Codimer

Table 4. Effect of Cyclopentadiene—Acyclic Diene Codimers on DCPD-Based Thermal Polymerizations ...

The purity of a dicyclopentadiene stream may be expressed in terms of DCPD itself or in terms of available CPD monomer. Both analyses are deterrnined by gas chromatography (gc). The first analysis is capillary gc on a nonpolar column. The data from the analysis can be used to calculate the available CPD, assuming that all the DCPD and CPD codimers crack completely. In the second analysis the sample is charged to the gc equipment under temperature conditions (injection port 400°C) that cause essentially complete reaction of the dimers to monomers. 

Obtaining high purity (>99%) CPD, or alternatively high purity DCPD, from lower purity (75—85%) DCPD is not readily accompHshed ia high yield by straight fractional distillation. The main difficulty ia this purification of DCPD is the presence of codimers of C and C acycHc dienes with CPD,... 

Table 4. Estimated Boiling Points of DCPD Codimer Cycloolefins ...

When high purity isobutylene is not required, the acid extract from the rich stage may be heated for a few minutes to 250-300°F, and then quickly cooled. Under these conditions the isobutylene dimerizes to form largely 2,4,4, trimethyl pentene-1. This is known as the dimer process and may be used to concentrate i-butenes for dehydrogenation feed, the isobutylene dimer being added to the motor gasoline pool. Trimers, as well as codimers with normal butenes are also produced. 

A Cj to Cg cracked naphtha cut is heated imder pressure in a soaking drum. Dimers and codimers of cyclopentadiene, methylcyciopentadiene, and isoprone are formed. This is followed by distillation, leaving a dimer concentrate bottoms. 

USA Atrohist (Medeva)-comb. Codimal (Schwarz)-comb. 

The selectivity problem is particularly important in the dimerization of two different olefins when, in addition to the required codimers, a mixture of the two possible homodimers may be produced. 

There can be little doubt that the active species involved in most or even all of the various combinations described in Section II is HNi(L)Y (see below), because the different catalysts prepared by activating the nickel with Lewis acids have been shown to produce, under comparable conditions, dimers and codimers which have not only identical structures but identical compositions. On modification of these catalysts by phosphines, the composition of dimers and codimers changes in a characteristic manner independent of both the method of preparation and the nickel compound (2, 4, 7, 16, 17, 26, 29, 42, 47, 76). Similar catalysts are formed when organometallic or zero-valent nickel complexes are activated with strong Lewis acids other than aluminum halides or alkylaluminum halides, e.g., BFS. 

A scheme which was considered by Hougen and Watson (18) and is slightly more complicated is the hydrogenation of isooctene codimer. This illustrates a reaction with a large number of cycles compared with the number of intermediates. 

A supported nickel catalyst was used to study the reaction in which mixed isooctenes, commercially known as codimer, are hydrogenated in the vapor phase to the corresponding isooctanes. Neglecting isomerization, the following steps are assumed to occur ... 

The reactor inlet temperature is about 400° F. for nonselective operation or about 350° to 370° F. for codimer production from butenes. The temperature rise is of the order of 20° to 50° F. 

Substituted 2-(/J-oxoalkyl)tetrahydrofurans have been prepared in acceptable yields by a one-step aldol-type reaction of allyl ketones and 4-methyl-l-phenyl-4-penten-l-one, catalyzed by a rhodium(I) complex-tin(II) chloride mixture (equation 180)652. This type of catalyst mixture has also been used for both linear653 and cyclic654 codimers in a similar fashion. 

There is yet another linear isomer CCNN (4d). This can be conceived as a codimer of C2 and N2 monomers, held together by a donor-acceptor bond between the 3ag LUMO of C2 and the doubly occupied 3og of N2. The central... 

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