Cycl ization reaction

These reactions can also be run in benzene, which is preferable in cases where transfer of hydrogen to the vinyl radical is competitive with cycl izat ion. 

Coversion of HgC=CH(CHg) M to CHg(CHg)2CHCHgM is faster for M=Lithan for R=MgX but is still 10 -10 times slower than cycl-ization of CHg=CH(CHg) . The mere observation of cyclopentylmethyl products in reactions of CHg=CH(CHg) X is not sufficient evidence for a radical process. However the reaction of Bu Li with CH2=CH(CHg)gCHRBr (R-H or Me) at low T does produce stable cyclized and uncyclized organolitbiums as well as cyclized hydro-... 

Decolorization and Finishing. Decolor-ization is sometimes required for certain applications, mostly as an aesthetic preference. It is always desirable to solve these issues upstream. For example, color can be minimized by choice of fermentation medium components and control of the sterilization cycle so as to lessen the Maillard reactions between nitrogen and sugars and carameliza-tion. Color can also be reduced by treatment with activated carbon, use of antioxidants, and by diafiltration with membranes. Carbon-impregnated filter pads can be used to combine polish filtration with a decolorization step. 

So far we have proposed a refined catalytic reaction cycle for the co-oUgomer-ization process and have furthermore analyzed the catalytic structure-reactivity relationships for the regulation of the Cm-olefin product selectivity. This, together with our recent theoretical-mechanistic exploration of the [Ni ]-catalyzed 1,3-butadiene cyclooUgomerization affording Cij-cycloolefins [4c,d], enables us now to undertake a comparison of crucial mechanistic aspects of the two reactions. Furthermore, the interplay of the two alternative reaction channels for co-oligomerization and cyclooligomerization wiU be analyzed (Scheme 4). 

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