Reactive benzene alkylation

In media such as water and alcohols fluoride ion is strongly solvated by hydro gen bonding and is neither very basic nor very nucleophilic On the other hand the poorly solvated or naked fluoride 10ns that are present when potassium fluoride dis solves m benzene m the presence of a crown ether are better able to express their anionic reactivity Thus alkyl halides react with potassium fluoride m benzene containing 18 crown 6 thereby providing a method for the preparation of otherwise difficultly acces sible alkyl fluorides... 

Reactions other than those of the nucleophilic reactivity of alkyl sulfates iavolve reactions with hydrocarbons, thermal degradation, sulfonation, halogenation of the alkyl groups, and reduction of the sulfate groups. Aromatic hydrocarbons, eg, benzene and naphthalene, react with alkyl sulfates when cataly2ed by aluminum chloride to give Fhedel-Crafts-type alkylation product mixtures (59). Isobutane is readily alkylated by a dipropyl sulfate mixture from the reaction of propylene ia propane with sulfuric acid (60). 

Continuous benzene alkylation was conducted in a reactive distillation column of the type illustrated in Figure 1. The process unit comprises the following principal elements a double column of solid catalyst 32, packing columns above and below the catalyst bed, a liquid reboiler 42 fitted with a liquid bottoms product takeoff 44, a condenser 21 fitted with a water collection and takeoff, and a feed inlet... 

Dimethyl-chloronium and -bromonium ions give similar methylation results and are quite reactive even at temperatures as low as —50°C. The dimethyliodonium ion is less reactive and alkylates benzene and toluene in SO2CIF solution only when allowed to react (if necessary under pressure) at or above 0°C. 

The reactivities of alkyl halides are in the sequence RI > RBr > RCl and MeX > EtX > PrX. Benzyl hahde reactions with tin do not require catalysts (equation 2). For less reactive halides, the catalysts and promoters employed include metals (sodium, magnesium, zinc, or copper), Lewis bases (amines, triorganophosphines and -stibines, alcohols, or ethers), iodides, and onium salts (R4MX). The use of tin-sodimn alloys can result in tri- or tetraorganotin products. Electrochemical synthesis has also been reported, e.g. the formation of R2SnX2 from the oxidation of anodic tin by RX in benzene solution and the formation of ILtSn from RI (R = Me or NCCH2CH2) and cathodic tin. 

Chloromethyl)benzene behaves like an alkyl halide towards nucleophiles, although it is more reactive than alkyl halides in both Sj l and S 2 reactions. In the former case, the intermediate carbocation is... 

There are many possible approaches all involving O-aUcylation at one end, C-alkylation at the other, and cyclization. Here is one scheme you may have thought of others as good. The first step is electrophilic aromatic substitution (Chapter 22) on a reactive benzene ring (two OH groups) with a reactive allylic pyrophosphate. 

Friedel-Cn fts reaction. The reagent is not so active as aluminum chloride, for example alkylation of benzene with primary alkyl halides proceeds poorly. However, titanium tetrachloride effectively catalyzes alkylation with the more reactive r-alkyl halides and has the advantage of being soluble in organic solvents. Benzene... 

Benzene alkylation to Ethylbenzene and Iso-propylbenzene Several processes Vapour-phase, Liquid-phase or Reactive Distillation... 

Alkyl fluorides are the most reactive of the alkyl halides. Boron trichloride (BCI3), boron trifluoride (BF3), boron triiodide (BI3), and boron tribfomide (BBr3) all catalyze the reaction of alkyl fluorides and benzene, although they are ineffective catalysts for the analogous reaction of alkyl chlorides and alkyl bromides. reaction with mixed halides, the C—F bond reacts faster than the C—Cl, C—Br or C—I bond. This is consistent with the observed order of reactivity for alkyl halides with aluminum chloride (AICI3) ... 

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