Carbo styrenes

Acyl halides are intermediates of the carbonylations of alkenes and organic-halides. Decarbonylation of acyl halides as a reversible process of the carbo-nylation is possible with Pd catalyst. The decarbonylation of aliphatic acid chlorides proceeds with Pd(0) catalyst, such as Pd on carbon or PdC, at around 200 °C[109,753]. The product is a mixture of isomeric internal alkenes. For example, when decanoyl chloride is heated with PdCF at 200 C in a distillation flask, rapid evolution of CO and HCl stops after I h, during which time a mixture of nonene isomers was distilled off in a high yield. The decarbonylation of phenylpropionyl chloride (883) affords styrene (53%). In addition, l,5-diphenyl-l-penten-3-one (884) is obtained as a byproduct (10%). formed by the insertion of styrene into the acyl chloride. Formation of the latter supports the formation of acylpalladium species as an intermediate of the decarbonylation. Decarbonylation of the benzoyl chloride 885 can be carried out in good yields at 360 with Pd on carbon as a catalyst, yielding the aryl chloride 886[754]. 

Similarly mixed hydrodimers of type 151 were obtained with styrene and (C6H5)3P(CH2)nCN (n=3,4) 455( Analogously the benzyl, cyanomethyl or carbo-... 

The fact that tertiary alcohols can dehydrate intramolecularly with an acid as a catalyst to form olefins has been employed in the design of negative resists based on polarity switch. A good example is poly[4-(2-hydroxy-2-propyl)styrene], which undergoes acid-catalyzed dehydration to yield a stable tertiary benzylic carbo-cation, which subsequently eliminates a (3-proton to form a pendant olefinic structure (Scheme 6.18). " This intramolecular dehydration reaction converts the... 

This reaction may account in part for the oligomers obtained in the polymerization of pro-pene, 1-hutene, and other 1-alkenes where the propagation reaction is not highly favorable (due to the low stability of the propagating carhocation). Unreactive 1-alkenes and 2-alkenes have been used to control polymer molecular weight in cationic pol3fmerization of reactive monomers, presumably by hydride transfer to the unreactive monomer. The importance of hydride ion transfer from monomer is not established for the more reactive monomers. For example, hydride transfer by monomer is less likely a mode of chain termination compared to proton transfer to monomer for isobutylene polymerization since the tertiary carbo-cation formed by proton transfer is more stable than the aUyl carhocation formed by hydride transfer. Similar considerations apply to the polymerizations of other reactive monomers. Hydride transfer is not a possibility for those monomers without easily transferable hydrogens, such as A-vinylcarbazole, styrene, vinyl ethers, and coumarone. 

Scheme 3.1 (a) Specific acid-catalysed hydrolysis of j-carbo>yphenyl acetate where proton transfer occurs as a pre-equilibrium (b) General acid-catalysed hydration of styrene involving initial rate-limiting protonation... 

Radical copolymerizadon of substituted norbomenes mth sulfur dioxide produced alternating copolymers in excellent yields in a few hours. The copolymers had an OD of 0.25-0.33/pm at 193 nm. The acidic di(trifluoromethyl)carbinol structure incorporated into the poly(norbomene sulfone) provided an extremely fast dissolution rate in aqueous base. Terpolymerization with carbo-/>butoxynorbomene resulted in an exponential decay of the ssolution rate. In contrast to poly(styrene sulfones), however, poly(norbomene sulfones) exhibited unacceptably fast etching in... 

Yeung et al. introduced new Cinchona amino-thiocarbamate catalysts 6 and 7 for bromolactonisation of unsaturated carbo>ylic acids,and styrene-type carboxylic acids that were successfully converted to y- and 8-lactones (Scheme 15.40). 

Graham, T. H., Jones, C. M., Jui, N. T., MacMillan, D. W. C. (2008). Enantioselective organo-singly occupied molecular orbital catalysis the carbo-oxidation of styrenes. Journal of the American Chemical Society, 130, 16494-16495. 

An interesting reaction related to the selective dimerization of styrene may be the oxo-acid catalyzed addition of styrene to aromatic hydrocarbons to yield 1,1 -diphenyl-ethane derivatives (37) (Eq. (26)). This process differs from the cationic dimerization of styrene in that the unsaturated bond to be attacked by the styryl cation is aromatic, not vinylic as in the latter. Mechanistically, however, these reactions are quite similar, particularly in that both require rapid and efficient deprotonation of the carbo-cationic intermediate formed by the addition of the styryl cation. The high proton-... 

Scheme 39.11 Carbo-oxidation of styrene when the transient y-cation is intercepted by the nitro group of CAN.

---