Methyl Salicylate Oil of Wintergreen

Methyl salicylate will be prepared from salicylic acid, which is esterified at the carboxyl group with methanol. You should recall from your organic chemistry lecture course that esterification is an acid-catalyzed equilibrium reaction. The equilibrium does not lie far enough to the right to favor the formation of the ester in high yield. More product can be formed by increasing the concentrations of one of the reactants. In this experiment, a large excess of methanol will shift the equilibrium to favor a more complete formation of the ester. 

Technique 13 Physical Constants of Liquids, Part A, Boiling Points and Thermometer Correction New Technique 16 Vacuum Distillation 

Technique 25 Preparation of Samples for Spectroscopy Essay Esters—Flavors and Fragrances 

The experiment must be started at the beginning of the laboratory period because a long reflux time is needed to esterify salicylic acid and obtain a respectable yield. Perform a supplementary experiment during the reaction period or complete work that is pending from previous experiments. Enough time should remain at the end of the period to perform the extractions, place the product over the drying agent, assemble the apparatus, and perform the vacuum distillation. 

Handle the concentrated sulfuric acid carefully it can cause severe burns. 

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I. Methyl salicylate test. Heat i ml. of methanol with 0 5 g. of sodium sdicylate (or free salicylic acid) and a few drops of cone. H2SO4 gently for i minute. Cool, pour into a few ml. of cold water in a boiling-tube, and shake. Note the odour of methyl salicylate (oil of wintergreen). 

Methyl 2-hydroxybenzoate (methyl salicylate, oil of wintergreen) occurs in many plants, but it also is readily prepared synthetically by esterification of... 

Since salicylic acid has both an alcohol functional group and a carboxylic acid functional group, it can undergo two different esterification reactions depending on which functional group reacts. For example, when treated with ethanoic acid (acetic acid), salicylic acid behaves as an alcohol and the ester produced is acetylsalicylic acid (aspirin). On the other hand, when reacted with methanol, salicylic acid behaves as an acid and the ester methyl salicylate (oil of wintergreen) is produced. Methyl salicylate is also an analgesic and part of the formulation of many liniments for sore muscles. What are the structures of acetylsalicylic acid and methyl salicylate ... 

Paraamino salicylic acid has bacteriostatic activity against Mycobacterium tuberculosis. Methyl salicylate (oil of wintergreen) has been used in the past as a counterirritant. Salicylic acid (20% solution) has keratolytic properties and is used to remove comified epidermis (com). Because salicylic acid itself is too toxic for systemic use, the various salts of salicylate, including acetylsalicylic acid (aspirin), are used instead (see also Table 3). 

Salicylate poisoning or serious intoxication often occurs in children and sometimes is fatal. Salicylate intoxication should be seriously considered in any young child with coma, convulsions, or cardiovascular collapse. The fatal dose varies with the preparation. Death has followed use of 10-30 g of sodium salicylate or aspirin in adults, but larger amounts have been ingested without a fatal outcome. The lethal dose of methyl salicylate (oil of wintergreen, sweet birch oil, gaulthe-ria oil, betula oil) is considerably less than that of sodium salicylate. As little as 4 mL (4.7 g) of methyl salicylate may be fatal in children. 

Methyl Alcohol, CH3OH.—Compounds occur in certain plants from which methyl alcohol can be easily obtained in small quantities. When methyl salicylate (oil of wintergreen), which is present in checkerberries, is heated with a solution of sodium hydroxide, methyl alcohol and the sodium salt of salicylic acid are obtained. The alcohol is formed, along with other substances, when wood is subjected to destructive distillation. This method is used in the industrial preparation of methyl alcohol, which is commercially known as wood-spirit. 

Example Methyl salicylate (oil of wintergreen) in which the salicylic acid constitutes the aetive eomponent. 

A wide range of alcohols and amines can be methylated using SAM in Sj,j2 processes. For example, salicylic acid is converted to methyl salicylate (oil of wintergreen) and norepinephrine to epinephrine (adrenaline) (Figure 9.56, PNMT is the enzyme... 

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