2,7-Dihydroxynaphthalene, coupling

Naphthalenediol. 1,5-Dihydroxynaphthalene or Asurol is a colorless material which darkens on exposure to air. It is manufactured by the fusion of disodium 1,5-naphthalenedisulfonate with sodium hydroxide at ca 320°C in high yield. 1,5-Naphthalenediol is an important coupling component, giving ortho-a2o dyes which form complexes with chromium. The metallised dyes produce fast black shades on wool. 1,5-Naphthalenediol can be aminated with ammonia under pressure to 1,5-naphthalenediamine. 

Dihydroxynaphthalene [83-56-7] behaves similarly to 1-naphthol coupling takes place mainly in the 4-position by simple diazonium compounds, and in the 2-position with diazophenols. Diazotized 2-arninophenol-4-sulfonic acid [98-37-3] couples with 1,5-dihydroxynaphthalene to produce the important mordant dye Diamond Black PV [2052-25-7] (see stmcture 53) (Cl Mordant Black 9 Cl 16500). 

The rate constants in Figure 5-3 were measured by injecting the solution of the (E)-diazoate into a buffer solution that also contained a highly reactive coupling component (2-naphthol-3,6-disulfonic acid, except at pH values below 2.5, where l,8-dihydroxynaphthalene-3,6-disulfonic acid was used instead). The diazonium ion formed reacts rapidly with these naphthols, and the concentration of the corresponding azo compounds was determined spectrophotometrically. 

With the bisoxazoline hgand (S)-Phbox and CuCl, the asymmetric oxidative couphng of 2-naphthol and hydroxy-2-naphthoates resulted in an asymmetrically substituted 2,2 -binaphthol with ee s of up to 65% [260]. On the basis of the previous results obtained with this catalyst system, the asymmetric oxidative cross-coupling polymerization of 2,3-dihydroxynaphthalene [261] and methyl 6,6 -dihydroxy-2,2 -binaphthalene-7,7 -dicarboxylate [262] as well as the copolymerization of 6,6 -dihydroxy-2,2 -binaphthalene and dihexyl 6,6 -dihydroxy-2,2 -binaphthalene-7,7 -dicarboxylate with Cu diamine catalysts were carried out imder aerobic conditions, using O2 as the oxidant, and a cross-coupling selectivity of 99% was achieved [263]. 

They next studied the asymmetric oxidative polymerization of achiral 2,3-dihydroxynaphthalene (Scheme 42). The polymerization of this monomer with CuCl2-(-)-sparteine complex resulted in a low yield and gave a low molecular weight oligomer, whereas the polymerization with CuCl-(S)-Phbox quantitatively gave a polymer with Mn of 10 600-15 300. The enantioselectiv-ity attained in this polymerization, however, was estimated to be low, with 43% ee from the model reaction [169]. When vanadyl sulfate (VOSO -Phbox complex was used instead of the copper catalyst system, the enantioselectivity was improved up to 80% ee [170]. Asymmetric cross-coupling polymerization of two kinds of naphthol derivatives was also reported [171,172]. 

Dihydroxynaphthalenemono- and disulfonic acids couple so rapidly, even the second time, that the coupling is carried out in acetic acid solution containing sodium acetate, using diazotized p-aminoacetanilide. With many of the acids, the coupling requires several hours, as, for example, with chromotropic acid (l,8-dihydroxynaphthalene-3,6-di-sulfonic acid). In this case, also, the dye is highly soluble and separates slowly from the unreacted chromotropic acid so that considerable care must be exercised. 

Diazotised p-aminophenylarsinic acid is coupled with H acid in alkaline solution and the brownish-violet product cooled and stirred with diazotised diehlorobenzidine. The resultant dyestuff is a glistening dark brown powder, ginng a deep blue solution in water. In place of benzidine or diehlorobenzidine the following may be used tolidine, dianisi-dine, or diaminophenyl urea. Instead of H acid, S-amino-5-naphthol-7-sulphonic acid (J acid), 1 8-aminonaphthol-4-sulphonie acid (S acid or 1 8-dihydroxynaphthalene-8 6-di.sulphonie acid (chronio trope acid) may be employed. 

Lead dioxide will oxidise 4,4 -(trimethylene)bis(2,6-di-t-butylphenol) leading to formation of a dispiro-compound by intramolecular cyclisation at the 4,4 -positions, and irradiation of this compound in a methylcyclohexane matrix at — 150°C gives 4,4 -(trimethylene)bis(2,6-di-t-butylphenoxy) diradical as a stable triplet species. Rose Bengal photooxidation of 2,3-dihydroxy-naphthalene and 2,7-dihydroxynaphthalene in basic aqueous solution gives the l,r-dimeric products by coupling of the radicals formed by electron transfer either to the excited sensitizer or to 02( Ag). ° The dimer which originates from 2,7-dihydroxynaphthalene is subject to further oxidation to 6,7-dihydroxyperylene-l,12-quinone. Irradiation of the dimethoxyphenol (82) under constant current electrolysis leads via (83) to formation of the substituted tricyclo[5.4.0.0 ]undec-8-ene (84) which can be converted into ( )-isoitalicene (85 R = Me, R = H). ... 

Long-range C-N couplings have been reported by Lycka et al for the product of the coupling of benzenediazonium chloride with 1,3-dihydroxy-naphthalene and benzenediazonium chloride with 1,5-dihydroxynaphthalene. 

Starting from an optically active dimer, tetramer, or octamer of 2,3-dihy-droxynaphthalene derivatives, Tsubaki and co-workers realized the synthesis of numerous optically active oligonaphthalene products by second-order asymmetric transformation under amine-copper conditions (Scheme 3.17). On the other hand, Okamoto and co-workers achieved asymmetric oxidative coupling polymerization (AOCP) reactions to synthesize poly(2,3-dihy-droxy-l,4-naphthylene) derivatives (Scheme 3.18). The starting materials of AOCP reactions can be either partially protected tetrahydroxybinaphthale-nes or 2,3-dihydroxynaphthalene. The chiral Cu complexes ligated by (-)-sparteine or bisoxazolines were identified as suitable catalysts for these reactions. However, the enantioselectivity attained in these AOCP reactions was estimated to be low. 

Scheme 9.19). The enantioselectivity during the polymerisation was estimated to be over 80% enantiomeric excess. During the course of their study on the stereocontrolled synthesis of poly(2,3-dihydroxynaphthalene) by AOCP, Habaue found that the novel system, VO(stearate)2-D-tartaric acid lithium salt, showed a catalytic activity with much higher stereocontrol than that of the above-mentioned vanadyl sulfate-Phbox catalyst. However, Habaue s catalytic system exhibited no activity for the oxidative coupling of other 2-naphthol derivatives. 

S6ls. give dark brown col. with PeQa Boil ag. sol. —> 1 2-dihydroxynaphthalene-3 6-disulphonic acid. Reduces NH3.AgNOs. Does not couple with diazo-comps. Mono-Na salt is the developer Diogen. 

Oxidative Poiymerization of Naphthoi Derivatives. Oxidative polymerization of 2-naphtol (109) and 1,5-dihydroxynaphthalene (110) has been done using enzyme catalysts. Solid-state polycondensation of 2,6-dihydroxynaphthalene with FeCls catalyst (111) has been accomplished. Asymmetric oxidative coupling polymerization of 2,3-dihydroxynaphthalenes and their derivatives was achieved by chiral copper catalysts (112-115). 

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