A-Naphthaldehyde

In a 500 ml. flask, fitted with a reflux condenser, place 53 g. of 1-chloro-methylnaphthalene (Section IV.23), 84 g, of hexamethylenetetramine and 250 ml. of 1 1 acetic acid [CAUTION 1-Chloromethylnaphtha-lene and, to a lesser degree, a-naphthaldehyde have lachrymatory and vesicant properties adequate precautions should therefore be taken to avoid contact with these substances.] Heat the mixture under reflux for 2 hours it becomes homogeneous after about 15 minutes and then an oil commences to separate. Add 100 ml. of concentrated hydrochloric acid and reflux for a further 15 minutes this will hydrolyse any SchifiF s bases which may be formed from amine and aldehyde present and will also convert any amines into the ether-insoluble hydrochlorides. Cool, and extract the mixture with 150 ml. of ether. Wash the ether layer with three 50 ml. portions of water, then cautiously with 50 ml. of 10 per cent, sodium carbonate solution, followed by 50 ml. of water. Dry the ethereal solution with anhydrous magnesium sulphate, remove the ether by distillation on a steam bath, and distil the residue under reduced pressure. Collect the a-naphthaldehyde at 160-162718 mm. the yield is 38 g. 

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... 

Chapter IV. a-Chloromethylnaphthalene (IV,23) benzylamine (Gabriel synthesis) (IV,39) i r.N -dialkylanilines (from amines and trialkyl orthophosphates) (IV,42) a-naphthaldehyde (Sommelet reaction) (IV,120) a-phenyl-cinnamic acid (Perkin reaction using triethylamine) (IV,124) p-nitrostyrene (IV,129) p-bromonaphthalene and p naphthoic acid (from 2 naphthylamine-1 -sulphonic acid) (IV,62 and IV,164) diphenic acid (from phenanthrene) (IV,165). 

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°. 

To test this hypothesis, a-naphthaldehyde, which is apparently inert toward photoreduction, was irradiated in the presence of optically active 2-octanol. If a reversible hydrogen abstraction were to occur, a loss of optical activity in the 2-octanol should result. The results showed no loss in optical activity thus the question of a reversible reaction has been answered/33 ... 

On photolysis or thermolysis of the peri-methylmercapto-substituted sodium salt of a-naphthaldehyde tosyl hydrazone 77 or diazomethyl-naphthalene 78, 2//-2-methylnaphtho[frc]thiophene 80 (83JA6096) is formed in 20% yield. Ylid 79 may be a predecessor of thiophene 80. In... 

Substituted benzaldehydes and malonic acid give cinnamic acids in excellent yields. Among the common nuclear substituents are methyl, halo, " hydroxyl, methoxyl, " cyano, nitro, and diethylamino groups. Other /fi-arylacrylic acids have been made by the use of a-naphthaldehyde, phenanthraldehydes, and furfural. Phenyl-substituted aliphatic aldehydes have also been used in this condensation. ... 

In a Sommelet preparation of a-naphthaldehyde which is noteworthy because of the high yield, the entire reaction is carried out in refluxing 50% acetic acid and the quaternary salt is not isolated. At the end of the reflux period (2 hrs.), hydro-... 

---