Anthraquinones nucleophilic substitution

Nucleophilic substitution reactions, to which the aromatic rings are activated by the presence of the carbonyl groups, are commonly used in the elaboration of the anthraquinone nucleus, particularly for the introduction of hydroxy and amino groups. Commonly these substitution reactions are catalysed by either boric acid or by transition metal ions. As an example, amino and hydroxy groups may be introduced into the anthraquinone system by nucleophilic displacement of sulfonic acid groups. Another example of an industrially useful nucleophilic substitution is the reaction of l-amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) (76) with aromatic amines, as shown in Scheme 4.5, to give a series of useful water-soluble blue dyes. The displacement of bromine in these reactions is catalysed markedly by the presence of copper(n) ions. 

Photochemical nucleophilic substitution of some simple anthraquinone derivatives has been reported by Griffiths and Hawkins.<145) Irradiation of 1-methoxyanthraquinone (90) in ammonia solution resulted primarily in 1-aminoanthraquinone (91) ... 

Carbanions of chloromethyl aryl sulfone (Ar = Ph or p-tolyl) in DMSO-Bu OK react with 9,10-anthraquinone by vicarious nucleophilic substitution or addition to the... 

Nucleophilic substitution by a hydroxyl ion displaces a hydride ion. Alizarin plants were subsequently built in Germany and England [17-19]. The procedure developed by Koch (B.A.S.F.) is based on the sulphonation of the anthraquinone with oleum followed by alkali fusion under addition of an oxidising agent (Fig. (4)) [20]. 

A convenient alternative to protection relies on the incorporation of a labile moiety available for post-polymerization functionalization by nucleophilic substitution [84]. A more versatile approach incorporates a terminally halogenated alkyl substituent as a site for post-polymerization via nucleophilic substitution. Anthraquinone, amine, thiol and carboxylic acid derivatives have been prepared thereby. Complete conversion is possible [46, 47]. Irregular examples include conversion to iodo and thiol derivatives [85]. 

Formation of C—C links in the anthraquinone molecule, especially substitutions with aryl moieties, proceed via copper-catalyzed nucleophilic exchange of halogenated anthraquinone compounds. These methods include dimerization of 1 -aminoanthraquinone. 

The Friedel-Crafts reaction, which proceeds via electrophilic aromatic substitution, as illustrated in the following scheme, is unique to the manufacture of anthanthrone pigments. Most other polycyclic anthraquinone pigments are synthesized via nucleophilic ring closure. 

A more rigidly parallel pair of bonds for the projection of chromophores are the 1,8 positions of anthracene and anthraquinone. The respective 1,8-dichlorides undergo a limited substitution chemistry, which we extended as shown in Equation 2 to synthesize parallel-directed but weakly dipolar phthalimides. In principle, the use of donor-substituted phthalimide nucleophiles in the reaction of Equation 2 would give a fully additive pair of strong dipoles however, this has not yet been accomplished. 

The nucleophilic displacement on an anthraquinone core and also the electrophilic substitutions described above are limited to the synthesis of angucy-clines with an aromatic ring B. 

Electron transfer is the rate-determined step, and collapse of the intermediate species gives a o-complex. Radical cations of polycyclic aromatic hydrocarbons react with nucleophiles and radicals to yield substituted compounds. The oxidation of anthracene to 9,10-anthraquinone involves the reaction of radical cations with water followed by one-electron transfer and deprotonation ... 

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