1,4 Naphthoquinones

Place 20 g. of Orange II (Section IV,79) in a 600 ml. beaker and dissolve it in 250 ml. of water at 40-50°. Add, with stirring, 24-25 g. of sodium hyposulphite (Na SjO ) this discharges the colour and yields a pink or cream-coloured, finely-divided precipitate of a-amino-p-naphthol (compare Section IV,76). Heat the mixture nearly to boiling until it commences to froth considerably, then cool to 25° in ice, filter on a 

Submitted by E. A. Braude and J. S. Fawcett.1 Checked by Charles C. Price, R. S. Schreiber, R. D. Birkenmeyer, Paul F. Kirk, and William Bradley Reid, Jr. 

The crude naphthoquinone is precipitated by pouring the reaction mixture into 6 1. of water. The yellow precipitate is filtered, washed with 200 ml. of water, and dried in a desiccator. The product can be crystallized from 500 ml. of petroleum ether (b.p. 80-100°) (Note 3) and separates in the form of long yellow needles, m.p. 124-125°. The yield is 14-17 g. (18-22%) (Note 4). 

An equivalent quantity of technical chromium trioxide, ground to a fine powder, may be employed. 

It is necessary to continue vigorous stirring at this stage in order to prevent local overheating and to keep the mixture from setting to a solid mass. 

Crystallization from petroleum ether (b.p. 80-100°) is far more convenient than steam distillation as a method of purification, and a product of high purity is obtained after a single crystallization. The checkers used Skellysolve C (b.p. 88-115°) with consistent results. Crystallization from ether has also been employed.2 

---

Several substances having vitamin K. activity have been isolated from natural sources. Vitamin Ki from alfalfa oil, is 2-methyl-3-phytyl-1,4-naphthoquinone. 

Volatility in steam. Add about 0 1 g. of benzoquinone to 3 ml. of water in a test tube and boil gently. The benzoquinone dissolves to give a yellow solution, which rapidly darkens in colour. Note the irritating and characteristic odour of benzoquinone which has volatilised in the steam. Also given by />-toluquinone and 1,4 naphthoquinone but not by the other quinones mentioned above. 

Benzoquinone ( quinone ) is obtained as the end product of the oxidation of aniline by acid dichromate solution. Industrially, the crude product is reduced with sulphur dioxide to hydroquinone, and the latter is oxidised either with dichromate mixture or in very dilute sulphuric acid solution with sodium chlorate in the presence of a little vanadium pentoxide as catalyst. For the preparation in the laboratory, it is best to oxidise the inexpensive hydroquinone with chromic acid or with sodium chlorate in the presence of vanadium pent-oxide. Naphthalene may be converted into 1 4-naphthoquinone by oxidation with chromic acid. 

Dimethylbutadiene and 1 4-naphthoquinone. 2 3-Di-methylanthraquinone. In a small round-bottomed flask, fitted with a reflux condenser, place a solution of 8 g. of freshly-distUled 2 3-dimethyl-butadiene (Section 111,147) and 8 g. of 1 4-naphthoquinone (Section IV,149) in 30 ml. of ethanol, and reflux for 5 hours. Keep the resulting solution in a refrigerator for 12 hours break up the crystaUine mass, filter, and wash with 5 ml. of alcohol. The yield of crude adduct, m.p. 147-149°, is 11-5 g. recrystaUisation from methanol raises the m.p. to 150°. 

Oxidation. Naphthalene may be oxidized direcdy to 1-naphthalenol (1-naphthol [90-15-3]) and 1,4-naphthoquinone, but yields are not good. Further oxidation beyond 1,4-naphthoquinone [130-15-4] results in the formation of ortho- h. h5 ic acid [88-99-3], which can be dehydrated to form phthaUc anhydride [85-44-9]. The vapor-phase reaction of naphthalene over a catalyst based on vanadium pentoxide is the commercial route used throughout the world. In the United States, the one phthaUc anhydride plant currently operating on naphthalene feedstock utilizes a fixed catalyst bed. The fiuid-bed process plants have all been shut down, and the preferred route used in the world is the fixed-bed process. 

Naphthalenediol. This diol can be prepared by the chemical or catalytic reduction of 1,4-naphthoquinone. Both the diol and quinone are of interest because of their relation to the vitamin K family. Carboxylation of 1,4-naphthalenediol with CO2—K2CO2 followed by neutralization gives... 

Diels-Alder Reaction. In 1928, Diels and Alder discovered that 1,3-unsaturated organic compounds reacted with quinoid systems to give partially hydrogenated, cycHc compounds. In the course of their work, they found that 1 mol of 1,4-naphthoquinone [130-15-4] reacted readily with 1 mol of 1,3-butadiene [106-99-0] to give a partially hydrogenated anthraquinone (11) l,4,4a,9a-tetrahydro-9,10-anthracenedione [56136-14-2] which, on oxidation with chromic oxide, produced anthraquinone (43) ... 

The cross-conjugated system of two a,P-unsaturated carbonyl groups of both 1,2- and 1,4-quinones occurs in many polynuclear hydrocarbons, eg, 1,2-naphthoquinone [524-42-5] (8) and 1,4-naphthalenedione [130-15-4] (1,4-naphthoquinone) (9) (see Fig. 1). The carbonyl groups may be located in different rings, but occupy positions corresponding to the 1,2- or 1,4-orientation of monocyclic quinones, eg, in naphthalenes such as 2,6-naphthoquinone... 

The synthesis of optically active epoxy-1,4-naphthoquinones (69) using ben2ylquininium chloride as the chiral catalyst under phase-transfer conditions has been reported (67). 2-Meth5l-l,4-naphthoquinone (R = CH ) (31) yields 70% of levorotatory (37). 2-Cyclohexyl-l,4-naphthoquinone... 

Nucleophilic Substitution Reactions. Many of the transformations reali2ed through Michael additions to quiaones can also be achieved usiag nucleophilic substitution chemistry. In some iastances the stereoselectivity can be markedly improved ia this fashion (100), eg, ia the reaction of ben2enethiol with esters (R = CH C O) and ethers (R = 3) 1,4-naphthoquiaones. 2-Bromo-5-acetyloxy-l,4-naphthoquiQone [77189-69-6J, R = Br, yields 75% of 2-thiophenyl-5-acetyloxy-l,4-naphthoquinone [71700-93-1], R = SC H. 3-Bromo-5-methoxy-1,4-naphthoquinone [69833-10-9], R = Br, yields 82% of 3-thiophenyl-5-methoxy-l,4-naphthoquinone [112740-62-2] R = SC H. ... 

Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) [475-38-7] M 190.2, m 220-230°(dec), m 225-230°, pKEst(i) 9.5, pKEst(2) ll-l Red-brown needles with a green shine from EtOH. Also recrystd from hexane and purified by vacuum sublimation. [Huppert et al. J Phys Chem 89 5811 1985.] It is sparingly soluble in H2O but soluble in alkalis. It sublimes at 2-10mm. The diacetate forms golden yellow prisms from CHCI3, m 192-193° and the 5,8-dimethoxy derivative has m 157° (155°) (from pet ether) [Bruce and Thompson J Chem Soc 1089 7955 IR Schmand and Boldt J Am Chem Soc 97 447 1975 NMR Brockmann and Zeeck Chem Ber 101 4221 1968]. The monothiosemicarbazone has m 168°(dec) from EtOH [Gardner et al. J Am Chem Soc 74 2106 7952]. 

Naphthoquinone [130-15-4] M 158.2, m 125-125.5 . Crystd from diethyl ether (charcoal). Steam distd. Crystd from benzene or aqueous EtOH. Sublimed in a vacuum. 

Naphthoquinone reacts in 30 minutes to give l,2,3,4-tetrahydro-l,4-dioxo-naphthalene in 70% yield. After recrystallization from hexane, the product has mp 95-97° 10). 

The toxic influence exerted by Juglans nigra (black walnut) on other plants has been attributed to 5-hydroxy-1,4-naphthoquinone (juglone) (11,31). Hydrojuglone is present in the root bark, leaves, and fruit husks. This compound is not considered toxic, but it is oxidized to the toxic juglone upon exposure to air (51). Rainfall... 

Naphthoquinone [ 1,4-Naphthalenedione] Metlioxyacetic [Acetic acid, mcthoxy-] 2-Methoxvmethyl [ 1,4-Naphthalenedione, 2-(methoxymethyl)-] 50 2... 

Naphthoquinone Adipic [Hexanedioic acid] 2-(tj-Carboxy butyl) [2-Naphthalenepentanoic acid, 1,4-diliydro-1,4-dioxo-] 51 2... 

Acetoxy-1,4- naphthoquinone [ 1,4-Naphthalenedione, 2-(aoetyloxy)-] 4-Methyl-3-pentenoic [3-Pentenoic acid, 4-methyl-] 2-Acetoxy-3-(y,y-dimethylallyl) [1,4 -Naphthalen ed i one, 2-(acetyloxy)-3-(3-methyl-2-butenyl)-] 73 4... 

---