Synthesis of aspirin without acetic anhydride

Chemicals needed

Acetyl chloride GSLEICHT.gif (932 Byte) F GSATZEND.gif (935 Byte) C     R 11-14-34    S 9-16-26-45

Methyl tert-butyl ether (MTBE) GSLEICHT.gif (932 Byte) F GSGESUND.gif (476 Byte) Xi   R 11-36/37/38    S 9-16-26-29-33-36

2-Picolin (α-)GSGESUND.gif (476 Byte) Xn    R 10-20/21/22-36/37    S 26-36

Salicylic acid GSGESUND.gif (476 Byte) Xn    R 22-36/38    S 22

Sulphuric acid 96 %  GSATZEND.gif (935 Byte) C    R 35   S (1/2)-26-30-45

Instead of 2-Picolin one can use pyridine or other methylpyridines. If one uses these purely as solvents, then these substances are often interchangeable, this must, however, be verified in the individual case.

Information concerning dangerous substances

O-Acetylsalicylic acid GSGESUND.gif (476 Byte) Xn   R 23/24/25-36/37/38    S 22-26-45-36/37/39

Aspirin is therefore harmful to one's health, according to the Aldrich cataloge even toxic (T)!

Equipment needed

Test procedure



For the synthesis of acetylsalicylic acid from salicylic, acid acetic anhydride is usually used as an acetylating agent.The increased reactivity of acetyl chloride is basically not needed here. Due to problems in the acquisition of acetic anhydride it is at a minimum of interest to hobby chemists. Picolin serves on the one hand as a solvent, on the other, however, it serves to bind the released hydrogen chloride:

o-C6H4(OH)COOH  + CH3COCl + 2-(CH3)C5H4N  -->  o-C6H4(OCOCH3) + 2-(CH3)C5H4N . HCl

salicylic acid + acetyl chloride + 2-picolin ---> O-acetylsalicylic acid + 2-picolin hydrogen chloride


Voluminous crystallization of acetylsalicylic acid


The synthesis was thought of rather spontaneously, still I will at some point try to find a useful reference in the literature.