Of methylstyrene

The initial series of major tranquilizers consists of alkylated derivatives of 4-aryl-4-hydroxypiperidines. Construction of this ring system is accomplished by a set of rather unusual reactions. Condensation of methylstyrenes with formaldehyde and ammonium chloride afford the corresponding hexahydro-1,3-oxazines (119). Heating these oxazines in the presence of acid leads to rearrangement with loss of water to the tetrahydropyridines. Scheme 1 shows a possible reaction pathway for these transformations. Addition of hydrogen bromide affords the expected 4-bromo compound (121). This last is easily displaced by water to lead to the desired alcohol (122) The side chain (123) is obtained by Friedel-Crafts acylation of p-fluorobenzene with 4-chloro-butyryl chloride. Alkylation of the appropriate arylpiperidinol with 123 affords the desired butyrophenone derivative. Thus,... 

Scheme 2 Anodic methoxylation of / -methylstyrene without and with an amine radical cation as mediator.

Other systems for which the results cannot be explained by energy transfer include the ketone sensitized isomerization of / -methylstyrene, 1,2-dichloro-ethylene and 2-butene studied by Caldwell,147,148 deuterium exchange between acetone-d8 and tetramethylethylene reported by Japar, Pomerantz, and Abrahamson,149 and the acetone sensitized isomerization of 1-methoxy-l-butene examined by Turro and Wriede.71... 

In contrast, the intermediate radical 91 was successfully used for AMI calculations and molecular dynamics simulations (AMBER) in order to predict the P450cam catalyzed epoxidation of / -methylstyrene 97 [72], Using the... 

A study of the intramolecular alkoxymercuration of ( )-5-arylpent-4-en-l-ols (70) has indicated that the regioselectivity is closely related to the Hammett constants of the para-substituents on the benzene ring. Large solvent effects on the regioselectivity were also observed (Scheme 17 and Tables 2 and 3). By contrast, the related oxymercuration of -methylstyrene is 100% a-sclcctivc. This comparison shows that the regioselectivity of the intermolecular reaction is controlled by electronic factors, whereas the cyclization is governed by a delicate balance of steric and electronic effects.65... 

O Driscoll and Gasparro also studied the copolymerization by free radicals of -methylstyrene (M2) with either styrene or acrylonitrile as Mi and found excellent agreement with Case II. They also showed that the limiting composition to be expected as the mole fraction of Mi in the feed approached zero was accurately given by (12) ... 

Table I. Relative Rate Constants for the Ozonolysis of -Methylstyrene (1) with Respect to Styrene (2)...

Alkyladon t es place in the vapor phase, in the presence of a gaseous eminent (nitrogen or hydrogen) around 475 C, at adiabatic reactors, with catalyst, around 450 to 500, and in the presence of steam. The blend of methylstyrenes currently commerdaitzed by Dow results from the liquid phase alkylation of toluene with aliuninom diloride. 

The monooxygenation of methylstyrene (PhCH=CHMe) to form the epoxide (Table 9) appears to involve an O-atom transfer from the end-on configuration (13) of the Fe (ROOH) + complex (eqnation 83). 

In a more conventional example Pt/ZSM-5 is used to induce reactant (size exclusion) selectivity in the hydrogenation of substituted aromatic molecules. Over Pt/ZSM-5 the rate of styrene conversion is at least 25 times higher than that of methylstyrene, while over Pt/Al Oj similar rates of hydrogenation were observed for both these compounds. 

The acid-catalyzed hydrolysis of -methylstyrene oxide (38a) in azide solutions has also been studied, but the yields of azido alcohols are only very slightly greater than the yields predicted if all of the azido alcohol is formed from the bimolecular (fcN) pathway.41 For example, in water containing 0.025 M azide ion, pH 5.75, the observed yield of azido alcohol from 38a is 22%. The calculated yield from the bimolecular reaction is 19%. This yield is very close, perhaps within experimental error, to that expected from only the bimolecular pathway (kN). If it is assumed that 3% of azido alcohol is actually from trapping of the intermediate carbocation 39a with azide ion, then a lower limit of 3 x 109 s 1 can be estimated for ks. This value is fortuitously close the value of ks estimated for reaction of l-(p-methylphenyl)ethyl carbocation with 50 50 TFE/H20 (4 x 109 s 1), and is most likely an underestimate. 

Table 7 Stereochemistry of dibromides in the bromination of -methylstyrenes in methylenechloride rate-stereoselectivity relationship. ...

The polymerization of of-methylstyrene has been experimentally studied by Greer and coworkers [79]. Poly(of-methylstyrene) is a fully flexible linear polymer chain... 

For asymmetric epoxidation of methylstyrene, dehydronaphthalene, and meta-chlorobenzoic acid in the presence of A-methylmorpholine oxide, Reger and Janda synthesized manganese complexes 33 with the salen ligand bound to the methyl ether of poly(ethylene oxide) [69]. 

A mixture of -methylstyrene and 2-phenethyl bromide added to Li in tetrahydro-furan, and the product isolated after 4hrs. at 24-35° 3,6-dimehtyl-l,3,6,8-... 

Synonyms Benzene, ethenylmethyl-, polymer with (1 -methylethenyl) benzene oc-Methylstyrene-vinyltoluene copolymer Definition Polymer of methylstyrene and vinyltoluene monomers (molar ratio 1 oc-methylstyrene to 3 vinyltoluene)... 

NFPA Health 2, Flammability 3, Reactivity 0 Storage Store in closed container in well-ventilated area away from heat, sparks, flames Uses Solvent for cellulose acetate in textile printing and dyeing mfg. of methylstyrene constituent of asphalt and naphtha Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, ChevronPhillips http //www.cpchem.com-, Fluka http //www.sigma-aldrich.com. Sigma... 

Mobil PMS is a new styrenlc monomer which is composed of 97% para-methylstyrene and 3% meta isomer (0% ortho). It is a different mixture of methylstyrene Isomers than commercially available vlnyltoluene, which contains approximately 35% para and 65% meta Isomers. It is important to compare the processes and properties for PMS and vlnyltoluene in order to understand the significance of the new material. A summary of the typical properties of styrene, vlnyltoluene and PMS is shown in Table 1. PMS and vlnyltoluene have higher boiling points and significantly lower vapor pressure than styrene, which reduces the inhalation exposure in the work environment and decreases the potential fire hazard. 

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