bornylene with trichloroacetyl isocyanate/ the oxidation of thiocam-phor to the 5-oxide and alkylation in the presence of thallium(i) ethoxide to a/S-unsaturated sulphoxides/ and the free-radical C-3 alkylation of camphor with alkenes. " ... 

Tervalent phosphorus acid derivatives are normally liquids or low-melting solids which can be purified by distillation, or sometimes by recrystallization from a non-polar solvent. Most are oxidized in contact with the atmosphere, and many are easily hydrolyzed, so they must be kept under an inert atmosphere (N2 or Ar) during all manipulations. Flasks should be predried and solvents dried and deoxygenated before use. Tervalent phosphorus acid derivatives are, with few exceptions, thermally stable and can be kept indefinitely in ampoules under an inert gas (many halophosphines dissolve stopcock grease and should not be kept in stoppered flasks for prolonged periods). Inert solvents are hydrocarbons, ethers and, for most compounds, dichloromethane, ethyl acetate and tertiary amines. Aminophosphines react vigorously with tetrachloromethane and slowly with trichloromethane, and most tervalent phosphorus acid derivatives are oxidized by dimethyl sulphoxide and react with alcohols. 

The 5,6-dihydroxyindoles, including the parent system 1, are usually white-to-grey crystalline solids that melt with extensive decomposition and darkening. They are soluble in alcoholic solvents and acetone, less in acetonitrile, ethyl acetate, dimethyl sulphoxide (DMSO), tetrahydrofuran (THF), and water, and only sparingly soluble in hydrocarbons, e.g. benzene and light petroleum. A detailed physicochemical characterization of compound 1 was described by Murphy and Schultz (85JOC5873) (85JOC2790). The values for the first and second ionizations of indole 1 were determined as 8.9 and > 10.2, respectively. 5,6-Dihydroxy-1-methylindole 3 has values of 8.4 and 10.7 in water. 

Sucrose esters are manufactured by transesterification of sucrose with fatty acid methyl esters in a suitable solvent system where both components are soluble, such as dimethylformamide or dimethyl-sulphoxide (Benson, 1967). The sucrose esters are purified by distillation and crystallization from e.g. ethyl acetate in order to remove the solvent completely. For food use the content of dimethylformamide must be less that 1 mg/kg. An alternative... 

The contributions made by these pathways in proton transfer between amines and their conjugate acids have been determined [193] and the results are shown in Table 13. The rate coefficient kt refers to the direct proton transfer mechanism and k2 is for proton transfer through a solvent bridge. The available evidence for carbon acids suggests that proton transfer occurs directly between acid and base and an intervening solvent molecule is not involved [123,194]. This evidence is mostly based on the magnitude of the solvent isotope effect, and results for reactions involving nitroparaffins, acetals, and diazocompounds have been reviewed [123]. In a different approach to this question, the rate expression for the acid catalysed decomposition of ethyl vinyl ether in water/dimethyl-sulphoxide was measured [195] and shown to consist of two terms (111). 

The Diels-Alder reaction between fiuoranil and 1-acetoxybutadiene in benzene, which gives the adduct (121), occurs at room temperature when the solution is in contact with silica gel, and the reaction is believed to take place within the pores of the adsorbent the technique may be of general applicability.i Fiuoranil reacts with the ethyl ester of DL-a-alanine in ethanol to give the 2,5-disubstituted product (122), and a similar reaction apparently occurs with ethyl-glycine. The reaction of 2,3,4-trifluoro-l-nitroanthraquinone with amines (NHa, MeNHa, EtaNH, or piperidine) in benzene gives mixtures of 2- and 4-substituted products, but some 3-substitution also occurs when the solvent is dimethyl sulphoxide l,3,4-trifluoro-2-nitroanthraquinone reacts only at the 3-position with the same amines in either solvent. Treatment of the products of these reactions with zinc in acetic acid results in simple reduction of -NOa to -NHa. ... 

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