Neohexene synthesis

Neohexene, synthesis of, 26 939-941 Neoisomenthol, 24 512, 513 Neomenthol, 24 512, 513 Neomethymycin, 15 272 Neomycin, bacterial resistance mechanisms, 3 32t... 

FIG. 5 Schematic diagram of the process for neohexene synthesis from isobutene (a) dimerization (b) separation (c) disproportionation (d) separation. (From Ref. 19.)... 

Above we have mentioned several heterogeneous applications such as the OCT process and SHOP. Neohexene (3,3-dimethyl-1-butene), an important intermediate in the synthesis of fine chemicals, is produced from the dimer of isobutene, which consists of a mixture of 2,4,4-trimethyl-2-pentene and 2,4,4-trimethyl- 1-pentene. Cross-metathesis of the former with ethene yields the desired product. The catalyst is a mixture of W03/Si02 for metathesis and MgO for isomerisation at 370 °C and 30 bar. The isobutene is recycled to the isobutene dimerisation unit [48],... 

Further important industrial applications of olefin metathesis include the synthesis of 3,3-dimethyl-l-butene ( neohexene , intermediate for the production of musk perfume) from ethene and 2,4,4-trimethyl-2-pentene, the manufacture of a,co-dienes from ethene and cycloalkenes (reversed RCM), and the ROMP of cyclooctene and norbomene to Vestenamer and Norsorex , respectively. 

Dimethylbut-l-ene (neohexene) is an important intermediate in the synthesis of musk perfume. Its production was begun by the Phillips Petroleum Co. in 1969. Demand has steadily grown (Banks 1982). The process is based on the dimer of... 

The latest (1980) commercial application of olefin metathesis is Phillips Neohexene Process ( ). Neohexene, an intermediate in the synthesis of a perfume musk, is produced by cross-metathesis of diisobutylene with ethylene (i,e., ethylene cleavage) over a bifunctional (double-bond isomerization/metathesis) catalyst system (Figure 7) ... 

As said above, the main application of neohexene is the synthesis of musk perfume components, in two steps. The first step is the alkylation of / -cymene by neohexene and the second a reaction with acetyl chloride ... 

It is still unclear how the initiation step in alkene metathesis occurs and how the initial carbene forms. Commercial applications of metathesis include the triolefin process, in which propylene is converted to ethylene and butene, the neohexene process, in which the dimer of isobutylene, Me3CCH=CMe2, is metathesized with ethylene to give Me3CCH=CH2, an intermediate in the manufacture of synthetic musk, and a 1,5-hexadiene synthesis from 1,5-cy-clooctadiene and ethylene. Two other applications, SHOP and ROMP (Shell higher olefins process and ring-opening metathesis polymerization), are discussed in the next section. 

Dimethyl-I-butene (neohexene), an important intermediate for the synthesis of musk perfumes, is produced on a commercial scale either from diisobu-... 

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