Alkylation with Other Alkenes

5 Alkylation with Other Alkenes - Fellman pointed out that the composition of 2,6-diethylnaphthalene (2,6-DEN) and the 2,6-/2,7-DEN ratio is an important indicator for the selective ethylation of naphthalene.77 The selective ethylation requires the 2,6-DEN composition to exceed thermodynamic equilibrium and the 

7-DEN ratio to be higher than 1.0. Takeuchi and his co-workers confirmed experimentally over SA, HY, and HM that all of 2,6-DEN compositions were less than 27%, which was the estimated value at thermodynamic equilibrium, although the ratios were higher than l.O.78 Other DEN isomers having at least 

Moreau and his co-workers showed that the higher alkylating reagent, cyclohexene or cyclohexyl bromide, gave p, 3-dicyclohexylnaphthalenes selectively over HY.79 81 However, the 2,6-/2,7- ratio was almost unity. 

5 Alkylation with Other Alkenes - Fellman pointed out that the composition of 2,6-diethylnaphthalene (2,6-DEN) and the 2,6-/2,7-DEN ratio is an important indicator for the selective ethylation of naphthalene. The selective ethylation requires the 2,6-DEN composition to exceed thermodynamic equilibrium and the 2,6-/2,7-DEN ratio to be higher than 1.0. Takeuchi and his co-workers confirmed experimentally over SA, HY, and HM that all of 2,6-DEN compositions were less than 27%, which was the estimated value at thermodynamic equilibrium, although the ratios were higher than 1.0. Other DEN isomers having at least 

---

Alkylation with Other Alkenes over H-Mordenite - The steric restriction of the transition state is essential for high selectivity in the isopropylation of biphenyl. The selectivity should be highly dependent on the size of the alkene. 

As in the case of dimerizations, MCP derivatives are known to undergo metal-catalysed [2 + 2] codimerizations with other alkenes in a few cases [2]. The examples are limited to strained olefins, such as norbornadiene (572) (Scheme 79) [152] and cyclobutene (574) (Scheme 80) [153], and to alkyl acrylates (Table 46) [154] and always compete with the alternative [3 + 2] addition of TMM species. 

On the basis of previous results, the Rueping group started to study alkylations with activated alkenes and nucleophiles other than arenes. Recently, Lewis- and Brpnsted-acid-catalyzed hydroalkylation procedures with 1,3-dicarbonyl compounds as nucleophiles have been developed [69, 70]. These reactions primarily utilized Pd... 

In alkylation of benzene with both ethylene and propylene di- and polyalkylates are also formed. In alkylation with propylene 1,2,4,5-tetraisopropylbenzene is the most highly substituted product steric requirements prevent formation of penta-and hexaisopropylbenzene. On the other hand, alkylation of benzene with ethylene readily even yields hexaethylbenzene. Alkylation with higher alkenes occurs more readily than with ethylene or propylene, particularly when the alkenes are branched. Both promoted metal chlorides and protic acids catalyze the reactions. 

Metal-catalyzed [2+2]-eodimerizations of methylenecyclopropanes with other alkenes are limited to a few cases. Again the formation of the formal [3+2]-cyclo-adducts is competing. As cosubstrates, strained alkenes (Eqs. 71 and 72) and alkyl acrylates could be applied successfully, the latter being of more interest from a synthetic point of view. 

Linear mono C10-C13 alkylbenzenes (LAB) which are used in the production of biodegradable surfactants are produced industrially by benzene alkylation with linear alkenes, HF or AICI3 being used as catalysts (1,2). Because their degradabUityis very high, the 2-phenylalkanes are preferred to the other isomers... 

This is carried out by operating a chemiluminescent NOj analyzer (cf. NO, analysis) at a NO excess condition. As the reaction of ozone with NO is faster and gives more intense CL than that with ethene, this method is preferred for some purposes in which a fast response is required (i.e., aircraft flux measurements). However, this CL method is subject to interference from water vapor and may contaminate the environment with NO. The ozone-NO reaction is also known as a gas-phase titration reaction, in which sample gas is mixed with a low-concentration standard NO gas and the NO2 formed in quantities equivalent to ozone is determined by an appropriate method. While CL reactions of ozone with other alkenes, alkyl sulfides, phosphine, arsine, and stibine... 

Adsorption of ethylene on a hydrogen-covered Fe(lOO) surface occurs without reaction at 1 lOK, but at 160K reversible insertion occurs ro give surface Fe-Et groups. These do not react with further H2, but coadsorption of CO induces reductive elimination of ethane. Similar studies with other alkenes showed that the surface alkyls formed are predominantly teiminal. 1... 

Experimental measurements of dipole moments give size but not direction We normally deduce the overall direction by examining the directions of individual bond dipoles With alkenes the basic question concerns the alkyl groups attached to C=C Does an alkyl group donate electrons to or withdraw electrons from a double bond d This question can be approached by comparing the effect of an alkyl group methyl for exam pie with other substituents... 

Acids other than hydrogen halides also add to the carbon-carbon bond of alkenes Concen trated sutfuric acid for example reacts with certain alkenes to form alkyl hydrogen sulfates... 

We have seen this situation before m the reaction of alcohols with hydrogen halides (8ection 4 11) m the acid catalyzed dehydration of alcohols (8ection 5 12) and m the conversion of alkyl halides to alkenes by the El mechanism (8ection 5 17) As m these other reactions an electronic effect specifically the stabilization of the carbocation intermediate by alkyl substituents is the decisive factor The more stable the carbo cation the faster it is formed... 

Uses. Magnesium alkyls are used as polymerization catalysts for alpha-alkenes and dienes, such as the polymerization of ethylene (qv), and in combination with aluminum alkyls and the transition-metal haUdes (16—18). Magnesium alkyls have been used in conjunction with other compounds in the polymerization of alkene oxides, alkene sulfides, acrylonitrile (qv), and polar vinyl monomers (19—22). Magnesium alkyls can be used as a Hquid detergents (23). Also, magnesium alkyls have been used as fuel additives and for the suppression of soot in combustion of residual furnace oil (24). 

In the next step, one of the borane-hydrogens is transferred to a sp -carbon center of the alkene and a carbon-boron bond is formed, via a four-membered cyclic transition state 6. A mono-alkyIborane R-BH2 molecule thus formed can react the same way with two other alkene molecules, to yield a trialkylborane R3B. In case of tri- and tctra-substituted alkenes—e.g. 2-methylbut-2-ene 7 and 2,3-dimethylbut-2-ene 9—which lead to sterically demanding alkyl-substituents at the boron center, borane will react with only two or even only one equivalent of alkene, to yield a alkylborane or mono alky Iborane respectively ... 

Hydrozirconation of terminal alkynes R-C=CH (R= aryl, alkyl) with 1 affords terminally ( )-Zr-substituted alkenes with high efficiency and excellent stereochemical and regiochemical control (>98%). These alkenylzirconocene complexes are of particular interest for synthetic use [136, 143, 144]. Moreover, beside the electropositive halogen sources [145] and heteroatom electrophiles [3] used in the pioneering studies to directly cleave the Zr-C bond, ( )-vinyl-Zr complexes were recently transformed into a number of other trans-functionalized alkenes such as ( )-vinyl-sul-fides[146], vinylic selenol esters [147], vinyl-sulfones [148], vinyl-iodonium [149], vinyl-(R0)2P(0) [150], and vinilic tellurides [143]. 

This reaction is not usually a major factor with alkenes bearing only alkyl groups, but is important for vinyl ethers and other alkenes with donor substituents. These... 

---