Isobutyl compounds

The hydrolysis of various para-substituted a-methylstyrene oxides was studied using 10 EHs [184]. The hydrolysis of the isobutyl compound with the enzyme from A. niger WHS the key step in the synthesis of (S)-ibuprofen (Figure 6.65). The (R)-diol was recycled via chemical racemization. 

The synthesis of the flexible Isoleucine-isobutyl compound (9, Scheme 2) was lengthier, mainly as a consequence of the fact that the compound contains a butyl-carboxamide group capable of picking up binding interactions on the ST side of the protein. Synthesis of the key isobutyl-sllyl-methylamine compound 10 was achieved over 8 steps. The amine was then coupled in standard fashion with the P2 portion of the molecule and the prime-side side chain was modified to the desired amide 11. Deprotection of the diphenyl-silane using TFA, as described above, provided the target diol 9. 

Isobutyl halides and other isobutyl compounds rearrange readily to tert-butyl compounds for the older literature see Whitmore and Lux.869 However, PBr3 (see page 223) converts isobutyl alcohol into isobutyl bromide in good yield with less than 1% of tert-butyl bromide.869... 

R Tl compounds, eg, methyl [3003-15-4], ethyl [687-82-1], isobutyl [3016-08-8], and phenyl [3003-04-1] thaHium(III), are usuaHy prepared by the reaction between a dialkyl or diarylthaHium haHde and an organolithium reagent in ether (16) ... 

Cyanohydrins (qv) are formed by the reaction of glucose and similar compounds with hydrogen cyanide. The corresponding aminonitrile from methyl isobutyl ketone can be formed with ammonia and hydrogen cyanide. 

Cd/Cd compounds carbon tetrachloride chloroform Cr/Cr compounds CN-compounds /HCN Pb/Pb compounds Hg/Hg compounds methylene chloride methyl ethyl ketone methyl isobutyl ketone Ni/Ni compounds tetrachloroethylene toluene... 

Oxaziridines substituted in the 2-position with primary or secondary alkyl groups undergo decomposition at room temperature. In the course of some weeks, slow decomposition of undiluted compounds occurs, the pattern of which is analogous to that of acidic or alkaline N—O cleavage (Sections 5.08.3.1.3 and 4), Radical attack on a C—H bond in (109) effects N—O cleavage, probably synchronously (57JA5739). In the example presented here, methyl isobutyl ketone and ammonia were isolated after two hour s heating at 150 °C. 

Solvents. NBRs are soluble in aromatic hydrocarbons, chlorinated hydrocarbons, ketones, esters and nitroparaffin compounds. Solvents with high evaporation rate are acetone, methyl ethyl ketone, chloroform and ethyl acetate, among others. Solvents with slow evaporation rate are nitromethane, dichloropentenes, chloro-toluene, butyl acetate and methyl isobutyl ketone. 

Methyl m-tolyl (8), ethyl m-tolyl, methyl n-butyl and methyl n-propyl sulfoxides were obtained in 100% e.e. This method was less successful when applied to methyl phenyl sulfoxide (5% e.e.) or to methyl isobutyl and methyl ethyl sulfoxides (25% e.e.). No complexes were formed between methyl o-tolyl, methyl p-tolyl, methyl 2-butyl and methyl isopropyl sulfoxides so these compounds could not be resolved using 7. A crystal structure of the 1 1 complex formed between 7 and 8 revealed that the partners were linked by OH—OS hydrogen bonds in endless zig-zag chains23. More recently, 2-chloroethyl m-tolyl sulfoxide (9) has been resolved using 724. 

For some tertiary substrates, the rate of SnI reactions is greatly increased by the relief of B strain in the formation of the carbocation (see p. 366). Except where B strain is involved, P branching has little effect on the SnI mechanism, except that carbocations with P branching undergo rearrangements readily. Of course, isobutyl and neopentyl are primary substrates, and for this reason they react very slowly by the SnI mechanism, but not more slowly than the corresponding ethyl or propyl compounds. 

Closely related compounds, even enantiomers, may not show similar binding affinities. OBP1 specifically bound 2- H-3 -isobutyl-3-methoxypyrazine, whereas OBP2 did not a derivative compound (2-isobutyl-3-methoxy-pyrazine) was unable to displace ligands from OBP-2 (Lobel et al., 1998). 

Detectability may be a significant problem with homologous series of unsaturated compounds, particularly //-alkanes. For these compounds, refractive index detection or evaporative light-scattering, both of which are described elsewhere in the book, may be of use. Indirect photometry is a useful detection scheme for compounds that do not absorb in the UV. Acetone, methylethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, and acetophenone are added to an acetonitrile/water mobile phase, generating a negative vacancy peak when the nonchro-mophoric analyte emerges and a positive peak if the ketone is adsorbed and displaced.70 Dodecyl, tetradecyl, cetyl, and stearyl alcohols also have been derivatized with 2-(4-carboxyphenyl)-5,6-dimethylbenzimidazole and the derivatives separated on Zorbax ODS in a mobile phase of methanol and 2-propanol.71... 

Dermal Effects. Skin irritation was noted in wildlife officers at the RMA after they handled sick or dead ducks without gloves (NIOSH 1981). Although the investigators concluded that diisopropyl methylphosphonate contributed to the local effects, a number of other compounds were present. Analysis of the pond water indicated the presence of a number of organic and inorganic contaminants, including diisopropyl methylphosphonate (11.3 ppm) aldrin (0.368 ppm) dieldrin (0.0744 ppm) dicyclo-pentadiene, bicycloheptadiene, diethyl benzene, dimethyl disulfide, methyl acetate, methyl isobutyl ketone, toluene, and sodium (49,500 ppm) chloride (52,000 ppm) arsenic (1,470 ppm) potassium (180 ppm) fluoride (63 ppm) copper (2.4 ppm) and chromium (0.27 ppm). Because of the presence of numerous compounds, it is unclear whether diisopropyl methylphosphonate was related to the irritation. 

Organophosphate Ester Hydraulic Fluids. Organophosphate esters are made by condensing an alcohol (aryl or alkyl) with phosphorus oxychloride in the presence of a metal catalyst (Muir 1984) to produce trialkyl, tri(alkyl/aryl), or triaryl phosphates. For the aryl phosphates, phenol or mixtures of alkylated phenols (e.g., isobutylated phenol, a mixture of several /-butylphenols) are used as the starting alcohols to produce potentially very complex mixtures of organophosphate esters. Some phosphate esters (e.g., tricresyl and trixylyl phosphates) are made from phenolic mixtures such as cresylic acid, which is a complex mixture of many phenolic compounds. The composition of these phenols varies with the source of the cresylic acid, as does the resultant phosphate ester. The phosphate esters manufactured from alkylated phenylated phenols are expected to have less batch-to-batch variations than the cresylic acid derived phosphate esters. The differences in physical properties between different manufacturers of the same phosphate ester are expected to be larger than batch-to-batch variations within one manufacturer. 

Other compounds, such as 2,4,6-trichloroanisole (TCA), 2-isopropyl-3-methoxypyrazine and 2-isobutyl-3-methoxypyrazine, were found downstream of a pulp mill effluent, and were considered as off-flavours. These compounds are by-products of chlorination, or can be produced by actinomycetes or other biota [74]. 

Go back to the temperature-mole fraction diagram for the isopropyl alcohol-isobutyl alcohol system (Fig. 140). The composition of the vapor is always different from that of the liquid, and we can separate the two compounds. If the composition of the vapor is the same as that of the liquid, that separation is hopeless. Since we ve used the notions of an ideal gas in deriving... 

Isobutylene isoprene rubber (IIR), in tire compounding, 21 807 Isobutyl formate, physical properties, 6 292t... 

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