Diisopropyl isomerization

An autoclave was charged with the step 2 product mixture (91.0 g), 5 wt% ruthenium on carbon (9.1 g), and 300 ml diisopropyl ether and then sealed and heated to 100°C. Hydrogen was then introduced and the reaction continued for 14 hours at 0.7-1.0 mPa. The mixture was then filtered by Celite , concentrated, and 82.7 g of product isolated as white crystals after recrystallization. Analysis of the mixture indicated it consisted of four isomers (Isomers 1-4) in an isomeric ratio of Isomer 1 (preferred) Isomer 2 Isomer 3 Isomer 4 of 37 36 17 10, respectively. 

Napththa Isomerization. The only commercial isomerization of light naphtha was carried out in two plants employing the isomate process developed by the Standard Oil Co. (Indiana) (20). In this process, a feed containing normal pentane and low octane number hexanes is converted to isopentane and to hexanes of higher octane number. Pentanes and hexanes in any ratio may be processed. By recycle of selected fractions of the product, concentrates of isopentane or of neohexane and diisopropyl can be obtained as the ultimate products. 

The (E) and (Z) forms of the vinylboron compounds 278 and 279 can be prepared by hydroboration of alkynes and haloalkynes, and their reactions with the (E)- or (Z)-vinyl iodides or bromides 280 and 281 proceed without isomerization the four possible isomers 282-285 can be prepared in high purity. However, for the efficient preparation of the (Z,Z)-dienes 287, the diisopropyl ester of (Z)-alkenylboronic acid 286 should be used. Other boron compounds give poor yields... 

Configuration of cis-trans Isomeric Ozonides. In symmetrically di-substituted trioxolanes, the cis isomer is a meso and the trans isomer is a racemic form. Therefore, resolution into antipodes makes it possible to determine the configuration. In 1966, Loan, Murray, and Story (4) were able to obtain an optically active form of one of the diisopropyl-trioxolanes, proving it to be the trans isomer. Their method—partial decomposition of the ozonide by brucine—could not be applied to the stilbene ozonides. 

The organozinc reagent derived from 3-bromo-l-butyne which has the allenic structure (XLII) affords a mixture of three isomeric alcohols upon reaction with diisopropyl ketone, indicating the strong tendency of rearrangement in the systems (171). The proportion of allenic alcohol... 

The beauty of this reaction lies in the fact that nearly all the facts needed to elucidate the mechanism are, in one way or another, in the products. Although the formation of II might seem somewhat tantalizing at first, a second glance will reveal that simply isomerization of I will suffice to account for it. A rather unusual isomerization, however, because activation of the a carbon of the ester as a nucleophile and introduction of foimaldehyde (from where ) at this carbon need justification. The first argument may be reformulated as the formation of an ester enolate, which is made possible by the advent of lithium amide superbases such as lithium diisopropyl amide (LDA) in aprotic tetrahydrofuran (THF)-hexamethyl-phosphoramide (HMPA) solvent mixtures. The participation of an ester enolate is emphasized by the formation of condensed diester IV. 

Allylboronate 196 is prepared from the reaction of allyl magnesium bromide with trimethylborate followed by esterification with diisopropyl tartrate (DIPT) in the presence of MgS04 (Eq. (11.13)) [116]. In analogous fashion, the (E)- and (Z)-crotylboronates 219 and 213 are prepared [139] in high isomeric purity (>98%) from ( )- and (Z)-2-butene by way of the (E)- and (Z)-crotylpotassium... 

Similarly, treatment of diisopropyl 2-chloro-2-propenylphosphonate with 10% aqueous methanolic NajCOj at room temperature induces facile dehydrochlorination with subsequent double-bond isomerization to produce diisopropyl 1-propynylphosphonate in essentially quantitative yields. ... 

An alternative procedure for the synthesis of 1-propynylphosphonic ester uses the Michaelis-Arbuzov reaction of 2,3-dichloro-l-propene with triisopropyl phosphite to produce almost quantitatively diisopropyl 2-chloroallylphosphonate. On treatment with aqueous methanoUc NagCOj solution at room temperature, it is converted into diisopropyl 1-propynylphosphonate by a dehydrochlorination-isomerization sequence (Scheme 4.25). ... 

The aspect of the chemistry of the organophosphorodithioate salts most meaningful for their additive action involves their reaction with metals. Luther and Sinha [51] did not find any significant influence of the substrate metals on the thermal decomposition of isomeric zinc dibutyl phosphorodithioates over iron or silver. On the other hand, careful studies by Baumgarten [53] demonstrate the chemisorption of dialkylphosphorodithioate salts on metal, either powder or as evaporated film. Of particular interest are the findings for zinc diisopropyl phos-phorodithioate triply tagged with the radioactive elements Zn, and... 

The combined liquid effluent from the fluidized-bed run was collected, and a complete analysis was made. The data are shown in Table V. The extensive isomerization taking place is of some interest all of the C6 paraffins except diisopropyl are present in the effluent, along with cyclohexane-methylcyclopentane, MCH-dimethylcyclopentane, etc. Nickel is, of course, known to have isomerizing activity, but in addition the catalyst may be functioning as a dual-function isomerization catalyst. 

Dihydroperoxides are formed in the oxidation of diethyl and diisopropyl ethers, together with the hydroperoxides [203,283,285]. Their production can be explained by isomerization of peroxy radicals. 

Temperature and solvent polarity are responsible for the skeletal isomerism observed in the cluster [Os3(CO)io(Pr -DAB)] (Pr -DAB = 1,4-diisopropyl-1,4-diaza-1,3-butadiene). Thus the 48e triangular cluster [Os3(CO)io( Pr -DAB)] (1) is converted, by heating under reflux in -hexane, to the 50e skeletal isomer with an open metal chain (2). In the former compound the Pr -DAB ligand contributes four electrons while in the latter it contributes six. 

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