Naphthol aldehyde

This substance melts at 244° to 245° C. The corresponding products with f3-naphthol aldehyde and its methyl ether melt at 210° to 211° C. and 127° to 128° C. respectively. 

Keywords 2-naphthol, aldehyde, 1-phenyletliylamine, asymmetric aminoalkyla-tion aminoalkylnaphtliol... 

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). 

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. 

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... 

P-Naphthol-a-aldehyde (p-hydroxy-a>naphthaldehyde). Proceed as for p-resorcylaldehyde except that 20 g. of p-naphthol replaces the resor-dnol. Recrystallise the crude product (20 g.) from water with the addition of a little decolourising carbon the pure aldehyde has m.p. 80-81°. 

Sulfoalkylated naphthol compounds are effective as dispersants in aqueous cement slurries. The compounds can also be applied in an admixture with water-soluble inorganic compounds of chromium to provide additives of increased overall effectiveness. Particularly suitable are sodium chromate or ammonium dichromate. a-Naphthol is reacted in an alkaline aqueous medium with formaldehyde to create condensation products. The aldehyde can be reacted with bisulfite to produce sulfoalkylated products [1404,1410]. 

Use of benzotriazole in the preparation of diphenylmethanes and triphenylmethanes has been reviewed." Benzotriazole is condensed with an aldehyde and then allowed to react with naphthols to form a diphenyl-methane benzotriazole derivative such as 69 (Scheme 9). The benzotriazole moiety in 69 is displaced by a Grignard reagent to give triphenylmethanes.79 100 This method allows for the preparation of triarylmethanes which contain three different aromatic rings. Compounds 70-72 are prepared by this method. 

The three-component synthesis of benzo and naphthofuran-2(3H)-ones from the corresponding aromatic alcohol (phenols or naphthols) with aldehydes and CO (5 bar) can be performed under palladium catalysis (Scheme 16) [59,60]. The mechanism involves consecutive Friedel-Crafts-type aromatic alkylation and carbonylation of an intermediate benzylpalla-dium species. The presence of acidic cocatalysts such as TFA and electron-donating substituents in ortho-position (no reaction with benzyl alcohol ) proved beneficial for both reaction steps. 

This aldehyde synthesis is applicable to compounds of the aromatic series having a labile hydrogen atom (phenyl ethers,1 naphthols,2 dialkylanilines,3-4 naphthostyril,2 anthrones 2) and to certain hydrocarbons of requisite reactivity (anthracene,5-6 7 1,2-benzanthracene,6 3,4-benzpyrene,3 7 pyrene,8 styrene,9 and a, a-diarylethylenes 9). With polynuclear hydrocarbons the best results are secured by the use of a solvent such as o-dichloro-benzene. 9-Anthraldehyde has also been prepared by the action of hydrogen cyanide and aluminum chloride on anthracene in chlorobenzene.10... 

When heated with a strong acid, pentoses and hexoses are dehydrated to form furfural and hydroxymethylfurfural derivatives respectively (Figure 9.20), the aldehyde groups of which will then condense with a phenolic compound to form a coloured product. This reaction forms the basis of some of the oldest qualitative tests for the detection of carbohydrates, e.g. the Molisch test using concentrated sulphuric acid and a-naphthol. 

Catalyst 329, prepared from trimethylaluminum and 3,3/-bis(triphenylsily 1)-1,1 /-bi-2-naphthol, allowed the preparation of the endo cycloadduct (2S )-327 with 67% ee. The use of non-polar solvents raised the ee, but lowered the chemical yield213. Recently, it was reported that the reaction to form 327 exhibited autoinduction when mediated by catalyst 326214. This was attributed to a co-operative interaction of the cycloadduct with the catalyst, generating a more selective catalytic species. A wide variety of carbonyl ligands were tested for their co-operative effect on enantioselectivity. Sterically crowded aldehydes such as pivaldehyde provided the best results. Surprisingly, 1,3-dicarbonyl compounds were even more effective than monocarbonyl compounds. The asymmetric induction increased from 82 to 92% ee when di(l-adamantyl)-2,2-dimethylmalonate was added while at the same time the reaction temperature was allowed to increase by 80 °C, from -80 °C to 0°C. 

The phenolic functional group consists of a hydroxyl attached directly to a carbon atom of an aromatic ring. The OH group can also be the consequence of further oxidation or combination with other pollutants such as pesticides, aldehydes, and alcohols (i. e., 2,4-D, cyclic alcohols, cresols, naphthols, quinones, nitrophenols, and pentachlorophenol compounds) forming new more toxic compounds [17,42,160]. 

Condensation of 1-naphthol and hetaryl- or substituted-berrzaldehydes in the presence of ammonia, and subsequent acidic hydrolysis, gave 2 in moderate yields. Reactions of amino naphthols with eqrrivalent amormts of aldehydes resulted in... 

Substituted amino naphthols were synthesized with reactions of 1-naphthols and the appropriate aldehydes. Some new 2,4-disubstituted-3,4-dihydro-2/f-naphth [i,2-e][i,i]oxazines that are expected to show biological activities were obtained by the ring-closure reactions with these aminonaphthols and various aldehydes. In addition, substituted-1,3-amino-hydroxy compounds, 2, can be used in chiral ligands synthesis. 

The appropriate aromatic or heteryl- aldehyde (2 mmol freshly distilled if liquid) and 25% methanolic ammonia solution (5 mL) were added to a solution of 1-naphthol (1 mmol) in absolute MeOH (5 mL).The mixture was left to stand at ambient temperature for 2 days, during which oily products separated. The solvent was evaporated and the crade oily products were purified by column chromatography. The physical data for the compounds la-f are listed Table 39.1. 

In the reaction of 1-naphthol with 3-nitro-4-fluorobenzalmalononitrile in ethanol, catalyzed by secondary amines, nucleophilic displacement of fluorine competes with pyran ring closure. Application of a tertiary amine (N-methylmorpholine) leads to the selective formation of the corresponding aminochromene (94H(38)399). 2,3-, 1,8-Dihydrooxynaphthalenes 148 and 149 react with 1 or 2 equiv. of aromatic aldehyde 28 and MN 27a to yield naphthopyrans 150 and 151 or dipyrans 152 and 153 (90IJB885, 02RCB2238) (Scheme 53). 

Catalysis in reaction systems with undissolved substrates and products is not restricted to biocatalysis. High yields in sobd-state synthesis, sohd-to-sohd reactions, and solvent-free systems have also been reported for aldol condensation, Baeyer-Villiger oxidation, oxidative coupling of naphthols, and condensation of amines and aldehydes [1, 2]. 

Albert S.C. Chun of the Hong Kong Polytechnic University reports (J. Org. Chem. 68 1589, 2003) two important transformations. The three-component (Mannich) condensation of 10 with 11 and 12 proceeds with high diastereoselectivity, to give the amino alcohol 13. Hydroboration of the alkyne 14 followed by transmetalation of the intermediate vinyl borane gives a zinc species, which under catalysis by the easily-prepared 3-naphthol 13 adds to aromatic and branched aldehydes with high . The product allylic alcohols are useful intermediates for organic synthesis. 

Eydroxy-5,6,7,8-tetrahydro-l-napMhaldehyde was prepared [7] by the Reimer-Tiemann reaction cn 5,6,7,8-tetrahydro- 2-naphthol. Three recrystallizations from aqueous alcohol afforded a very low yield of pure aldehyde, m.p. 86-8-87-8° (spectral sample) lit. m.p. 86-87° [7J. 

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