Ethylstyrene isomers

FIGURE 5.5 Potential components of commerical divinylbenzene, DVB isomers, ethylstyrene isomers, diethylbenzene isomers, styrene, and ethylbenzene. 

Because 100% DVB is not available commercially, one has to choose either 56% DVB or 80% DVB for the preparation of GPC/SEC gels. The potential components of commercial divinylbenzene are shown in Fig. 5.5. The composition of commercial 56% DVB consists of 56% DVB isomers and 44% ethylstyr-ene and diethylbenzene isomers. The diethylbenzene is nonreactive, but the ethylstyrene acts as styrene in the formulation and tends to produce softer, more swellable GPC gels. Therefore, it is not necessary to actually add styrene to the formulation to produce a ST-DVB gel. Because 80% DVB has only 20% ethylstyrene and diethylbenzene isomers the GPC/SEC gel produced using it would be more rigid and less swellable. 

Like a-melhyislyrene (2-phenyl-1-propene) the isomeric alkenes a-ethylstyrene (2-phenyl-1-butene), (Z)- and ( )-2-phenyl-2-bulene are hydrocarboxylated under similar conditions19. However, different optical rotations are observed for methyl 3-phenylbutanoate, the common reaction product (values between 8.1 to 10.5). This supports the assumption of individual induction steps for each isomer and excludes the isomerized substrate being released from the complex. 

Benzene, ethenylethyl- EINECS 248-846-1 Ethylstyrene Styrene, ar-ethyl-. Mixture of 0, m and p-isomers. 

In the pyrograms of Cl-MST-DBV copolymers (Figure 1.5), styrene monomer, dimer and trimer characteristics of styrene sequences are commonly observed, and their peak intensities decrease as the chlorine content increases. Additionally, decreases in the peak intensities of the meta and para isomers of DVB and ethylstyrene as a function of chlorine content indicate that Friedel-Crafts chloromethylation also occurs in DVB and ethylstyrene moieties in the copolymer. The greater decreases in the peak intensities of the meta isomers than those of the para isomers suggest that the Friedel-Crafts chloromethylation occurs more selectively on the meta isomers of DVB and ethyl styrene units. p-Methylstyrene and its dimer characteristic of chloromethylated styrene units are observed in the pyrograms of chloromethylated samples since the Friedel-Crafts chloromethylation occurs mostly on the para position of the styrene units (Figure 1.6). 

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