2- naphthol production

The most important process to produce 1-naphthalenol was developed by Union Carbide and subsequently sold to Rhc ne-Poulenc. It is the oxidation of tetralin, l,2,3,4-tetrahydronaphthalene/719-64-2] in the presence of a transition-metal catalyst, presumably to l-tetralol—1-tetralone by way of the 1-hydroperoxide, and dehydrogenation of the intermediate ie, l-tetralol to 1-tetralone and aromatization of 1-tetralone to 1-naphthalenol, using a noble-metal catalyst (58). 1-Naphthol production in the Western world is around 15 x 10 t/yr, with the United States as the largest producer (52). 

Substrate/product kinetic curves have been presented by the authors135 for the growth of Pseudomonans sp. strain S-313 with 5-amino-1-naphthalenesulphonate as the sulphur source in a succinate-containing medium in the presence of 1602 only. However MS-identification of the 5-amino-1-naphthol product was presented both for cultures grown in... 

Naphthol production in the Western world is around 15,000 tpa, with the USA as the largest producer. 

Naphthalenol. 2-Naphthol or p-naphthol or 2-hydroxynaphthalene/7i3 -/5 -i7 melts at 122°C and boils at 295°C, and forms colorless crystals of characteristic, phenoHc odor which darken on exposure to air or light. 2-Naphthol [135-19-3] is manufactured by fusion of sodium 2-naphthalenesulfonate with sodium hydroxide at ca 325°C, acidification of the drowned fusion mass which is quenched ia water, isolation and water-washing of the 2-naphthalenol, and vacuum distillation and flaking of the product. A continuous process of this type has been patented (69). The high sulfate content ia the primary effluent from 2-naphthol production is greatiy reduced ia modem production plants by the recovery of sodium sulfate. 

Substrate Medium Conversion (%) Naphthol Product distribution (%) C-l c-3 coupling coupling C-6 coupling... 

Stabilized ketene 6S. For l, 2 -disubstituted epoxide, species 6S undergoes 6-endo-dig electrocyclization (path b) [24] to form the six-membered ketone 66, ultimately giving naphthol products. l, 2, 2 -Trisubstituted epoxide species 6S undergoes 5-endo-dig cyclization (path a) to give the ketone species 67, finally producing l-alkylidene-2-indanones. The dialkyl substituent of the epoxide enhances the 5-endo-dig cyclization of species 65 via formation of a stable tertiary carbocation 67. We observed similar behavior for the cyclization of (o-styryl)ethynylbenzenes [15, 16]. Formation of 2,4-cyclohexadien-l-one is explicable according to 6-endo-dig cyclization of a ruthenium-stabilized ketene, vhich ultimately afforded the observed products [25]. 

Above 60°C, the naphthol products typically undergo migration of the (CO)3Cr moiety, e.g., equation (16). 

Nitrocyclohexadienones are effective nitrating agents for naphthols products are obtained from reactions in dry diethyl... 

In his initial paper in 1975, D6tz reported that the thermal cycloaddition of pentacar-bonyl(methoxyphenylcarbene)chromium with diphenylacetylene in di-n-butyl ether yielded a chromium-complexed 4-methoxy-l-naphthol [2]. Soon thereafter, he related that the same reactants in w-heptane produced not only naphthol product, but also indene, furan, and cyclobutenone products [4]. As it turned out, these results foreshadowed the extraordinary richness of organic structural types that may be derived from cycloadditions of alkynes with Fischer carbenes, as well as very recent contributions to reaction chemoselectivity through control of reaction conditions. Indeed, in the years since, the field has seen the introduction of a number of newly discovered cycloaddition types and, maybe more importantly, has... 

Cyclobutenones are fairly common side-products in the reaction of chromium arylalkoxy-carbenes with internal alkynes. As indicated in Scheme 5-1, the branch point in the formation of cyclobutenone versus naphthol products is believed to be vinylketene intermediate 4, which may undergo electrocyclic ring closure to 9, followed by reductive elimination to the product [7 a]. Cyclobutenone formation occurs only in the presence of internal or external ligands that can coordinate to unsaturated chromium species sufficiently well to prevent complexation to an internal n-system and thus divert the system toward 9. Depending on the alkyne and aryl substitution patterns and the reaction conditions, cyclobutenone formation can be made to predominate. Thus, solvents of good coordinating ability such as acetonitrile, o-OMe aryl substitution (which allows internal coordination to chromium), and bulky alkynyl substituents all favor cyclobutenone formation [Eq. (23)] [13]. In fact, the effect of solvent alone can be even more dramatic for the reaction partners in Eq. (21), a 0.5 M concentration of the carbene complex in acetonitrile gives instead a 78 % yield of cyclobutenone and only a combined 17 yield of quinone and indene products [9]. 

Purification of the crude 2-naphthol is carried out by vacuum distillation. The high sulfate content in the primary effluent from 2-naphthol production is greatly reduced in modem production plants by the recovery of sodium sulfate. 

Tao, Y. Bentley, W. E. Wood, T. K. Phenol and 2-naphthol production by toluene 4-monooxygenases using an aqueous/dioctyl phthalate system. Appl. Microbiol. Biotechnol. 2005, 68, 614-621. 

An organocatalytic method has been developed which utilizes the Lewis acidic character of the trityl cation. For example, -naphthol condenses with benzaldehyde and acetamide to give the l-amidoalkyl-2-naphthol product (215). The synthesis is done under solvent-free conditions at 70 °C. The trityl chloride ionizes in the mixture to form the carbocation and this coordinates to the benzaldehyde to initiate the conversion. 

CNTs can also lead to the ultrasensitive bioelectronic detection of DNA hybridization [51]. For example, multiwall CNT can be used as carriers for several thousands alkaline-phosphatase enzyme tracers and for accumulating the a-naphthol product of the enzymatic reaction (Figure 11.6). Such carriers relying on the alternate... 

In contrast, kinetic studies of the reaction between [Cr(CO)5 C(Ph)OMe ] and various arylalkynes to give [Cr(CO)3(Tj -substituted-l-naphthol)] complexes indicate initial CO ligand loss to form a steady state concentration of [Cr(CO)4 C(Ph)OMe ], followed by addition of the alkynes to the metal. The subsequent rearrangements, involving attack at the carbene, to give the naphthol products are rapid. 

In 1987, Semmelhack et al. [21] published a paper concerning metal carbonyl promoted rearrangement of phenylcyclopropenes to naphthols (Scheme 17.26), which can also be classified as a [5+1] cycloaddition. The reaction can be promoted by a stoichiometric amount of Cr(CO)s or Mo (CO)5, or a catalytic amount of Mo(CO)5 but with lower yields and rates. With respect to the substrate scope, the authors found that the substituent was crucial only when was methoxy or hydrogen, the desired naphthol products can be obtained in good yields (35-78%). Otherwise, low... 

Molisch s Test. Dissolve about 01 g. of the carbohydrate in z ml. of water (for starch use 2 ml. of starch solution ), add 2-3 drops of a 1 % alcoholic solution of i-naphthol (ignoring traces of the latter precipitated by the water) and then carefully pour 2 ml. of cone. H2SO4 down the side of the test-tube so that it forms a heavy layer at the bottom. A deep violet coloration is produced where the liquids meet. This coloration is due apparently to the formation of an unstable condensation product of i-naphthol with furfural (an aldehyde produced by the dehydration of the carbohydrate). 

P-Naphthyl acetate. Dissolve 5 0 g. of p-naphthol in 25 ml. of 10 per cent, sodium hydroxide solution in a 250 ml. reagent bottle, add 60 g. of crushed ice, and 5-7 g. (5 -5 ml.) of acetic anhydride. Shake vigorously for 10-15 minutes the p-naphth acetate separates as colourless crystals. Filter with suction, wash with water, drain and dry in the air. Recrystallise from light petroleum (b.p. 60-80°) or from dilute alcohol. The yield of pure product, m.p. 71°, is 6-5 g. 

A fairly general procedure consists in coupling a phenol or naphthol with a diazotised amine, reducing the product to an aminophenol or aminonaphthol, and oxidising the hydroxy compound with acid ferric chloride solution. This method is illustrated by the preparation of (3 (or 1 2)-naphthoquinone ... 

Diazo coupling involves the N exocyclic atom of the diazonium salt, which acts as an electrophilic center. The diazonium salts of thiazoles couple with a-naphthol (605). 2-nitroresorcinol (606), pyrocatechol (607-609), 2.6-dihydroxy 4-methyl-5-cyanopyridine (610). and other heteroaromatic compounds (404. 611) (Scheme 188). The rates of coupling between 2-diazothicizolium salts and 2-naphthol-3.6-disulfonic acid were measured spectrophotometrically and found to be slower than that of 2-diazopyridinium salts but faster than that of benzene diazonium salts (561 i. The bis-diazonium salt of bis(2-amino-4-methylthiazole) couples with /3-naphthol to give 333 (Scheme 189) (612). The products obtained from the diazo coupling are usuallv highly colored (234. 338. 339. 613-616). 

Isopropylnaphthalenes can be prepared readily by the catalytic alkylation of naphthalene with propjiene. 2-lsopropylnaphthalene [2027-17-0] is an important intermediate used in the manufacture of 2-naphthol (see Naphthalenederivatives). The alkylation of naphthalene with propjiene, preferably in an inert solvent at 40—100°C with an aluminum chloride, hydrogen fluoride, or boron trifluoride—phosphoric acid catalyst, gives 90—95% wt % 2-isopropylnaphthalene however, a considerable amount of polyalkylate also is produced. Preferably, the propylation of naphthalene is carried out in the vapor phase in a continuous manner, over a phosphoric acid on kieselguhr catalyst under pressure at ca 220—250°C. The alkylate, which is low in di- and polyisopropylnaphthalenes, then is isomerized by recycling over the same catalyst at 240°C or by using aluminum chloride catalyst at 80°C. After distillation, a product containing >90 wt % 2-isopropylnaphthalene is obtained (47). 

Naphthalenesulfonic acids are important chemical precursors for dye intermediates, wetting agents and dispersants, naphthols, and air-entrainment agents for concrete. The production of many intermediates used for making a2o, a2oic, and triphenylmethane dyes (qv) involves naphthalene sulfonation and one or more unit operations, eg, caustic fusion, nitration, reduction, or amination. 

Naphthalenesulfonic Acid. The sulfonation of naphthalene with excess 96 wt % sulfuric acid at < 80°C gives > 85 wt % 1-naphthalenesulfonic acid (a-acid) the balance is mainly the 2-isomer (P-acid). An older German commercial process is based on the reaction of naphthalene with 96 wt % sulfuric acid at 20—50°C (13). The product can be used unpurifted to make dyestuff intermediates by nitration or can be sulfonated further. The sodium salt of 1-naphthalenesulfonic acid is required, for example, for the conversion of 1-naphthalenol (1-naphthol) by caustic fusion. In this case, the excess sulfuric acid first is separated by the addition of lime and is filtered to remove the insoluble calcium sulfate the filtrate is treated with sodium carbonate to precipitate calcium carbonate and leave the sodium l-naphthalenesulfonate/7J(9-/4-J7 in solution. The dry salt then is recovered, typically, by spray-drying the solution. 

Acid-cataly2ed hydroxylation of naphthalene with 90% hydrogen peroxide gives either 1-naphthol or 2-naphthiol at a 98% yield, depending on the acidity of the system and the solvent used. In anhydrous hydrogen fluoride or 70% HF—30% pyridine solution at — 10 to + 20°C, 1-naphthol is the product formed in > 98% selectivity. In contrast, 2-naphthol is obtained in hydroxylation in super acid (HF—BF, HF—SbF, HF—TaF, FSO H—SbF ) solution at — 60 to — 78°C in > 98% selectivity (57). Of the three commercial methods of manufacture, the pressure hydrolysis of 1-naphthaleneamine with aqueous sulfuric acid at 180°C has been abandoned, at least in the United States. The caustic fusion of sodium 1-naphthalenesulfonate with 50 wt % aqueous sodium hydroxide at ca 290°C followed by the neutralization gives 1-naphthalenol in a ca 90% yield. 

Naphthol is mainly used in the manufacture of the insecticide carbaryl (59), l-naphthyl A/-methyicarbamate/ iJ-2j5 - (Sevin) (22), which is produced by the reaction of 1-naphthol with methyl isocyanate. Methyl isocyanate is usually prepared by treating methylamine with phosgene. Methyl isocyanate is a very toxic Hquid, boiling at 38°C, and should not be stored for long periods of time (Bhopal accident, India). India has developed a process for the preparation of aryl esters of A/-alkyl carbamic acids. Thus l-naphthyl methylcarbamate is prepared by refluxing 1-naphthol with ethyl methylcarbamate and POCl in toluene (60). In 1992, carbaryl production totaled > 11.4 x 10 t(35). Rhc ne-Poulenc, at its Institute, W. Va., facihty is the only carbaryl producer in United States. 

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