1 -phenyl-3-methyl-1,2-butadiene

If the reaction is allowed to become warm, substantial protodesilylation of the product takes place to give 3-methyl-1 -phenyl-1,3-butadiene. The aqueous workup should be carried out rapidly to minimize this side reaction. The use of hydrochloric acid has particular advantage since all of the salts dissolve facilitating the extractions. 

Gas chromatographic analysis (0.53-mm id x 10 m poly (dimethyl silicone) fused silica column, temperature programmed from 140°C to 220°C) indicates that this product is 98% pure, with <1% 3-methyl-1-phenyl-1,3-butadiene and 1-2% of a less volatile, unidentified component. The checkers could obtain a very pure product by normal vacuum distillation. They found the impurities to be higher boiling compounds. 

Case I. First of all, we systematically introduced perturbation at coupled ff-systems (e.g. ethylene, butadiene, hexatriene and combinations of them) by substituting hydrogen for functional groups (classified by K. N. Houk as C-, Z- and X-substituents ), especially by methyl phenyl and carboxylic ester groups. We have so far introduced perturbations in the rr-system by replacing carbon atoms by heteroatoms (N and 0) in the rr-system skeleton. 

The evidence that ,Z-isomerization of 92-95 proceeds by Si=Si bond rotation and not a mechanism involving silylene intermediates, produced by cleavage of the Si=Si bond followed by recombination, rests upon the fact that no trapping products consistent with the intermediacy of the corresponding diarylsilylenes could be detected upon heating the disilenes in the presence of known silylene traps such as methanol, triethylsilane or 2,3-dimethyl-l,3-butadiene. In fact, one tetraaryldisilene has been shown to isomerize by this mechanism, the 1,2-dimesityl-l,2-bis(2,4,6-tris[bis(trimethylsilyl)methyl]phenyl derivatives (E)- and (Z)-97a (equation 70)142,143. Arrhenius parameters for the thermal dissociation of (E)- and (Z)-97a to diarylsilylene 98 are listed in equation 70. 

It is apparent from Table 6 that methyl and methoxy substituents enhance the reactivity of butadiene and anthracene, while chlorine atoms decrease that of butadiene and cyclopentadiene, towards electrophilic dienophiles. Phenyl substituents have very different effects in positions I and 2 [columns (i) and (iv)] here the substituent is large enough to exert a marked steric influence on the cisoid transo/c/equilibrium of the diene, so that the conformation of 2-phenyl-butadiene is favoured, and therefore the overall reactivity of 2-phenyl-butadiene is enhanced, while trans-1 -phenyl-butadiene is little affected. Cyclic unsubstituted dienes are more reactive than butadiene however, the difference between cyclopentadiene and cyclohexadiene is enormous the high reactivity of the former must be in part attributed to factors other than the cisoid conformation. 

Terpolymer of vinyl pyridine, styrene and butadiene (ASTM elastomer) Poly(methyl phenyl siloxane) (ASTM)... 

Little has been published on techniques for achieving the homopolymerization of mono or disubstituted MA monomers (see Chapter 3). Thamm and Hensinger recently showed that y irradiation of dichloromaleic anhydride (DCMA) in benzene produced a polymer as the main product. The yield and molecular weight of the polymer increased with radiation dose. The polymer backbone contained chlorophenylsuccinic anhydride residues. It was shown that chlorophenylmaleic anhydride was produced during the reaction. Under the same conditions, dimethylmaleic anhydride (DMMA) failed to polymerize with free-radical, ionic, and UV initiation with sensitizers.Presumably, techniques may be found for the homopolymerization of chloro or phenyl-maleic anhydride. Chloromaleic anhydride (CMA) reacts with methyl radicals more readily than MA and much more readily than DCMA. " This, coupled with halogen activation and ring coplanarity, should allow CMA to be homopolymerized. It is known that CMA will copolymerize with styrene, methyl methacrylate, butadiene, cyanoacrylates, and other olefins. 

Phenyl-1,4-hcxadicnc (122) is obtained as a major product by the codimerization of butadiene and styrene in the presence of a Lewis acid[110]. Pd(0)-catalyzed addition reaction of butadiene and aiiene (1 2) proceeds at 120 C to give a 3 1 mixture of trans- and c -2-methyl-3-methylene-l,5.7-octatriene (123)[lll]. 

The reaction of crotonaldehyde and methyl vinyl ketone with thiophenol in the presence of anhydrous hydrogen chloride effects conjugate addition of thiophenol as well as acetal formation. The resulting j3-phenylthio thioacetals are converted to 1-phenylthio-and 2-phenylthio-1,3-butadiene, respectively, upon reaction with 2 equivalents of copper(I) trifluoromethanesulfonate (Table I). The copper(I)-induced heterolysis of carbon-sulfur bonds has also been used to effect pinacol-type rearrangements of bis(phenyl-thio)methyl carbinols. Thus the addition of bis(phenyl-thio)methyllithium to ketones and aldehydes followed by copper(I)-induced rearrangement results in a one-carbon ring expansion or chain-insertion transformation which gives a-phenylthio ketones. Monothioketals of 1,4-diketones are cyclized to 2,5-disubstituted furans by the action of copper(I) trifluoromethanesulfonate. ... 

Benzyl frans-1,3-butadiene-1-carbamate 1,3-Butadienecarbamic acid, benzyl ester (8) Carbamic acid, 1,3-butadienyl-, phenyl-methyl ester (9) ( —)... 

The amination of styrene, however, led to two products (1-phenyl-1-ethylamine and 2-phenyl-l-ethylamine) in a 1 3 ratio [113], indicating that the hydrozirconation was not completely regioselective [114,115]. Since it is well known that hydrozirconation of trisubsti-tuted alkenes places zirconium at the least hindered carbon of the chain by a process involving zirconium migration, this class of alkenes was not investigated [5,116], On the other hand, hydrozirconation/amination of 3-methyl-l,2-butadiene gave an allylic amine. Reaction of the latter could either occur at the terminal carbon or proceed with... 

The polymer types shown are linear polystyrene, two types of branched polystyrene (methyl methacrylate), poly (vinyl chloride), poly butadiene poly (phenyl soiloxane), and two types of copolymer. 

The kinetic behavior of 1,3-dienes has also been investigated in as much detail as that of alkenes52. Some data are collected in Table 4. The effect of a vinyl group on the reactivity of carbon-carbon double bonds toward p-methoxydiphenylcarbenium ion has been compared with that of methyl and phenyl substituents (Table 5). Whereas butadiene reacted 21 times faster than propene, the reactivity of isoprene was significantly lower... 

Figure 4 in Scheme 2.3-4 demonstrates that when using a triphenylphosphane-modified Ni-catalyst, butadiene reacts with 2-butyne to form a 2 1-adduct whereas with methyl 2-butynoate, a 1 2 co-oligomer is obtained. Butadiene and phenyl-acetylene also form 1 2 products As we may have shown, a change from X- to C- or Z-type substituents in the co-substrates alters the ratio from 2 1 to 1 2 in a synthon coupling reaction. 

E. [l,4-BIS(METHOXYCARBONYL)-2-METHYL-3-PHENYL-l,3-BUTADIENE-1,4-DIYL]-(ti5-CYCLOPENTADIENYL)-(TRIPHENYLPHOSPHINE) COBALT AND [1,3-BIS(METHOX YCARBONYL)-2-METH YL-4-PHENYL-1,3-BUT ADIENE-1,4-DI YL]-(q 5-C Y CLOPENT ADIENYL)-(TRIPHENYLPHOSPHINE)COBALTt... 

Bis(methoxycarbonyl)-2-methyl-3-phenyl-l, 3-butadiene-1,4-diyl]cobalt=2,5-dicarbo-methoxy-3-phenyl-4-methylcobaltacyclopentadiene. 

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