General Description
Liquid; colorless or pale yellow; bitter almond odor. Sinks and mixes slowly in water.
Reactivity Profile
SALICYLALDEHYDE is an aldehyde. Aldehydes are frequently involved in self-condensation or polymerization reactions. These reactions are exothermic; they are often catalyzed by acid. Aldehydes are readily oxidized to give carboxylic acids. Flammable and/or toxic gases are generated by the combination of aldehydes with azo, diazo compounds, dithiocarbamates, nitrides, and strong reducing agents. Aldehydes can react with air to give first peroxo acids, and ultimately carboxylic acids. These autoxidation reactions are activated by light, catalyzed by salts of transition metals, and are autocatalytic (catalyzed by the products of the reaction). The addition of stabilizers (antioxidants) to shipments of aldehydes retards autoxidation.
Health Hazard
LIQUID: Irritating to skin and eyes. Harmful if swallowed.
Fire Hazard
Combustible. Can react with oxidizing materials.
Chemical Properties
colourless to yellow oily liquid with a bitter almond odour
Chemical Properties
Salicylaldehyde has a pungent, irritating, bitter, almond-like odor similar to benzaldehyde, acetophenone and nitrobenzene, but with phenolic notes. It has a nut-like, coumarin flavor at low levels.
Occurrence
Occurs frequently in nature; in the flowers of Spirea ulmaria and other Spireae, in the roots of Crepis foetida L., in the fruits of Pinus avium, in the rind of Rauqolfia caffra, in the leaves of Ceanothus velutinus and in the essential oil of Cinnamomum cassia and of tobacco leaves. Also reported found in grapes, tomato, baked potato, cinnamon bark, cassia leaf, peppermint oil, pennyroyal oil, parmesan cheese, butter, milk powder, roasted chicken, beer, rum, Japanese whiskey, sherry, coffee, tea, soybean, mushroom, buckwheat, Bourbon vanilla, Chinese quince, Muscat grape, vanilla and mastic gum oil.
Uses
Salicylaldehyde is synthesized from phenol, chloroform, and
alkali according to the Reimer–Tiemman method, which was
developed in 1876.
The major uses for this chemical are perfumes, fumigants,
flavor ingredients in foods, and medicinal chemicals.
Definition
ChEBI: A hydroxybenzaldehyde carrying a hydroxy substituent at position 2.
Preparation
From phenol, chloroform and alkali according to Reimer–Tiemann method (1876); starting material for the manufacture of coumarin.
Aroma threshold values
Detection: 30 ppb
Taste threshold values
Taste characteristics at 20 ppm: spicy, medicinal and astringent
Purification Methods
It is precipitated as the bisulfite addition compound by pouring the aldehyde slowly and with stirring into a 25% solution of NaHSO3 in 30% EtOH, then standing for 30minutes. The precipitate, after filtering at the pump, and washing with EtOH, is decomposed with aqueous 10% NaHCO3, and the aldehyde is extracted into diethyl ether, dried with Na2SO4 or MgSO4, and distilled, under reduced pressure. Alternatively, salicylaldehyde is precipitated as its Cu complex by adding it to warm, saturated aqueous Cu(OAc)2, shaking and standing in ice. The precipitate is filtered off, washed with EtOH, then Et2O, and decomposed with 10% H2SO4; the aldehyde is extracted into Et2O, dried and vacuum distilled. It was also purified by dry column chromatography on Kieselgel G [Nishiya et al. J Am Chem Soc 108 3880 1986]. The acetyl derivative has m 38-39o (from pet ether or EtOH) and b 142o/18mm, 253o/atm. [Beilstein 8 IV 176.] The oxime, [94-67-7] M 137.1, crystallises CHCl3/pet ether (b 40-60o) with m 57o [Beilstein 8 IV 203.]
Waste Disposal
Salicylaldehyde is burned in a chemicalincinerator equipped with an afterburner andscrubber.
