Naphtholic acid

Kobayashi, N. and Ando, H. (1988fc). Monoazo lake for printing inks etc.—prepared by diazotizing 2-amino-5-methyl benzenesulphonic acid, coupling with 2-hydroxy-3-naphtholic acid and adding barium chloride solution. Dainippon Inc. Patent JP63-225 667 Chem. Abstr, 110, 77504. [26It]... 

Disulpbonic and trisulphonic acids have also been prepared by action of m-diazobenzoic acid and its sulpho-acids on -naphthol-disulphonic acid. Diazoanisic acid, as ivell as the paradiazocin-namic acid and its ethers [51], gives red azo-dyes [49] ivith naphthol acid and its sulphonic acids. 

During the course of our study, we had the opportunity to evaluate the only available all aromatic, thermotropic polyester, LCP2000 from Celanese. Presumably it was a copolymer containing hydroxybenzoic (HBA) and hydroxy naphtholic acid (HNA) moieties. The sample was subjected to fiber spinnings and plastic moldings as were the thermotropic polyester-carbonates, using the same equipment and under comparable conditions. 

L where the L is of a greatly rednced charge-transfer natnre than the corresponding L state of 1-naphthol. It follows that in the case of 2-naphthol, one expects a much smaller solvent effect on the Forster-cycle acidity than the corresponding effect on 1-naphthol acidity. This indeed seems to be the case when the photoacidity of 1-naphthol and 2-naphthol was estimated from Forster-cycle calculations in water and methanol (Tables 1 and 2). 

In the subterranean parts of V. officinalis, a number of alkaloids (0.05-0.1%) occur actinidine, 8-methoxyactinidine (valerianine) and naphthyridylmethylketone have been found as well as several other, yet unidentified alkaloids. Furthermore, isoferulic acid, y- aminobutyric acid, free fatty acids and short-chain carboxylic acids have been isolated. In the leaves of V officinalis, the presence of four flavonoids has also been demonstrated. From the subterranean parts of V. jatamansi, isomers of lanarin isovalerate and 4-methoxy-8-pentyl-l- naphtholic acid were isolated and characterized [50, 51]. 

The strategy incorporated methyl isocoumarin (132) as the starting point and then focussed attention to built the naphtholic acid intermediate [104] (135). Its subsequent transformation into the diacid (136) was efficiently formulated with LDA and diethylcarbonate followed by the preparation of isocoumarin (137) (Scheme 26). The annulation of 137 into 138 gave unexpected difficulties. For example, treatment of 137 with ethanolamine in refluxing ethanol formed 139 as a sole product. We believe that mechanistically the formation of 139 occurs through 138. In order to terminate this reaction at this stage of 138, a host of reaction conditions were tried. Fortunately, treatment... 

As for nematic phases, if the pendant group occupies a recess in the structure such that its full broadening effect is not operative, an increase in Sc thermal stability can arise, e.g. in 5-subsitututed 6- -alkoxy-2-naphtholic acids. The increase in T[Sc N] is larger than that for T[N->I], showing again that dipole interactions play a role in enhancing the thermal stability of the Sc transition. 

Molisch s test A general test for carbohydrates. The carbohydrate is dissolved in water, alcoholic 1-naphthol added, and concentrated sulphuric acid poured down the side of the tube. A deep violet ring is formed at the junction of the liquids. A modification, the rapid furfural test , is used to distinguish between glucose and fructose. A mixture of the sugar, 1-naphthol, and concentrated hydrochloric acid is boiled. With fructose and saccharides containing fructose a violet colour is produced immediately the solution boils. With glucose the appearance of the colour is slower. 

Schaffer s acid, CioHg04S. 2-hydroxy-7-naphthalene sulphonic acid. Obtained by sulphonating 2-naphthol with a small amount of sulphuric acid at a higher temperature than is used for the preparation of crocein acid. A valuable dyestuff intermediate. 

Required Aniline, 4-5 ml. hydrochloric acid, icml. sodium nitrite, 4 g. 2-naphthol, 7 g. 

Dissolve 4 5 ml. of aniline in a mixture of 10 ml. of concentrated hydrochloric acid and 20 ml. of water cool the solution to 5°, and diazotise by the addition of 4 g. of sodium nitrite dissolved in 20 ml, of water, observing the usual precautions given on page 181. Dissolve 7 g. of 2-naphthol in 60 ml. of 10% sodium hydroxide solution contained in a 200 ml. beaker, and cool this solution to 5 by external cooling, aided by the direct addition of about 20-30 g. of crushed ice. Now add the diazotised solution very slowly to the naphthol solution, keeping the latter well stirred meanwhile the mixed solutions immediately develop a deep red colour, and the benzeneazonaphthol should... 

Required Benzeneazo-naphthol from above experiment methylated spirit, 100 ml. stannous chloride, 22 g. hydrochloric acid, 60 ml. 

Add dil. H2SO4 until the solution is acid to litmus. Cool, and scratch the sides of the vessel with a glass rod a white precipitate indicates an aromatic carboxylic acid or uric acid, or a solid phenol insoluble in water (e.g., i- or 2-naphthol). If a precipitate is obtained, filter off through a Buchner funnel, wash with water, recrystallise if necessary and identify. 

Almost insoluble in cold water. Higher alcohols (including benzyl alcohol), higher phenols (e.g., naphthols), metaformaldehyde, paraldehyde, aromatic aldehydes, higher ketones (including acetophenone), aromatic acids, most esters, ethers, oxamide and domatic amides, sulphonamides, aromatic imides, aromatic nitriles, aromatic acid anhydrides, aromatic acid chlorides, sulphonyl chlorides, starch, aromatic amines, anilides, tyrosine, cystine, nitrocompounds, uric acid, halogeno-hydrocarbons, hydrocarbons. 

Dilute sodium hydroxide solution (and also sodium carbonate solution and sodium bicarbonate solution) can be employed for the removal of an organic acid from its solution in an organic solvent, or for the removal of acidic impurities present in a water-insoluble solid or liquid. The extraction is based upon the fact that the sodium salt of the acid is soluble in water or in dilute alkali, but is insoluble in the organic solvent. Similarly, a sparingly soluble phenol, e.g., p-naphthol, CioH,.OH, may be removed from its solution in an organic solvent by treatment with sodium hydroxide solution. 

If time permits, carry out similar experiments with benzoic acid (122°) and -naphthol (123°). 

Picrates of p-naphthyl alkyl ethers. Alkyl halides react with the sodium or potassium derivative of p-naphthol in alcoholic solution to yield the corresponding alkyl p-naphthyl ethers (which are usually low m.p. solids) and the latter are converted by alcoholic picric acid into the crystalline picrates ... 

Mix together 1 0 g. of pure p-naphthol and the theoretical quantity of 50 per cent, potassium hydroxide solution, add 0-5 g. of the halide, followed by sufficient rectified spirit to produce a clear solution. For alkyl chlorides, the addition of a little potassium iodide is recommended. Heat the mixture under reflux for 15 minutes, and dissolve any potassium halide by the addition of a few drops of water. The p-naphthyl ether usually crystallises out on cooling if it does not, dilute the solution with 10 per cent, sodium hydroxide solution untU precipitation occurs. Dissolve the p-naphthyl ether in the minimum volume of hot alcohol and add the calculated quantity of picric acid dissolved in hot alcohol. The picrate separates out on cooling. Recrystallise it from rectified spirit. 

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

By condensation of diazotised sulphanilic acid with p-naphthol in the presence of sodium hydroxide, the useful dyestuff Orange II (p-sulphobenzene-azo-3-naphthol) is obtained ... 

It is interesting to note that azo dyestuffs may be conveniently reduced either by a solution of stannous chloride in hydrochloric acid or by sodium hyposulphite. Thus phenyl-azo-p-naphthol 3delds both aniline and a-amino-p-naphthol (see formula above), and methyl orange gives p-aminodimethylaniline and sulphanilic acid ... 

P-Hydroxy-a-naphthaldehyde, Equip a 1 litre three-necked flask with a separatory funnel, a mercury-sealed mechanical stirrer, and a long (double surface) reflux condenser. Place 50 g. of p-naphthol and 150 ml. of rectified spirit in the flask, start the stirrer, and rapidly add a solution of 100 g. of sodium hydroxide in 210 ml. of water. Heat the resulting solution to 70-80° on a water bath, and place 62 g. (42 ml.) of pure chloroform in the separatory funnel. Introduce the chloroform dropwise until reaction commences (indicated by the formation of a deep blue colour), remove the water bath, and continue the addition of the chloroform at such a rate that the mixture refluxes gently (about 1 5 hours). The sodium salt of the phenolic aldehyde separates near the end of the addition. Continue the stirring for a further 1 hour. Distil off the excess of chloroform and alcohol on a water bath use the apparatus shown in Fig. II, 41, 1, but retain the stirrer in the central aperture. Treat the residue, with stirring, dropwise with concentrated hydrochloric acid until... 

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 ... 

Treatment of a solution of sodium nitrite and the sodium salt of p-naphthol with sulphuric acid gives an excellent jdeld of a-nitroso- p-naphthol ... 

Dissolve 100 g. of p-naphthol (Section IV,102) in a warm solution of 28 g. of sodium hydroxide in 1200 ml. of water contained in a 2-5 htre round-bottomed or bolt-head flask fitted with a mechanical stirrer. Cool the solution to 0° in a bath of ice and salt, and add 50 g. of powdered sodium nitrite. Start the stirrer and add, by means of a separatory funnel supported above the flask, 220 g. (166-5 ml.) of sulphuric acid (sp. gr. 1 32) at such a rate that the whole is added during 90 minutes... 

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