2,6 Dihydroxynaphthalene

Tartaric acid (200 g., 1.33 moles) is dissolved in 140 ml. of warm water, and to the cooled solution is added a solution of 5 g. of sodium potassium tartrate in 40 ml. of water. The mixture is cooled to —10°, and a solution of 4 g. of ferrous sulfate in 40 ml. of water is added in one portion. The mixture is stirred vigorously and the temperature is held at —5° while 145 ml. of 30% hydrogen peroxide is added slowly (addition requires 5-6 hours). The reaction mixture is stirred for ah additional 2.5 hours at —5° after completion of the addition. The mixture is allowed to stand for a week in an ice chest, and then the precipitated dihydroxymaleic acid is collected by filtration and dried over phosphorus pentoxide. The product contains some iron salt of dihydroxymaleic acid which gives it a pale yellow color. The yield is 42 g. or 24%. 

A mixture of 80 g. (0.24 mole) of the sodium salt of 2,7-naphthalene-disulfonic acid and 240 g. (4.2 moles) of potassium hydroxide is placed 

A solution of freshly distilled anisaldehyde (150 g., 1.10 moles) (p. 129) in 200 ml. of ethanol is mixed with a solution of 30 g. of potassium cyanide (free from cyanate) in 120 ml. of water, and the resulting mixture is heated under vigorous reflux for 2 hours. An additional 30 g. of potassium cyanide is added, and reflux is continued for another 2-hour period. After cooling, the upper layer solidifies upon seeding with a crystal of the product, and the solid is removed by filtration. The filtrate is heated under reflux for another 2-hour period with a third portion of 30 g. of potassium cyanide, and this yields an additional quantity of 4,4 -dimethoxybenzoin. The combined crude product is recrystallized from ethanol to give 110 g. (73%) of product melting at 113°. 

Kgff = 10 ) which is the reverse order of their iron(III) stability constants. These irregularities must be attributed to the importance of factors already referred to, such as bioavailability, biostability, and the kinetics of iron chelation. The increase in the oral efficacy of EHPG on conversion to the dimethyl ester (63) has already been noted. The loss of activity on sulfonatlon of 8-hydroxyqulnoline and 1,8-dlhydroxynaphthalene is another illustration of the importance of the ionic form of the chelator. 

Hydroxamlc acids representative of all of the major structural families of microbial iron chelates (65) have been evaluated. 

With the possible exception of rhodotorullc acid (vide supra) and triacetylfusarlnine C, none show activity approaching that of DFB. Several bldentate hydroxamlc acids increase iron levels in the 

ACS Symposium Series American Chemical Society Washington, DC, 1980. 

Changes in Hepatic, Splenic and Urinary Iron in Transfused Mice Treated i.p. with Potential Iron Chelators 

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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). 

In 1885, from a detailed study of juglone (52) it was proposed that its stmcture was 5-hydroxy-l,4-naphthoquinone (9). This stmcture was confirmed by oxidizing 1,5-dihydroxynaphthalene with potassium dichromate in sulfuric acid (53). Juglone occurs in walnuts as a glycoside of its reduced form, 1,4,5-trihydroxynaphthalene (54). Later it was deterrnined that the sugar is in the 4-position (10) (55). 

Juglone is most readily synthesized by Bemthsen s method. However, this method is too drastic and results in low yields (56). Somewhat better yields are obtained by using Fremy s salt (potassium nitroso disulfonate) as the oxidant (57). By using thallium trinitrate to oxidize 1,5-dihydroxynaphthalene, yields as high as 70% of juglone have been reported (58). 

Dihydroxynaphthalene [575-44-0] M 160.2, m 138-139 (with previous softening), pK st 9.4. Crystd from benzene or benzene/EtOH after treatment with charcoal. 

The Bucherer carbazole synthesis was pivotal in the preparation of the first hexahelicene 37a. Reaction of 2,7-dihydroxynaphthalene 35 with phenylhydrazine and sodium bisulfite afforded helicene 37a although in low yield. More recently, the synthesis was extended to the preparation of 37b using 2,5-dimethylphenylhydrazine 36b. ... 

Examples of palladium-catalyzed reduction are 4-chloro-2,6-di-r-butyl-phenol to 2,6-di-t-butylcyclohexanone (750 psig, 25 C) with loss of halogen 24), 1,8-dihydroxynaphthalene to 8-hydroxy-1-tetralone 30), and 2,4-dimethylphenol to 2,4-dimethylcyclohexanone (27). 

Calcium in the 10-500ng range can be determined by using the selective spectrofluorimetric reagent l,5-bis(dicarboxymethyl-aminoethyl)2,6-dihydroxynaphthalene at pH 11.7 (Ref. 32). 

Unique methods based on new principles have been developed within the past 10 years. Threonine (27,28,249) is oxidized by lead tetraacetate or periodic acid to acetaldehyde, which is determined by photometric analysis of its p-hydroxydiphenyl complex or iodometric titration of its combined bisulfite. Serine is oxidized similarly to formaldehyde, which is determined gravimetrically (207) as its dimedon (5,5-dimethyldihydro-resorcinol) derivative or photometric analysis (31) of the complex formed with Eegriwe s reagent (l,8-dihydroxynaphthalene-3,5-disulfonic acid). It appears that the data obtained for threonine and serine in various proteins by these oxidation procedures are reasonably accurate. [Block and Bolling (26) have given data on the threonine and serine content of various proteins. ]... 

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. 

Allomelanins — These are structurally different compounds containing little or no nitrogen. They are considered polymers of phenolic compounds like catechol. Fnngi prodnce melanin pigments, predominantly dihydroxyphenylalanine (DOPA)-melanin and dihydroxynaphthalene (DHN)-melanin. ... 

Sulfite during the conversion of naphthalene-1-snlfonate into 1,2-dihydroxynaphthalene (Kuhm et al. 1991), and 4-carboxybenzenesnlfonate into 3,4-dihydroxybenzoate (4-carboxycatechol) (Locher et al. 1991). 

Kuhm AE, A Stolz, K-L Ngai, H-J Knackmuss (1991) Purification and characterization of a 1,2-dihydroxynaphthalene dioxygenase from a bacterium that degrades naphthalenesulfonic acids. J Bacterial 173 3795-3802. 

An alternative to monooxygenation is realized in the hydration of the substituted cyclohexanone derived from the fission product of 1,2-dihydroxynaphthalene during the degradation of 1,2,3,4-tetrahydronaphthalene (tetralin) (Hernaez et al. 2002) (Figure 7.35). 

Eaton RW, PJ Chapman (1992) Bacterial metabolism of naphthalene construction and use of recombinant bacteria to study ring cleavage of 1,2-dihydroxynaphthalene and subsequent reactions. J Bacteriol 174 7542-7554. 

With a 5.6% concentration of poly (vinyl alcohol), the proportion of gelling agents should be approximately as given below, on the basis of the weight of the poly(vinyl alcohol) dihydric phenols 40%, trihydric phenols 30%, 1-naphthols 8%, and dihydroxynaphthalenes 3.5%. 

Naphthoquinone was completely eliminated and hydrogenated to naphthol and dihydroxynaphthalene as reported by Brower (15). 

Al-Ghannam et al. [25] described a simple fluorimetric procedure for determination of three pharmaceutical compounds containing thiol groups, including penicillamine. In this method, the drugs are treated with 1,2-naphthoquinone-4-sulfonic acid. The later compound is reduced to l,2-dihydroxynaphthalene-4-sulfonic acid, which is measured fluorimetrically (excitation = 318 nm, emission = 480 nm). The method is sensitive to 0.5 1.5 pg/mL, with a detection limit of 0.05 pg/mL (S/N = 2). 

With catechol or with 2,3-dihydroxynaphthalene, dispirans of the [6.0.6.l]type are formed 18) ... 

The author17 explains the difference by involvong the peri-effect in 1,8-dihydroxynaphthalene. 

Antia et al. [96] proposed a colorimetric method comprising a concentration step and a reaction with 2,7-dihydroxynaphthalene. This method has a detection limit of 0.1 mg/1. Methods comprising concentration by adsorption on alumina, followed by elution and colour development, yielded a detection limit of 5 ng/1 [97,98]. These methods have not been too successful in hands other than those of the original authors, possibly because of the amount of manipulation necessary in the analysis. 

Tin adducts of the type Sn(C>2R) were obtained in the electrolysis of aromatic diols with tin as the sacrificial anode R(OH)2 = 1, 2-dihydroxybenzene (catechol), tetrabromo-cathechol, 2,3-dihydroxynaphthalene and 2,2/-dihydroxybiphenyl yields, based on mass loss of the anode, range within 75-94 %136. 

Fig. 47. Catalytic selectivity as a function of Ti content in Ti-MCM-41 for 1-naphthol hydroxylation with aqueous H202. H202 selectivity (mol%) = (number of moles of H202 utilized in product (1, 4-naphthoquinone, 1,4-dihydroxynaphthalene and 1,2-dihydroxynaphthalene) formation/-number of moles of H202 fed) X 100 [data from Chaudhari et al. (277)].

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