A-alkene

DiisononylPhthalate andDiisodeeylPhthalate. These primary plasticizers are produced by esterification of 0x0 alcohols of carbon chain length nine and ten. The 0x0 alcohols are produced through the carbonylation of alkenes (olefins). The carbonylation process (eq. 3) adds a carbon unit to an alkene chain by reaction with carbon monoxide and hydrogen with heat, pressure, and catalyst. In this way a Cg alkene is carbonylated to yield a alcohol a alkene is carbonylated to produce a C q alcohol. Due to the distribution of the C=C double bond ia the alkene and the varyiag effectiveness of certain catalysts, the position of the added carbon atom can vary and an isomer distribution is generally created ia such a reaction the nature of this distribution depends on the reaction conditions. Consequendy these alcohols are termed iso-alcohols and the subsequent phthalates iso-phthalates, an unfortunate designation ia view of possible confusion with esters of isophthaUc acid. 

Identify which protonation reaction alkene A protonated alkene A, alkene B protonated alkene B)... 

A Alkenes can be converted into alcohols by acid-catalyzed addition of water. Assuming that Vlarkovnikov s rule is valid, predict the major alcohol product from each of the following alkenes. 

These carbene (or alkylidene) complexes are used for various transformations. Known reactions of these complexes are (a) alkene metathesis, (b) alkene cyclopropanation, (c) carbonyl alkenation, (d) insertion into C-H, N-H and O-H bonds, (e) ylide formation and (f) dimerization. The reactivity of these complexes can be tuned by varying the metal, oxidation state or ligands. Nowadays carbene complexes with cumulated double bonds have also been synthesized and investigated [45-49] as well as carbene cluster compounds, which will not be discussed here [50]. 

Reduction of acetylenes can be done with sodium in ammonia,220 lithium in low molecular weight amines,221 or sodium in HMPA containing /-butanol as a proton source,222 all of which lead to the A-alkene. The reaction is assumed to involve successive electron transfer and protonation steps. 

Fig. 8.6. Representation of it bonding in a alkene-metal cation complex.

Fig. 9 Comparison of polar and steric effects of alkyl groups on bromination rates of linear ( ), branched (O) and adamantyl (A) alkenes in acetic acid and in methanol (Ruasse and Zhang, 1984 Ruasse et al., 1990). Polar effects are identical in both solvents [full line, eq. (24)], but steric effects differ. Deviations of branched alkenes are attributed to steric inhibition of nucleophilic solvation by methanol.

In comparison with the platinum catalysts, rhodium catalysts are much more reactive to effect addition of bis(catecholato)diboron even to non-strained internal alkenes under mild reaction conditions (Equation (5)).53-55 This higher reactivity prompted trials on the asymmetric diboration of alkenes. Diastereoselective addition of optically active diboron derived from (li ,2i )-diphenylethanediol for />-methoxystyrene gives 60% de (Equation (6)).50 Furthermore, enantioselective diboration of alkenes with bis(catecolato)diboron has been achieved by using Rh(nbd)(acac)/(A)-QUINAP catalyst (Equation (7)).55,56 The reaction of internal (A)-alkenes with / //-butylethylene derivatives gives high enantioselectivities (up to 98% ee), whereas lower ee s are obtained in the reaction of internal (Z)-alkenes, styrene, and a-methylstyrene. 

SCHEME E The biradical model for the direct ,Z-photoisomerization of (a) alkenes and (b) conjugated dienes... 

On the other hand, the extent to which RDA reactions occur among various ste-reoisomeric bicyclic A -alkenes does not much depend on the stereochemistry of the ring juncture (Scheme 6.49b). These results were interpreted in terms of RDA reactions that do not follow orbital symmetry rules established for thermal reactions, and therefore rather proceed in a step-wise fashion. [112]... 

A Alkenes, Icno->no, Glasson and Tuesday ko, from Japar t al. " k(iH from Morris and Niki k from Furayama et a/. ... 

SCHEME 77. Mo-catalyzed epoxidation of cyclic and a-alkenes with H2O2 in two-phase solvents... 

The FOZ of A -alkenes singly substituted on position 3 with an alkyl group or with various open-chain and ring ketones (299) can be structurally characterized by H and NMR spectroscopy. Thus, with one exception the proton denoted as H shows a singlet at 5 = 4.98 to 5.04 ppm whereas H and H" show a singlet and a triplet, respectively. 

ZnCl2 is essential. The reaction was utilized in the synthesis of strophanthidin. Only the a, / -alkene in the a, (i- and 7, (5-unsaturated ketone 51 is reduced selectively[47]. Triethoxysilane is another reducing agent of the enone 52 and simple alkenes[48]. 

F-Teda BF4 is effective for the selective addition of fluorine to steroids in good yield, re-gioselectively and, in many cases, stereoselectively at the 6- and 16-positions, under very mild reaction conditions (Table 7).92 Further, 6 will also efficiently fluorinate silyl and alkyl enolates, enamides, carbanions, a-alkenes and actived aromatic compounds (Table 8). As an extension of this method F-Teda BF+ has been used for the electrophilic fluorination of (fluorovinyl)tin compounds affording terminal fluoroalkenes (see Table 9).88... 

Carbon-13 shifts of enamines [342] follow the behavior described for other donor substituted alkenes (Sections 4.4.3 and 4.6.2). Electron release by the dialkylamino group has two consequences The inductive electron withdrawal at the a alkene carbon is reduced (Za 10-15 ppm) compared with the a increments of aliphatic amines (Table 4.43). Further, electron density at the fi olefinic carbon increases, as indicated by considerable shieldings in pyrrolidino- and morpholinoalkenes. 

Smittenberg, J., and D. Mulder, Relation Between Refraction, Density and Structure of Series of Homologous Hydrocarbons I. Empirical Formulae for Refraction and Density at 20°C of n-Alkanes and n-a-Alkenes. Recueil, 1948 67, 813-825. 

Identify which protonation reaction (alkene A —> protonated alkene A, alkene B —>protonated alkene B) is more favorable. The energy of proton is given at right. Compare geometries of the two alkenes. Which is more strained Why How is this likely to affect the proton affinity Compare electrostatic potential maps for the two alkenes. Is the n bond in one more susceptable to protonation than that in the other Compare maps for the two protonated forms. Is the charge in one more delocalized than that in the other Suggest an explanation to account for both the reactivity difference and the structural changes. 

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