Friedel-Crafts reactions of benzene

Propiophenone. Propiophenone [93-55-0] (ethyl phenyl ketone) is a colorless Hquid with a flowery odor. It can be prepared by the Friedel-Crafts reaction of benzene and propionyl chloride in the presence of aluminum chloride (346), or by the catalytic reaction of benzoic acid and propionic acid in the presence of water (347). Propiophenone is commercially available (348), and is sold in Japan at 2700 Y/kg (349). It is used in the production of ephedrine, as a fragrance enhancer, and as a polymerization sensitizer. 

Benzophenone is produced by the oxidation of diphenylmethane (350). This free from chlorine (FCC) route is favored for perfume uses. The Friedel-Crafts reaction of benzene and benzoyl chloride in the presence of aluminum chloride is also possible this reaction may proceed in the absence of catalyst at a temperature of 370°C and pressure of 1.4 MPa (351). 

Problem 16.5 What is the major monosubstitution product from the Friedel-Crafts reaction of benzene with l-chloro-2-methylpropane in the presence of AlCl3 ... 

Would you expect the Friedel-Crafts reaction of benzene with (P)-2-chloro-butane to yield optically active or racemic product Explain. 

After succeeding in the direct synthesis of allyidichlorosilane hy reacting elemental silicon with a mixture of allyl chloride and hydrogen chloride in 1993," Jung el cil. reinvestigated the Friedel-Crafts reactions of benzene derivatives with allyidichlorosilanes in detail (Eq. (2)). 

Friedel—Crafts Reaction of Benzene and Ethylene Oxide. In the presence of molar quantities of aluminum chloride, ethylene oxide reacts with benzene to give an addition product, which is hydrolyzed to phenethyl alcohol ... 

Problem 11.42 Explain the following observations, (a) A yellow color is obtained when Ph,COH (trityl alcohol) is reacted with concentrated H2SO4, or when PhjCCI is treated with AICI,. On adding HjO, the color disappears and a white solid is formed, (b) Ph,CCl is prepared by the Friedel-Crafts reaction of benzene and CCI4. It does not react with more benzene to form PhjC. (c) A deep-red solution appears when Ph,CH is added to a solution of NaNH in liquid NH3. The color disappears on adding water, (d) A red color appears when PhjCCl reacts with Zn in C H. Oj decolorizes the solution. ... 

This process was superceded by the Friedel-Crafts reaction of benzene and ethylene oxide which is now the most important commercial process (11). Cheap ethylene oxide brought about this shift. For a short time, commercial quantities of phenylethyl alcohol were made by the Grignard reaction of phenyl magnesium chloride on ethylene oxide but this process could not compete with the Friedel-Crafts process. 

Fig. C. Friedel-Crafts reaction of benzene with 2-chloropropane.

The aluminum chloride-catalyzed Friedel-Crafbs reaction of 81 and benzene produced benzoylthiadiazole (84) in almost quantitative yield. The product of the Friedel-Crafts reaction of benzene and 3,4-bis(chlorocarbonyl)-l,2,5-thiadiazole (85) is the nonrearranged dibenzoylthiadiazole (86). The material, therefore, does not behave... 

The Friedel-Crafts reaction of benzene with 2-chloro-3-methylbutane in the presence of AlCl occurs with a carbocation rearrangement. What is the structure of the product ... 

Tne rearrangement of a primary to a tertiary urb a )on during Friedel-Crafts reaction of benzene with 1-chloro-2.2-dlmethylpropane occurs by shift of an alkyl nup with its electron... 

Haloalkylations have also been carried out with branched, unsymmetrical simple di- and poly-halides, straight-chain, unsymmetrical simple di- and poly-halides, and mixed di- and poly-halides. Schmerling et a/.have studied the Friedel-Crafts reactions of benzene with l,3-dichloro-3-methylbutane in the presence of AlCb and obtained a 28-29% yield of l-chloro-3-methyl-3-phenylbutane (equation 81). 

C13H10O, Mt 182.22, bp(,3 kPa 200.5 °C, d50 1.976, has been identified as a flavor component of grapes. It is a colorless, crystalline solid (mp 48.1 °C) with a rosy, slightly geranium-like odor. It can be prepared in several ways, for example, by Friedel-Crafts reaction of benzene and benzoyl chloride with aluminum chloride, or of benzene and carbon tetrachloride, and subsequent hydrolysis of the resulting a,a-dichlorodiphenylmethane. Benzophenone can also be prepared by oxidation of diphenylmethane. It is used in flower compositions and as a fixative. 

Amino-Y-ketobutyric acid derivatives can be prepared by Friedel-Crafts reaction of benzene, toluene, or furan with the... 

Acylation. It is not necessary to employ AICI3 as a catalyst, as in the Friedel-Crafts reaction of benzene chemistry, for acid chlorides to effect acylation of the pyrrole ring. The reaction (Scheme 7.4) occurs at mild temperatures, and it makes ketones readily available. Although pyrrole is formally a secondary amine, the reduced nucleophilicity of nitrogen does not allow acylation to take place at this site. 

Styrene is obtained almost exclusively from the catalytic dehydrogenation of ethyl benzene (600°C, metal oxide). Ethyl benzene is obtained by a Friedel-Crafts reaction of benzene with ethylene. The separation of the styrene from the tetrafunctional, and therefore cross-linkable, divinyl benzene is important. In order to prevent premature polymerization, sulfur or dinitrophenols are added before distillation and t-butyl catechol is added before storing. 

Similarly, synthetic rubber was vital to the ground-war effort in World War II, after the Japanese cut off the Allies from sources of natural rubber in Southeast Asia (see Historical Highlight in Chapter 11). A synthetic rubber was developed in an amazingly short time in a remarkable display of cooperation between government officials and industrial and academic scientists. This rubber was a copolymer (Sec. 22.1) that contained styrene as a key component. Styrene is made from ethylbenzene, which is prepared industrially by the Friedel-Crafts reaction of benzene and ethylene, as shown below. 

Benzyloxysilanes and allyloxysilanes were also utilized for Hf-catalyzed Friedel-Crafts reaction of benzene rings (Equations 24 and 25) [30]. The similar reaction system can be applied for a three-component coupling of benzaldehyde, allylsi-lane, and substituted benzenes to afford diarylpropene (65) in excellent yields (Equation 26) [31]. This method provides a short synthetic route for tamoxifen (68) (Equation 27) [32]. 

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