Synthesis of salicylic acid

Preparation of salicylic acid

Preparation of salicylic acid

Preparation of salicylic acid

10 g of pure sodium hydroxide are dissolved in 15 ml of water in a metal basin, and, with stirring, 23 g of crystallised phenol are gradually added. The solution is then heated over a small free flame, with continual stirring, until a crystalline film forms on the surface of the liquid. Evaporation is continued by heating with a luminous flame kept in constant motion. During the process the basin should be securely clamped. A caked mass is obtained which is crushed at intervals with a pestle. When the mass no longer cakes together, it is transferred to a dry warm mortar and pulverised as it cools. The powder, while still warm, is quickly returned to the basin, and heated as before with thorough stirring, until it is dry enough to form dust. It is then immediately placed in a 250 ml the flask arranged for distillation, where it is heated in a bath to 140° C in a fairly rapid current of dry hydrogen obtained from a Kipp generator. When in about 1 hour no more moisture condenses in the neck of the condenser of distillation apparatus, and the body of the distillation apparatus appears dry, the mass is allowed to cool in the current of hydrogen and then, while still warm, broken up, removed, quickly powdered in a mortar, and replaced. Th object of the above operations is to obtain perfectly dry, uncharred, well-powdered sodium phenate, for it is on these factors that the success of the whole preparation depends. A moderate stream of carbon dioxide, dried through two wash bottles of conc. sulphuric acid, is passed over the surface of the sodium phenate by means of a bent tube fixed through the distillation apparatus, and terminating 1 cm. above the substance. The distillation apparatus is immersed as far as possible in the oil bath, and the temperature gradually raised to 110° C and kept there for 1 hour. The temperature is then raised to 190° C in 4 hours, and on to 200° C, where it is kept for 2 hours. During the whole, operation, the mass is stirred frequently, and the distillation apparatus also shaken from time to time, to ensure that fresh surfaces shall be exposed to the action of the gas. During the heating phenol distils and collects in the neck of the condenser while the contents darken in colour. On cooling, the phenol is melted by application of a flame to the outside of the neck and allowed to flow away; then the crude reaction product is shaken out through into a large beaker, and the distillation flask washed out several times with warm water. The whole is boiled, filtered if necessary, and treated with 100 ml conc. hydrochloric acid, cooled for some hours in ice-water, and precipitation of the crude salicylic acid facilitated by rubbing the sides of the vessel with a glass rod. The precipitate is filtered off at the pump, washed with a little cold water, and dried on a porous plate. The filtrate is evaporated to low bulk, and a little more acid obtained. It may be purified by recrystallizing from boiling water with the addition of activated charcoal, but it is better to distil the crude acid with superheated steam. The crystals are thoroughly dried, first on a porous plate, and then by heating on a water bath. They are placed in a short-necked flask and heated in an oil bath of 170° C. Then connection is made to the steam generator and a moderate current of steam at 175° C pressed in. It is important that the steam generator be not connected to the flask till the oil bath and steam have the same temperature. A wide condenser is used (width of inner tube 3 cm; of outer jacket 6 cm; length of latter 80 cm.), otherwise the condensing acid soon blocks it. The connecting tube between the flask and condenser must be 2.5 cm wide, and as short as possible. The side-piece should be near the bulb. When no more salicylic acid distils, the crystals in the condenser are added to the distillate, Which is boiled and filtered. The salicylic acid separates on cooling. The yield of salicylic acid is 60% theoretical, allowing for phenol recovered (10 g). Colourless needles; soluble in alcohol and hot water;

Systematic organic chemistry, by W. M. Cumming, 117-118, 1937.


2-hydroxybenzoic acid



InChI Key


Canonical SMILES


MeSH Synonyms

2 Hydroxybenzoic Acid, 2-Hydroxybenzoic Acid, Acid, 2-Hydroxybenzoic, Acid, o-Hydroxybenzoic, Acid, ortho-Hydroxybenzoic, Acid, Salicylic, o Hydroxybenzoic Acid, o-Hydroxybenzoic Acid, ortho Hydroxybenzoic Acid, ortho-Hydroxybenzoic Acid, Salicylic Acid

Depositor-Supplied Synonyms

salicylic acid, 2-Hydroxybenzoic acid, o-hydroxybenzoic acid, Salonil, o-Carboxyphenol, 2-Carboxyphenol, Rutranex, 69-72-7, Retarder W, Keralyt, Duoplant, Psoriacid-S-stift, Compound w, salicylate, Freezone, Saligel, Ionil, Benzoic acid, 2-hydroxy-, Stri-Dex, Salicylic acid collodion, Phenol-2-carboxylic acid, Salicylic acid soap, Trans-Ver-Sal, Verrugon, Duofil wart remover, 2-Hydroxybenzenecarboxylic acid, Orthohydroxybenzoic acid, Ionil plus, Acidum salicylicum, Dr. Scholl’s corn removers, Clear away wart remover, Domerine, Dr. Scholl’s callus removers, Salicyclic acid, Acido salicilico, Dr. Scholl’s wart remover kit, Salicylic acid, tech., Kyselina salicylova, Duofilm, Occlusal, Sebucare, Sebulex, Kyselina salicylova [Czech], Advanced pain relief corn removers, Caswell No. 731, Ionil-Plus, Advanced pain relief callus removers, Kyselina 2-hydroxybenzoova, NSC 180, Acido salicilico [Italian], Kyselina 2-hydroxybenzoova [Czech], 2-hydroxy-benzoic acid, CCRIS 6714, HSDB 672, Mediplast pads, CHEBI:16914, Hydrisalic Gel, Akurza Lotion, ortho-Hydroxybenzoic Acid, Akurza Cream, Salex Lotion, Salex Cream, Acido o-idrossibenzoico [Italian], DuoPlant Gel, Retarder SAX, AI3-02407, CHEMBL424, UNII-O414PZ4LPZ, DHS Sal Shampoo, P&S Shampoo, Salicylic acid [USAN:JAN], Salicylic acid & Sulfur Soap, EPA Pesticide Chemical Code 076602, BRN 0774890, NSC180, Phenol-2-carboxylate, Salicylic acid, tech, 2-hydroxy(1-14c)benzoic acid, phenol derivative, 7, Salicylic acid (TN), Acido o-idrossibenzoico, Spectrum_000948, K 537, AC1Q1HCK, EINECS 200-712-3, WLN: QVR BQ, SBB052826, 2-Hydroxybenzenecarboxylate, bmse000252, UPCMLD-DP126, SALICYLIC ACID, ACS, AC1Q72IF, Oprea1_040343, KBioSS_001428, Salicylic acid (6CI,8CI), Salicylic acid-ring-UL-14C, BIDD:ER0602, DivK1c_000301, Propa pH Peel-Off Acne Mask, S5922_SIGMA, S7401_SIGMA, S8519_SIGMA, W398500_ALDRICH, MLS000069653, 105910_ALDRICH, AC1L190M, SGCUT00012, UPCMLD-DP126:001, 84210_FLUKA, ATA fraction 10, ammonium salt, KBio1_000301, KBio2_001428, KBio2_003996, KBio2_006564, NINDS_000301, YGSDEFSMJLZEOE-UHFFFAOYSA-N, 27301_SIAL, 84210_SIAL, Benzoic acid, 2-hydroxy- (9CI), to_000004, 105910_SIAL, 247588_SIAL, AR-1E2203, CMC_13852, NSC629474, STK258681, AKOS000118979, DB00936, LS-2169, IDI1_000301, SMP2_000145, NCGC00159447-02, NCGC00159447-04, NCGC00159447-05, SMR000059163, AB1002436, H0206, DSSTox_CID_6368, C00805, D00097, BENZOIC ACID,2-HYDROXY SALICYLIC ACID, DSSTox_RID_78106, DSSTox_GSID_26368, I04-0192, SALICYLIC ACID (SEE ALSO ALPHA HYDROXY ACIDS), Alpha/Beta Hydroxy Acids (Glycolic Acid, Salicylic Acid), E9A559BE-383B-4F83-BC02-3031D03D558A, Acid, Salicylic, InChI=1/C7H6O3/c8-6-4-2-1-3-5(6)7(9)10/h1-4,8H,(H,9,10, ALPHA/BETA HYDROXY ACIDS (SALICYLIC ACID) (SEE ALPHA/BETA HYDROXY ACIDS), CAS-69-72-7, 29656-58-4, 7681-06-3, 8052-31-1, SAX, o Hydroxybenzoic Acid, 2 Hydroxybenzoic Acid, Acid, o-Hydroxybenzoic, Acid, 2-Hydroxybenzoic, ortho Hydroxybenzoic Acid, Acid, ortho-Hydroxybenzoic, salicylic, Salicylicacid, Durasal, Stridex, salicyhc acid, Phenolic acid, CID338, Ionil Plus shampoo, hydroxy-benzoic acid, Fostex (Salt/Mix), Pernox (Salt/Mix), Duofilm (Salt/Mix), Sebulex (Salt/Mix), Domerine (Salt/Mix), Sebucare (Salt/Mix), 2-Hydroxybenzoate, I, o-hydroxy benzoic acid, 2-hydroxy benzoic acid, Benzoic acid, hydroxy-, Salicylic acid,medicinal, ACMC-1AZIK, 63-36-5, Benzoic acid, o-hydroxy-, Epitope ID:124929, Retarder SAX (Salt/Mix), SCHEMBL1967, O414PZ4LPZ, Bazuka Extra Strength Gelreg, D020156, PHENOXY, 2-CARBOXY-, KSC203I1R, ARONIS27188, Salicylic acid (JP15/USP), Salicylic acid (JP16/USP), GTPL4306, ZINC1554, component of Tinver (Salt/Mix), BDBM26193, component of Keralyt (Salt/Mix), CTK1A3418, HMDB01895, NSC-180, MolPort-001-769-476, HMS2233A10, HMS3373M19, KUC106694N, HY-B0167, PHENYL, 3-CARBOXY-4-OXY-, Salicylic acid USP (100 micron), Tox21_113453, Tox21_201471, Tox21_303109, ANW-43703, DAP000731, DNC008510, CCG-212792, MCULE-8407868694, NE10196, RP20408, RTR-032850, NCGC00159447-06, NCGC00257065-01, NCGC00259022-01, AJ-08047, AK112186, AN-41922, BC221968, BP-12826, BT000145, KB-60386, KSC-11-207-4, OR034152, OR219977, OR254461, OR265413, OR339365, Salicylic acid & Sulfur Soap (Salt/Mix), SC-18305, TS-03583, ST2416966, TR-032850, FT-0645123, ST51046715, 3253-EP2269610A2, 3253-EP2269988A2, 3253-EP2270002A1, 3253-EP2270006A1, 3253-EP2270008A1, 3253-EP2270011A1, 3253-EP2270113A1, 3253-EP2272935A1, 3253-EP2275401A1, 3253-EP2275413A1, 3253-EP2275420A1, 3253-EP2277867A2, 3253-EP2280003A2, 3253-EP2280008A2, 3253-EP2280010A2, 3253-EP2281563A1, 3253-EP2281816A1, 3253-EP2284146A2, 3253-EP2284147A2, 3253-EP2284160A1, 3253-EP2284178A2, 3253-EP2284179A2, 3253-EP2287156A1, 3253-EP2289510A1, 3253-EP2289883A1, 3253-EP2289890A1, 3253-EP2292592A1, 3253-EP2292597A1, 3253-EP2292617A1, 3253-EP2295053A1, 3253-EP2295401A2, 3253-EP2295416A2, 3253-EP2295424A1, 3253-EP2295433A2, 3253-EP2298734A2, 3253-EP2298735A1, 3253-EP2298748A2, 3253-EP2298757A2, 3253-EP2298758A1, 3253-EP2298759A1, 3253-EP2298764A1, 3253-EP2298765A1, 3253-EP2301931A1, 3253-EP2301937A1, 3253-EP2301940A1, 3253-EP2305243A1, 3253-EP2305248A1, 3253-EP2305257A1, 3253-EP2305646A1, 3253-EP2305651A1, 3253-EP2305655A2, 3253-EP2305662A1, 3253-EP2305663A1, 3253-EP2305664A1, 3253-EP2305675A1, 3253-EP2308851A1, 3253-EP2308854A1, 3253-EP2308873A1, 3253-EP2308875A1, 3253-EP2311807A1, 3253-EP2311809A1, 3253-EP2311810A1, 3253-EP2311814A1, 3253-EP2311831A1, 3253-EP2311842A2, 3253-EP2314574A1, 3253-EP2314588A1, 3253-EP2316457A1, 3253-EP2316458A1, 3253-EP2316459A1, 3253-EP2316825A1, 3253-EP2316826A1, 3253-EP2316827A1, 3253-EP2316828A1, 3253-EP2316836A1, 3253-EP2372017A1, 3253-EP2380874A2, 44642-EP2281819A1, 44642-EP2292619A1, 44642-EP2305659A1, 44642-EP2311818A1, 197900-EP2269975A2, 197900-EP2269997A2, 197900-EP2275415A2, 3B4-0569, component of Solarcaine first aid spray (Salt/Mix), component of Fostex medicated bar and cream (Salt/Mix), 94891-34-6, 97952-82-4, Benzoicacid,2-hydroxy-,coupledwith4-amino-5-hydroxy-2,7-naphthalenedisulfonicacid,diazotized2,2′- bis[5-aminobenzenesulfonicacid]anddiazotized4-nitrobenzenamine,disodiumsalt, Benzoicacid,2-hydroxy-,coupledwithdiazotized3,3′-dimethoxy[1,1′-biphenyl]-4,4′-diamineand5,5′-[ bis ]bis[1,3-benzenediol],sodiumsalts

Removed Synonyms

Fostex, Pernox, o-Hydroxybenzoate, 2-Hydroxybenzoate, Mixture Name, Hydroxybenzoic acid, component of Tinver, Salicylic Acid-13C6, C7H6O3, K 557, Benzoic acid, 2-hydroxy-, ion(1-), CS-2007, H1342, 4-10-00-00125 (Beilstein Handbook Reference), SA, Sal, 34144-47-3

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