M-Chlorostyrene

Write a structural formula for each of the following compounds (a) o Ethylanisole (b) m Chlorostyrene (c) p Nitroaniline... 

Figure 6.68 Enantioconvergent hydrolysis of m-chlorostyrene oxide using a single biocatalyst.

The enantioconvergent biohydrolysis of m-chlorostyrene oxide (Figure 6.68) in the presence of a recombinant S. tuberosum EH afforded the corresponding (JJ)-diol in a nearly quantitative yield [187]. The (S)-epoxide was attacked at the benzylic (more substituted) carbon whereas the (R)-epoxide was attacked at the terminal (less substituted) carbon. 

This procedure has been used in the preparation of other nitrostyrenes in the following yields o-nitrostyrene (40%),2 / -nitrostyrene (41%),2 and 3-nitro-4-hydroxystyrene (60%).2 A better procedure for more volatile styrenes involves simultaneous decarboxylation and codistillation with quinoline from the reaction flask. This method has been used to prepare the following styrenes o-chlorostyrene (50%),3 4 m-chlorostyrene (65%),4 -chlorostyrene (51%),4 m-bromostyrene (47%),4 o-methoxystyrene (40%),4 -methoxystyrene (76%),4 m-cyano-styrene (51%),3 and j -formylstyrene (52%).9... 

In an attempt to prepare the stilbene (1), the dihydropyridine (2) was pyrolysed at 180°C at 0.1mm. The products obtained, however, were m-chlorostyrene (82%) and 2,4,6-triphenyl-pyridine. 

TABLE 6.1.2.13.1 Reported vapor pressures of m-chlorostyrene at various temperatures ... 

Much activity continues to be centered around the preparation of enantioenriched epoxides using chiral Co(III)-, Mn(III)- and Cr(III)-salen complexes, particularly in the area of innovative methods. A recent brief review <02CC919> focuses on the synthesis, structural features, and catalytic applications of Cr(III)-salen complexes. In an illustrative example, Jacobsen and coworkers <02JA1307> have applied a highly efficient hydrolytic kinetic resolution to a variety of terminal epoxides using the commercially available chiral salen-Co(III) complex 1. For example, treatment of racemic m-chlorostyrene oxide (2) with 0.8 mol% of catalyst 1 in the presence of water (0.55 equiv) led to the recovery of practically enantiopure (> 99% ee) material in 40% yield (maximum theoretical yield = 50%). This method appears to be effective for a variety of terminal epoxides, and the catalyst suffered no loss of activity after six cycles. 

Effective separation of m-chlorostyrene from > -chloro-phenylmethylcarbinol is possible with the short column specified. If a fractionating colunan is not used, lower conversions result and the crude product contains w-chlorophenyhnethylcarbinol, which can be separated by fractional distillation and used in a subsequent preparation. 

After the formulas for rate constants are known, any diad sequence distribution can be calculated in the copolymer with an unknown composition from the dimer yields. The procedure has been studied for several copolymers including poly(acrylonitrile-co-m-chlorostyrene) [17], poly(styrene-co-glycidyl methacrylate) [19], poly(acrylonitrile-co-p-chlorostyrene) [17], poly(styrene-co-methacrylate) [20], poly(styrene-co-p-chlorostyrene) [18], and for other copolymers [14, 21-29]. 

One of these studies evaluates the sequence distribution of dyads in styrene-m-chlorostyrene copolymer and in styrene-p-chlorostyrene copolymer [17]. The results are obtained using data from pyrolysis performed at 550° C and FID detection. In a similar study, the sequence distribution of dyads was evaluated for poly(acrylonitrile-co-m-chlorostyrene) and for poly(acrylonitrile-co-p-chlorostyrene) [18] (see also Section 4.3). 

Overberger and Saunders prepared m-chlorostyrene (6) by charging a flask equipped with a dropping funnel and a short fractionating column with 12.5 g. of fused, powdered KHSO4 and 0.05 g. of p-t-butylphenol (as antioxidant), heating the mixture in a bath at 220-230° at a pressure of 125 mm., and adding 145 g. of... 

COP = copolymer of ethylacrylate and methylmethacrylate CMC = poly(glycidylmethacrylate-co-m-chlorostyrene) P( ETMA-co-MM A) = poly (ethylthiomethacrylate-co-methylmethacrylate) PCMS = poly(m-chloromethylstyrene) PVMS = poly(methylvinyl siloxane) ... 

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