3,5-DImethyl-4- styrene preparation

C17H24O, Mr 244.38, mp 35 °C, is a synthetic musk fragrance. It is prepared by Friedel-Crafts acetylation of 1,1,2,3,3,5-hexamethylindane, which can be obtained as a 70 30 mixture with l,l,3,5-tetramethyl-3-ethylindane by reacting a,p-dimethyl-styrene with amylenes or 2-methyl-2-butanol in a mixture of acetic acid and concentrated sulfuric acid [155] ... 

The open transition state—-hybridized carbocations— has low stereoselectivity, thus mostly atactic polymers are formed (94). At the same time, reportedly the very first synthetic stereoregular polymer was an isotactic poly(isobutyl vinyl ether) prepared by carbocationic polymerization initiated with BF3/0(C2115)2 at -78°C (95). Other examples of stereoregular crystalline polymers synthesized by homogeneous and heterogeneous carbocationic polymerization are polymers of vinyl ether derivatives, and 2,5-dimethyl styrene or a-methylstyrene (95-100). Stereoregular vinyl ether polymers have also been synthesized using... 

The basic patent (US Patent 3256219) indicates that the system is viable with conventional resins although special grades have been developed that are said to be particularly suitable. One example in the patent recommends the use of a polyester prepared using a maleic acid, phthalic acid and propylene glycol ratio of 2 1 33 and with an acid value of 40. To 500g of such a resin are added 10g of benzoyl peroxide and 167 g of styrene. Water 600 g is then stirred in at 5-10°C until a white creamy water-in-oil emulsion is obtained. A solution of 0.8 g of dimethyl-p-toluidine in lOOg of styrene is stirred into the emulsion and the resin is cast between plates and cured at 50°C. 

Kondo maintained his interest in this area, and with his collaborators [62] he recently made detailed investigations on the polymerization and preparation of methyl-4-vinylphenyl-sulfonium bis-(methoxycarbonyl) meth-ylide (Scheme 27) as a new kind of stable vinyl monomer containing the sulfonium ylide structure. It was prepared by heating a solution of 4-methylthiostyrene, dimethyl-diazomalonate, and /-butyl catechol in chlorobenzene at 90°C for 10 h in the presence of anhydride cupric sulfate, and Scheme 27 was polymerized by using a, a -azobisi-sobutyronitrile (AIBN) as the initiator and dimethylsulf-oxide as the solvent at 60°C. The structure of the polymer was confirmed by IR and NMR spectra and elemental analysis. In addition, this monomeric ylide was copolymerized with vinyl monomers such as methyl methacrylate (MMA) and styrene. 

Homochiral pyridyl, bipyridyl, and phosphino derivatives of 2,2-dimethyl-1,3-dioxolane (113)-(115) were prepared from T-(+)-tartrate. These compounds were assessed in metal-catalyzed asymmetric hydroformylation of styrene enantioselectivity was generally low.342... 

Organometallic usage is shown in the preparation of titanium- or vanadium-containing catalysts for the polymerization of styrene or butadiene by the reaction of dimethyl sulfate with the metal chloride (145). Free-radical activity is proposed for the quaternary product from dimethylaniline and dimethyl sulfate and for the product from l,l,4,4-tetramethyl-2-tetrazene and dimethyl sulfate (146,147). 

A poly(methyl methacrylate-fe-styrene-6-methyl methacrylate) sample with an approximately equal content of both monomeric units was fractionated by preparative SEC into 34 fractions. The SEC eluent was dimethyl formamide and the starting... 

In addition to providing fully alkyl/aryl-substituted polyphosphazenes, the versatility of the process in Figure 2 has allowed the preparation of various functionalized polymers and copolymers. Thus the monomer (10) can be derivatized via deprotonation—substitution, when aP-methyl (or P—CH2—) group is present, to provide new phosphoranimines some of which, in turn, serve as precursors to new polymers (64). In the same vein, polymers containing a P—CH3 group, for example, poly(methylphenylphosphazene), can also be derivatized by deprotonation—substitution reactions without chain scission. This has produced a number of functionalized polymers (64,71—73), including water-soluble carboxylate salts (11), as well as graft copolymers with styrene (74) and with dimethyl siloxane (12) (75). 

SYNTHESIS A well-stirred solution of 1.77 g 2,5-dimethoxy-B-nitro-4-(n-propylthio)styrene (see under 2C-T-7 for its preparation) in 20 mL anhydrous THF was placed in an He atmosphere and treated with 1.5 mL of 10 M borane-dimethyl sulfide complex. This was followed by the addition of 0.2 g sodium borohydride, and the stirring was continued at room temperature for a week. The volatiles were removed under vacuum, and the residue was treated with 20 mL dilute HC1 and... 

The most common methods for the preparation of 1-benzoselenophene and its analogs involve the annulation of the selenophene ring onto a benzene substrate. Early works, such as reaction of selenium with phenylacetylene or the reaction of selenium dioxide with styrene, gave low yields but more recently elaborated procedures, e.g., gas-phase reaction of cinnamaldehyde with dimethyl diselenide at 630 °C, give 1-benzoselenophene in high yield [131, 132],... 

Rosatzin et al. copolymerised V,W-dimethyl-V,V -bis(4-vinylphenyl)-3-oxapen-tanediamide (a metal ionophore), divinylbenzene and styrene in a chloroform solution in the presence of Ca(ll) or Mg(II) [10]. The Ca(II) ionophore resin is illustrated in Scheme 9.4. The metal ion added to the matrix mixture, was expected to act as a template for the ionophore during the polymerisation. The resulting polymers were analysed for their ability to extract ions from aqueous methanol. The polymers prepared against Ca(II) and Mg(II) were found to bind Ca(II) with 6- and 1.7-times lower dissociation constants, respectively, when... 

BBN-H is readily prepared (Section 3.10.2.1, equation 8) and is commercially available. It shows considerable stability, even in air for limited periods, and is therefore a very convenient hydroborating agent.Unlike di-primary-alkylboranes it is not prone to disproportionation, but it is substantially less hindered than other di-5-alkylboranes such as dicyclohexylborane and disiamylborane. Thus, it hydroborates hindered alkenes such as 2,3-dimethyl-2-butene slowly. It is less sensitive to steric factors and more sensitive to electronic factors than disiamylborane. Thus, it shows relatively little ability to discriminate between ( )/(Z) pairs but readily discriminates between 4-methoxystyrene and 4-(trifluoro-methyl)styrene. ... 

Polymers and copolymers were laboratory-prepared samples. Samples W4 and W7 of the diblock copolymer AB poly(styrene-fo-tetramethylene oxide) (PS—PT) were synthesized by producing a polystyrene prepolymer whose terminal group was transformed to a macroinitiator for the polymerization of THF. Samples B13 and B16 of the diblock copolymer AB poly[styrene-h-(dimethyl siloxane)] (PS-PDMS) were prepared by sequential anionic polymerization. Samples of statistical copolymers of styrene and n-butyl methacrylate (PSBMA) were produced by radical copolymerization. Details of synthetic and characterization methods have been reported elsewhere (15, 17-19). 

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