Friedel-Crafts reaction olefins

Another important use of BCl is as a Ftiedel-Crafts catalyst ia various polymerisation, alkylation, and acylation reactions, and ia other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cyclophosphasenes to polymers (81,82) polymerisation of olefins such as ethylene (75,83—88) graft polymerisation of vinyl chloride and isobutylene (89) stereospecific polymerisation of propylene (90) copolymerisation of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerisation of norhornene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

The LAB production process (process 1) is mainly developed and licensed by UOP. The N-paraffins are partially converted to internal /z-olefins by a catalytic dehydrogenation. The resulting mixture of /z-paraffins and n-olefins is selectively hydrogenated to reduce diolefins and then fed into an alkylation reactor, together with an excess benzene and with concentrated hydrofluoric acid (HF) which acts as the catalyst in a Friedel-Crafts reaction. In successive sections of the plant the HF, benzene, and unconverted /z-paraffins are recovered and recycled to the previous reaction stages. In the final stage of distillation, the LAB is separated from the heavy alkylates. 

Another methodology that is widely used for C-C bond formation is the Heck coupling (Heck, 1985 T.suji, 1995). The Heck reaction involves the palladium-catalysed arylation of olefinic double bonds (Eqn. (12)) and provides an alternative to Friedel-Crafts reactions for attaching carbon fragments to aromatic rings. 

Under Lewis-acid-catalyzed conditions, electron-rich arenes can be added to alkenes to generate Friedel-Crafts reaction products. This subject will be discussed in detail in Chapter 7, on aromatic compounds. However, it is interesting to note that direct arylation of styrene with benzene in aqueous CF3CO2H containing H2PtCl6 yielded 30-5% zram-PhCH CHR via the intermediate PhPt(H20)Cl4.157 Hydropheny-lation of olefins can be catalyzed by an Ir(III) complex.158... 

Under the conditions of the Friedel-Crafts reaction, substances containing an olefinic double bond react in such a way that the acid chloride is added on at this bond and a saturated -chlorinated ketone is formed. When heated this substance loses HC1 and yields the unsaturated ketone ... 

This holds not only for aromatic and olefinic compounds but also for cycloparaffins which likewise take part in the Friedel-Crafts reaction. 

Linear alkylbenzenes are made from -paraffms (Cio-Cu) by either partial dehydrogenation to olefins and addition to benzene with HF as catalyst (60%) or chlorination of the paraffins and Friedel-Crafts reaction with benzene and an aluminum chloride catalyst (40%). See Chapter 24 for more information. 

The other 60% of the alkyl groups for LAS detergents are made through linear a-olefins. n-Alkanes can be dehydrogenated to a-olefins, which then can undergo a Friedel-Crafts reaction with benzene as described above for the nonlinear olefins. Sulfonation and basification gives the LAS detergent. 

The use of ionic liquids in most applications is stiU in development. The chemical industry in Europe is showing increasing interest in them, particularly for olefin dimerizations and Friedel-Crafts reactions. A two-phase loop reactor has been designed for large-scale preparations which allows for continuous reaction, separation of the product, and recycling of the ionic liquid (Chauvin and Helene, 1995). 

Olefins can be acylated with an acyl halide and a Lewis-acid catalyst in what is essentially a Friedel-Crafts reaction at an aliphatic carbon.197 The product can arise by two paths. The initial attack is by the acyl cation RCO+ (or by the acyl halide free or complexed see 1-14) at the double bond to give a carbocation ... 

The oldest method of alkylation with ethylene is the liquid phase reaction using anhydrous aluminum chloride as the catalyst. This reaction is a form of the classic Friedel-Crafts reaction and was discovered in 1879 by Balsohn. Most Lewis and Bronsted acids are known to be active for olefin alkylations. Alkylation by H2SO1, and H3PO1, was first shown by Ipatieff, et al, in 1936 who extended the reaction to isoparaffins. For the liquid phase alkylation of benzene with ethylene, however, aluminum chloride is preferred over the other acids, although a co-catalyst or promoter is usually needed to obtain efficient alkylation. AICI3 when dissolved in benzene containing some HCl forms a complex which can be simply described as ... 

The addition of a chloromethyl ether to olefinic linkages takes place under conditions similar to the Friedel-Crafts reaction and leads to y-chloro ethers. Substitution of zinc chloride for mercuric chloride as catalyst has improved the yields. Allyl chloride and chloromethyl ether react to give a high yield of l-methoxy-3,4-dichlorobutane (98%). ... 

Olefinic ketones have been obtained from the reaction of acyl chlorides or anhydrides with olefins using the conditions of the Friedel-Crafts reaction. The intermediate chloro ketones are oftentimes stable and must be treated with sodium bicarbonate or dimethylaniline to complete the de-hydrohalogenation. In this manner, 1-acetyl-1-cyclohexene (62%) ° and 1-butyryl-1-cyclohexene (60%) are prepared. 

Rare earth metal triflates are recognized as a very efficient Lewis acid catalysts of several reactions including the aldol reaction, the Michael reaction, allylation, the Diels-Alder reaction, the Friedel-Crafts reaction, and glycosylation [110]. A polymer-sup-ported scandium catalyst has been developed and used for quinoline library synthesis (Sch. 8) [111], because lanthanide triflates were known to be effective in the synthesis of quinolines from A-arylimines [112,113]. This catalyst (103) was readily prepared from poly(acrylonitrile) 100 by chemical modification. A variety of combinations of aldehydes, amines, and olefins are possible in this reaction. Use of the polymer-supported catalyst has several advantages in quinoline library construction. 

Si-H is believed to be equivalent to H-H and hence Si-H can add a C-C multiple bond to produce SiC-CH. The reaction is usually mediated by precious metal complexes such as chloroplatinic acid in a homogeneous liquid phase. This reaction may correspond to the alkylation of Si compounds with olefins and unsaturated compounds. A typical alkylation reaction is an acid catalyzed Friedel-Crafts reaction, e.g. an alkylation of benzene with propene to yield... 

It has long been known to students of the Friedel-Crafts reaction that olefins could be employed instead of the corresponding alkyl halides in alkylation reactions, since they were transformed into the alkyl halide by the added or liberated halogen hydride. The preparation of the alkyl halide may be presented as follows ... 

The liquid clathrate phase will dissolve substances that act as olefin hydrogenation catalysts, creating homogeneous hydrogenation catalysts.Polymerization catalysts comprised of stable liquid clathrate aluminoxane, aromatic solvents, and organic, inorganic, or organometallic compounds were described.Liquid clathrate compositions comprised of a metal halide, a quaternary ammonium salt, a quaternary phosphonium salt, or a ternary sulfonium salt an aluminum trihalide and an aromatic hydrocarbon have proven useful as reusable aluminum catalysts in Friedel-Crafts reactions. 

Kim and co-workers have reported that the Friedel-Crafts reaction of aza-MBH adducts of A-tosylimine derivatives 93 with arenes catalyzed by sufuric acid provides a stereoselective methodology for the preparation of stereo-chemically defined trisubstituted olefins (Scheme 3.31). They have also investigated the Friedel-Crafts reaction by using chlorobenzene and toluene as substrates however, mixtures of ortho and para isomers were obtained. 

Aluminum bromide has been finding increasing application as an acid catalyst in organic synthesis it has recently become of industrial importance in the alkylation of aromatic hydrocarbons with ethylene, and in the isomerization of normal hydrocarbons. It is also used in the polymerization of olefins, and to some extent in the Friedel-Crafts reaction. It has been found particularly useful in such reactions since it is not only more soluble in organic media, but also more active catalytically than aluminum chloride. Winter and Cramer have described a procedure for pre-... 

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