Saligenin

In the following experiment, salicylic acid is reduced to o-hydroxybenzyl alcohol (or saligenin), which being crystalline is readily isolated the excess of hydride is destroyed by the addition of undried ether, and the aluminium hydroxide then brought into solution by the addition of sulphuric acid. 

Distil the filtered ethereal solution, using a 100 ml. flask fitted with a dropping-funnel and a side-arm for the condenser observe all the normal precautions for ether distillation (p. 162) and run the ethereal solution into the flask as fast as the ether distils over. When all the ether has distilled off, detach and cool the flask, when the oily colourless residue of saligenin will rapidly crystallise. Weight of product, 5-0 g. m.p. 75-82°. Recrystallise either from a mixture of benzene and petroleum (b.p. 60-80°), or from a minimum of water, allowing the stirred aqueous solution to cool to 65-70° before chilling. The dry crystalline saligenin has m.p. 85-86°. 

Saligenin readily sublimes when heated above its m.p., and consequently cannot be distilled. 

The main processes for the manufacture of hydroxybenzaldehydes are based on phenol. The most widely used process is the saligenin process. Saligenin (2-hydroxybenzyl alcohol [90-01-7]) and 4-hydroxybenzyl alcohol [623-05-2] are produced from base-catalyzed reaction of formaldehyde with phenol (35). Air oxidation of saligenin over a suitable catalyst such as platinium or palladium produces sahcylaldehyde (62). 

Although 4-hydroxybenzaldehyde can be made by the saligenin route, it has been made historically by the Reimer-Tiemann process, which also produces sahcylaldehyde (64). Treatment of phenol with chloroform and aqueous sodium hydroxide results in the formation of benzal chlorides, which are rapidly hydrolyzed by the alkaline medium into aldehydes. Acidification of the phenoxides results in the formation of the final products, sahcylaldehyde and 4-hydroxybenzaldehyde. The ratio of ortho and para isomers is flexible and can be controlled within certain limits. The overall reaction scheme is shown in Figure 1. Product separation is accomphshed by distillation, but this process leads to environmental problems because of the quantities of sodium chloride produced. 

Sahcyl alcohol [90-01-7] (saligenin, o-hydroxybenzyl alcohol) crystallizes from water in the form of needles or white rhombic crystals. It occurs in nature as the bitter glycoside, saUcin [138-52-3] which is isolated from the bark of Salix helix S. pentandra S. praecos some other species of willow trees, and the bark of a number of species of poplar trees such as Folpulus balsamifera P. candicans and P. nigra. 

Reactions. Saligenin [90-01-7] undergoes the typical reactions of phenols and benzyl alcohol. When heated above 100°C, it transforms into a pale yellow resinous material. Amorphous condensation products are obtained when saligenin reacts with acetic anhydride, phosphoms pentachloride, or mineral acids. Upon boiling with dilute acids, saligenin is converted into a resinous body, saliretin, a condensed form of saligenin. Condensation reactions of saligenin with itself in the absence of any catalysts and in the presence of bases have also been studied. 

Oxidation of saligenin with chromic acid or silver oxide yields saUcyladehyde as the first product. Further oxidation results in the formation of sahcyhc acid, which is also obtained when saligenin is heated with sodium hydroxide at 200—240°C. Chlorination of an aqueous solution of the alcohol gives 2,4,6-trichlorophenol, and bromination in an alkaline medium yields 2,4,6-tribromophenol and tribromosaligenin. When saligenin is heated with one mole of resorcinol in the presence of anhydrous zinc chloride, 3-hydroxyxanthene forms. 

Manufacture. The hydrolysis of the naturally occurring P-glycoside (saUcin) (8) with hydrochloric or sulfuric acid affords saligenin (9) and glucose (10) (eq. 11). 

The property of producing local anresthesia is also sho-wn by other products than alkamine esters, e.g., benzyl alcohol and its homologues, saligenin, and the esters of aminoaromatic acids such as the ethyl and diethylaminoethyl esters of 4-aminobenzoie acid. 

An in vitro study demonstrated decreased testosterone output by Leydig cells with addition of TOCP (Chapin et al. 1990), and suggested that the TOCP metabolite, saligenin cyclic-o-tolyl phosphate, may be the responsible agent for eliciting this effect. 

Salicylic alcohol glucosides, natural, 22 7 Salicyloyl chloride, 22 3 Salicylsalicylic acid, 22 16-17 physical properties of, 22 15t Saligenin, 22 23, 24 Salina salt, 5 788 Saline hydrides, 13 771 Saline solutions... 

In this class, benzaldehyde has been converted to benzyl alcohol, salicylaldehyde to saligenin, cinnamaldehyde to cinnamyl alcohol and... 

Numerous methods for the synthesis of salicyl alcohol exist. These involve the reduction of salicylaldehyde or of salicylic acid and its derivatives. The alcohol can be prepared in almost theoretical yield by the reduction of salicylaldehyde with sodium amalgam, sodium borohydride, or lithium aluminum hydride by catalytic hydrogenation over platinum black or Raney nickel or by hydrogenation over platinum and ferrous chloride in alcohol. The electrolytic reduction of salicylaldehyde in sodium bicarbonate solution at a mercury cathode with carbon dioxide passed into the mixture also yields saligenin. It is formed by the electrolytic reduction at lead electrodes of salicylic acids in aqueous alcoholic solution or sodium salicylate in the presence of boric acid and sodium sulfate. Salicylamide in aqueous alcohol solution acidified with acetic acid is reduced to salicyl alcohol by sodium amalgam in 63% yield. Salicyl alcohol forms along with -hydroxybenzyl alcohol by the action of formaldehyde on phenol in the presence of sodium hydroxide or calcium oxide. High yields of salicyl alcohol from phenol and formaldehyde in the presence of a molar equivalent of ether additives have been reported (60). Phenyl metaborate prepared from phenol and boric acid yields salicyl alcohol after treatment with formaldehyde and hydrolysis (61). 

Salix babylonica L. S. matsudana Koidz. S. microstachya Turcz. ex Trautv. Liu Ye (Weeping willow) (leaf, root) Saligenin glucoside, iodine, pyrocaledol, saponins.33 Antigoiter, antibacterial, treat tubercule bacilli. 

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