Biphenyl Friedel-Crafts reaction

Disulfides were shown to be intermediates in the iodine oxidation of 1,3-butadiene-l-thiols and related compounds to form thiophenes (56JOC39). Several simple disulfides were converted to thiophene derivatives under these same conditions (64JOC2372). For example, bis(2-biphenyl) disulfide (13) produced dibenzothiophene (14) in 64% yield when heated with iodine in ethylene glycol for one hour. Treatment of (13) in benzene with aluminum bromide gave (14) in 76% theoretical yield, with an equivalent amount of the thiol, 2-biphenylthiol (62JOC4111). Thus the iodine reagent is more efficient, since it oxidizes the mercaptan, formed by the Friedel-Crafts reaction of disulfide on the adjacent aromatic ring, to disulfide for further reaction, and also serves as a catalyst for the initial reaction. 

The compound 1,1-NsPsF4(CsHc)i can be prepared by the reaction between (monophenyl)phosphonitrile fluoride trimer and benzene in the presence of anhydrous aluminum chloride and triethylamine.2 In the absence of triethylamine, the product is contaminated with difficultly separable biphenyl. Triethylamine also improves the conversion of phosphonitrile chloride trimer to the geminally substituted diphenyl derivative6 by the Friedel-Crafts procedure.7 The Friedel-Crafts reaction can be used also for the preparation of the geminally substituted... 

Alkylation of biphenyl with cyclohexene gives dicyclohexylbiphenyl, which can be used as a secondary plasticizer for PVC. " " Synthesis of this plasticizer uses Friedel-Crafts reaction with aluminum chloride employed as a catalyst. The application data shows that weight loss and the retention of mechanical properties (tensile strength, elongation, and modulus) are greatly improved with this plasticizer. " A mixture of di- and tri-alkyl (usually propyl) biphenyls is used as a plastieizer for polystyrene, butadiene rubber, epoxy resin, and polyurethane. " ... 

As monomer, bis[4-fluoro-3-(p-methoxylbenzo-yl)]biphenyl that contains two pendant methox-yphenyl groups is used. It is synthesized by a Friedel-Crafts reaction of 5-chloro-2-fluorobenzoyl chloride with anisole, followed by a nickel-mediated homo-coupling reaction. 

Reagents and standards. All the chemicals used were of analytical reagent grade and were tested for purity in blank runs. Ketodase was obtained from Warner-Chilcott, Morris Plains, N.J., U.S.A. Biphenylylacetic acid was synthesized from biphenyl and acetic chloride by a Friedel-Crafts reaction followed by a Willgerodt-Kindler reaction. -Hydroxybiphenylylacetic acid was prepared in a similar way from p-methoxybiphenyl. The amino acid conjugates were obtained by reaction of biphenylylacetyl chloride and -acetoxybiphenylylacetyl chloride with the appropriate amino acid. 

In 1967 3M introduced polybiphenyldisulfones under the Astrel 360 trade name. This polymer was made by the Friedel-Crafts reaction of biphenyl-4,4 -disulfonyl chloride with diphenyl ether and exhibited a very high Eg of 277°C [26]. The structure is shown in Fig. 1.12. The price was very high, it was difficult to melt process, and had limited availability. This resin is no longer commercially available. 

Generally, higher catalyst concentration leads to side reactions. An efficient approach to minimize the side reactions is to use the minimum amounts of Friedel-Crafts catalyst (e.g., FeCl3, 0.1-4 wt%). The reaction can be performed either in bulk or in solution using, for example, nitrobenzene, dimethyl sulfone, or chlorinated biphenyls as the reaction media. 

Dichloroalkyl)chlorosilanes undergo the Friedel-Crafts alkylation type reaction with biphenyl in the presence of aluniinurn chloride catalyst to afford 9-((chlorosilyl)alkyl)fluorenes through two step reactions (Eq. (16)). The results obtained from the alkylation of biphenyl and the cyclization reaction to 5-membered-ring product are summarized in Table XIIE... 

The mechanism for the production of 9-((chlorosilyl)alkyl)(luorenes from the Friedel-Crafts alkylation reaction of biphenyl with (l,2-dichloroethyl)silane in the presence of aluminum chloride as catalyst is outlined in Scheme 4. At the beginning stage of the reaction, one of two C—Cl bondsof (1,2-dichloroethyl)silane (CICH2—CICH—SiXi) interacts with aluminum chloride catalyst to give intermediate 1 (a polar +C-CI - ( +C-C1—Al CI3) or a carbocation C AICU ... 

A second example from the same group is the synthesis of an elaborate diethynyltriphenylene derivative (Scheme 7 Table 8,entries 12,13) [58].Zn/Pd-promoted homocoupling of a 4-iodo-l,2-dialkoxybenzene furnishes the desired tetraalkoxybiphenyl, an electron-rich aromatic system. Iron trichloride-catalyzed Friedel-Crafts arylation of the biphenyl derivative with dimethoxy-benzene furnishes an unsymmetrical triphenylene derivative. Deprotection, oxidation, and subsequent Diels-Alder reaction with cyclohexadiene is followed by catalytic hydrogenation and reoxidation. TMS-CC-Li attack on the quinone delivers the alkyne modules, treatment with SnCl2 aromatizes the six-mem-bered ring, while KOH in MeOH removes the TMS groups cleanly to give the elaborate monomer. 

The Friedel-Crafts cyclization of biphenyl-2-sulfonyl chloride to give dibenzothiophene sulfone has been described (55%) ° however, thermal cyclization in octachloronaphthalene at 250°, under nitrogen, is reported to yield dibenzothiophene itself rather than the sulfone (47%). Reaction of biphenyl compounds with oleum (H2SO4 + SO3) to yield derivatives of dibenzothiophene 5,5-dioxide is widely used for the preparation of dyestuff intermediates (Section VI, E, 2). A typical example is shown in Eq. (3), starting from o-tolidine. ... 

Physical constants of several partially fluorinated biphenyls (up to the 2,2, 3,4, -5,5, 6-heptafluoro-compound), obtained by a range of classical methods including the Friedel-Crafts, Ullmann, and Balz-Schiemann reactions, have been reported, and 1,8-difluoro- or 1,4,5-trifluoronaphthalene may be obtained by conventional routes (nitration, reduction, diazotization) from 1,8-diamino- or 1,5-difluoro-naphthalene, respectively. ... 

Also obtained by reaction of EKONOU ), an aromatic polyester as Friedel-Crafts reagent, with biphenyl in triflic acid at 25° for 18 h (95%) [922]. Similar results can be obtained using hydrofluoric acid/boron trifluoride or aluminium chloride in place of triflic acid [922]. 

Ravon et al. [93] found that zinc carboxylates exhibit an exceptionally high shape selectivity in a number of alkylation reactions. They studied catalysis on MOF-5, which is the archetype of a variety of MOFs with phenylenedicarboxylate-type ligands. This MOF structure consists of coordinatively saturated Zn O cluster units and completely complexed bdc ligands. However, MOF-5 exhibits catalytic activity in the Friedel-Crafts tert-butylation of toluene and biphenyl (tert-butyl chloride as a tert-butylating agent). Unlike the case of AICI3, mainly para-alkylation occurs on this catalyst, whereas ort/io-alkylation proceeds at a low rate. This indicates the occurrence of the process within the porous structure. 

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