Benzene advantages/disadvantages

There are advantages and disadvantages in both processes the solvent process requires no special equipment but uses an excess of benzene whose recovery adds to the cost of the product. The bad mill method uses no excess benzene but requires special equipment which has frequent mechanical problems. 

Butadiene has the advantage of a relatively low heat of reaction (995 kJ/ mol compared with 1875 kJ/mol in the oxidation of benzene), but the disadvantage of a relatively high price compared with the other -C4 hydrocarbons. Good prospects has the n-butane route. Keeping the n-butane conversion at about 15%, the yield of maleic acid anhydride amounts to 50-60 mol %. 

As a result, inert and aprotic solvent toluene is suitable for the titration of weak bases in non-aqueous media as solvent, although benzene which is more carcino-genic aromatic hydrocarbon used widely in literature for non-aqueous titrations. The major advantage of toluene is tliat it does not compete for protons with the reactant in the titrations because of its autoprotolysis constant approaching zero. The major disadvantages of solubility can be removed by using small amount of amphiprotic solvents. 

In the traditional process, developed since the 1930s, alkylation is performed by reacting benzene and ethylene in the presence of a Friedel-Crafts catalyst (i.e., AICI3-HCI) under mild conditions. Table 2.8 shows the advantages and disadvantages of this process. Starting from the mid-1960s different zeolite-based... 

Table 2.8 Advantages and disadvantages of the alkylation of benzene with ethylene catalyzed by AICI3. Source adapted from Perego and Ingallina [221].

Polyalkylation, an advantage here, can be a nuisance with Friedel-Crafts alkylations as can the rearrangement of primary alkyl halides. Thus, the alkyl halide (8) gives a mixture of (9> and (10) with benzene and if we want to make compound (11) we must use the Friedel-Crafts acylation, which suffers from neither of these disadvantages, and then reduce the carbonyl group (see Chapter 24). 

Ethylbenzene (EB) is currently produced by alkylation of benzene with ethylene, primarily via two routes liquid-phase with AlCl, catalyst, or vapour-phase in catalytic fixed bed reactor (Ullmann, 2001). Examine the differences, as well as advantages and disadvantages of these routes. List pros and cons in selecting suitable reactors. 

There are two main techniques used for measurement of one-electron reduction potenticils in solution pulse radiolysis and cyclic voltammetry. They both have their advantages and disadvantages which will discussed here. The acidity of substituted benzene radical cations have been studied mainly by pulse radiolysis but a few measurements using laser flash photolysis have also been reported. 

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