Synthesis of acetaldehyde (ethanal)

Preparation of acetaldehyde (ethanal)

Preparation of acetaldehyde by oxidizing ethanol

Preparation of acetaldehyde by oxidizing ethanol

Preparation of acetaldehyde by oxidizing ethanol

To a 1-liter round bottom flask fitted with a dropping funnel, a distillation head with a condenser and mechanical stirrer 60 ml of concentrated sulfuric acid dissolved in 200 ml of water are placed. The diluted sulfuric acid is heated to boiling and 200 g of sodium dichromate in 200 ml of water which has been treated with 100 g of ethyl alcohol is then added in a small portion through the dropping funnel. During the addition of the sodium dichromate heat evolves and causes ebullition of the reaction mixture. The acetaldehyde, which forms during the oxidation reaction, distills into the properly cooled receiver. Besides acetaldehyde some side-reaction products such as ethyl alcohol, water, and acetal also distills. If uncondensed vapors of the acetaldehyde escape from the receiver, the addition of sodium dichromate is adjusted. Also, if boiling is not caused by the addition of  sodium dichromate, the reaction mixture is gently heated. Since the acetaldehyde cannot be obtained directly by fractional distillation, it is first converted into intermediate acetaldehyde ammonia trimer (2,4,6-trimethyl-1,3,5-triazinane), which, on proper treatment with sulfuric acid, readily yields the pure acetaldehyde.

Preparation and hydrolysis of acetaldehyde ammonia trimer (2,4,6-trimethyl-1,3,5-triazinane)

Preparation and hydrolysis of acetaldehyde ammonia trimer (2,4,6-trimethyl-1,3,5-triazinane)

Acetaldehyde ammonia trimer is prepared by absorbing acetaldehyde after distillation with ether. The ethereal solution is cooled with a freezing mixture of ice-salt, and treated with ammonia until the liquid is fully saturated. After an hour, the acetaldehyde-ammonia trimer which has separated out is collected, filtered, washed with a little ether, and dried on filter paper in a desiccator or vacuum yielding about 30 g. In order to obtain pure acetaldehyde, 10 g of acetaldehyde-ammonia trimer are dissolved in 10 ml of water. This solution is treated with a cooled mixture of 15 g of concentrated sulfuric acid and 20 ml of water, and distilled by gentle heating collecting fraction boiling at 21° C.

The practical methods of organic chemistry, by L. Gattermann, 135, 1909

Preparation of acetaldehyde from paraldehyde

Preparation of acetaldehyde from paraldehyde

Preparation of acetaldehyde from paraldehyde

For the preparation of acetaldehyde a simple fractional distillation apparatus is assembled fitted with a long all-glass Dufton column, or Hempel column. A mixture of 50 ml of paraldehyde and 0.5 ml. of concentrated sulfuric acid (as the depolymerizing agent) and a few small fragments of porous porcelain are placed in the distillation flask (the sulfuric acid may be replaced by 1-2 g of sulphamic acid (NH2SO3H) or by p-toluenesulfonic acid). The receiver is cooled in crushed ice, meanwhile, the flask is gently heated at 50-60° C, by not allowing the temperature at the head of the column to rise above 30-32° C. The distillation must be conducted very slowly in order that the fractionation may be efficient, since acetaldehyde and paraldehyde form a constant boiling point mixture, b.p. 42° C (53.4% and 46.6% respectively). Most of the acetaldehyde distils at 21-25° C and the distillation is stopped when 10 ml of liquid remain in the flask. The obtained acetaldehyde, produced in excellent yield, is sufficiently pure for many purposes, however, in order to obtain pure acetaldehyde, the product must be redistilled. Pure acetaldehyde boils at 21° C.

A text book of practical organic chemistry, by A. I. Vogel, 324-325, 1974

IUPAC Name

acetaldehyde

InChI

InChI=1S/C2H4O/c1-2-3/h2H,1H3

InChI Key

IKHGUXGNUITLKF-UHFFFAOYSA-N

Canonical SMILES

CC=O

MeSH Synonyms

Acetaldehyde, Ethanal

Depositor-Supplied Synonyms

acetaldehyde, ethanal, acetic aldehyde, ethyl aldehyde, Acetaldehyd, aldehyde, Acetylaldehyde, 75-07-0, Azetaldehyd, Aldeide acetica, Acetic ethanol, Octowy aldehyd, Aldehyde acetique, RCRA waste number U001, acetaldehydes, ethaldehyde, ethanone, Acetaldehyde (natural), NCI-C56326, NSC 7594, CCRIS 1396, HSDB 230, Acetaldehyd [German], ACETYL GROUP, CHEBI:15343, Acetaldehyde polymerized, Octowy aldehyd [Polish], UNII-GO1N1ZPR3B, UN1089, Aldeide acetica [Italian], RCRA waste no. U001, Aldehyde acetique [French], 1-oxapropylene, AI3-31167, FEMA No. 2003, IKHGUXGNUITLKF-UHFFFAOYSA-N, Acetaldehyde-d4, EINECS 200-836-8, Acetaldehyde solution, acetoaldehyde, Acetaldeyde, Aceteldehyde, Aceticaldehyde, Ethylaldehyde, acetic hydride, ethan-1-one, Aldehyde C(2), ACETALD, ACMC-20alvc, DSSTox_CID_2, QMHAIX@, CH2CHO, CH3CHO, ACETALDEHYDE, ACS, AC1Q2CBI, GO1N1ZPR3B, bmse000647, Epitope ID:145667, PS2030_SUPELCO, AC1L18NF, WLN: VH1, DSSTox_RID_79423, DSSTox_GSID_39224, KSC377C9B, BIDD:ER0621, W200298_ALDRICH, W200301_ALDRICH, W200328_ALDRICH, W200336_ALDRICH, W200344_ALDRICH, W200352_ALDRICH, W200360_ALDRICH, W200379_ALDRICH, W200387_ALDRICH, 36611_RIEDEL, 506788_SUPELCO, CHEMBL170365, GTPL6277, 00070_FLUKA, 00071_FLUKA, 36611_FLUKA, 63990_FLUKA, CHEBI:60379, CTK2H7190, HMDB00990, NSC7594, MolPort-001-783-184, LTBB001460, 402788_SIAL, NSC-7594, Tox21_202479, STL264249, AKOS000120180, LS-1654, MCULE-6800925955, RL04862, RTR-024198, UN 1089, CAS-75-07-0, NCGC00091753-01, NCGC00260028-01, 12772-68-8, AN-23835, InChI=1/C2H4O/c1-2-3/h2H,1H, Acetaldehyde [UN1089] [Flammable liquid], TR-024198, Acetaldehyde [UN1089] [Flammable liquid], FT-0621719, FT-0621749, FT-0668352, 4998-EP0930075A1, 4998-EP1441224A2, 4998-EP2269979A1, 4998-EP2269988A2, 4998-EP2269989A1, 4998-EP2269992A1, 4998-EP2270004A1, 4998-EP2270005A1, 4998-EP2270010A1, 4998-EP2270011A1, 4998-EP2270014A1, 4998-EP2270113A1, 4998-EP2270114A1, 4998-EP2272491A1, 4998-EP2272517A1, 4998-EP2272813A2, 4998-EP2272825A2, 4998-EP2272826A1, 4998-EP2272831A1, 4998-EP2272832A1, 4998-EP2272834A1, 4998-EP2272839A1, 4998-EP2272840A1, 4998-EP2272843A1, 4998-EP2272848A1, 4998-EP2272935A1, 4998-EP2272972A1, 4998-EP2272973A1, 4998-EP2275102A1, 4998-EP2275105A1, 4998-EP2275395A2, 4998-EP2275404A1, 4998-EP2275409A1, 4998-EP2275411A2, 4998-EP2275412A1, 4998-EP2277848A1, 4998-EP2277865A1, 4998-EP2277872A1, 4998-EP2277878A1, 4998-EP2277880A1, 4998-EP2280000A1, 4998-EP2280002A1, 4998-EP2280006A1, 4998-EP2280007A1, 4998-EP2280008A2, 4998-EP2280012A2, 4998-EP2281812A1, 4998-EP2281824A1, 4998-EP2284146A2, 4998-EP2284147A2, 4998-EP2284148A1, 4998-EP2284157A1, 4998-EP2284160A1, 4998-EP2286812A1, 4998-EP2286915A2, 4998-EP2287147A2, 4998-EP2287153A1, 4998-EP2287158A1, 4998-EP2287159A1, 4998-EP2287165A2, 4998-EP2287166A2, 4998-EP2289868A1, 4998-EP2289871A1, 4998-EP2289882A1, 4998-EP2289890A1, 4998-EP2289893A1, 4998-EP2289894A2, 4998-EP2292227A2, 4998-EP2292576A2, 4998-EP2292586A2, 4998-EP2292589A1, 4998-EP2292593A2, 4998-EP2292610A1, 4998-EP2292620A2, 4998-EP2295401A2, 4998-EP2295407A1, 4998-EP2295411A1, 4998-EP2295414A1, 4998-EP2295418A1, 4998-EP2295426A1, 4998-EP2295427A1, 4998-EP2295433A2, 4998-EP2295434A2, 4998-EP2295435A1, 4998-EP2295437A1, 4998-EP2295439A1, 4998-EP2298312A1, 4998-EP2298734A2, 4998-EP2298736A1, 4998-EP2298744A2, 4998-EP2298749A1, 4998-EP2298757A2, 4998-EP2298758A1, 4998-EP2298759A1, 4998-EP2298767A1, 4998-EP2298770A1, 4998-EP2298775A1, 4998-EP2298778A1, 4998-EP2298780A1, 4998-EP2298783A1, 4998-EP2299509A1, 4998-EP2301544A1, 4998-EP2301911A1, 4998-EP2301912A2, 4998-EP2301916A2, 4998-EP2301927A1, 4998-EP2301929A1, 4998-EP2301930A1, 4998-EP2301931A1, 4998-EP2301933A1, 4998-EP2301935A1, 4998-EP2301940A1, 4998-EP2302382A2, 4998-EP2302383A2, 4998-EP2305250A1, 4998-EP2305627A1, 4998-EP2305629A1, 4998-EP2305633A1, 4998-EP2305648A1, 4998-EP2305652A2, 4998-EP2305660A1, 4998-EP2305664A1, 4998-EP2305668A1, 4998-EP2305672A1, 4998-EP2305674A1, 4998-EP2305677A1, 4998-EP2305679A1, 4998-EP2305682A1, 4998-EP2305684A1, 4998-EP2305685A1, 4998-EP2305686A1, 4998-EP2305687A1, 4998-EP2305808A1, 4998-EP2305825A1, 4998-EP2308562A2, 4998-EP2308833A2, 4998-EP2308838A1, 4998-EP2308840A1, 4998-EP2308841A2, 4998-EP2308844A2, 4998-EP2308845A2, 4998-EP2308846A2, 4998-EP2308848A1, 4998-EP2308850A1, 4998-EP2308851A1, 4998-EP2308852A1, 4998-EP2308861A1, 4998-EP2308867A2, 4998-EP2308870A2, 4998-EP2308872A1, 4998-EP2308874A1, 4998-EP2308879A1, 4998-EP2308882A1, 4998-EP2308883A1, 4998-EP2308960A1, 4998-EP2311796A1, 4998-EP2311797A1, 4998-EP2311798A1, 4998-EP2311799A1, 4998-EP2311801A1, 4998-EP2311802A1, 4998-EP2311803A1, 4998-EP2311806A2, 4998-EP2311808A1, 4998-EP2311818A1, 4998-EP2311820A1, 4998-EP2311822A1, 4998-EP2311827A1, 4998-EP2311829A1, 4998-EP2311830A1, 4998-EP2311837A1, 4998-EP2311841A1, 4998-EP2311842A2, 4998-EP2314295A1, 4998-EP2314574A1, 4998-EP2314576A1, 4998-EP2314579A1, 4998-EP2314587A1, 4998-EP2316470A2, 4998-EP2316824A1, 4998-EP2316825A1, 4998-EP2316826A1, 4998-EP2316829A1, 4998-EP2316831A1, 4998-EP2316832A1, 4998-EP2316833A1, 4998-EP2316836A1, 4998-EP2316974A1, 4998-EP2371811A2, 4998-EP2371814A1, 4998-EP2372017A1, 4998-EP2374454A1, 4998-EP2374780A1, 4998-EP2374781A1, 4998-EP2374783A1, 4998-EP2374788A1, 4998-EP2377841A1, 4998-EP2377844A2, 4998-EP2380871A1, C00084, 21553-EP2287165A2, 21553-EP2314295A1, 21553-EP2314574A1, 26915-EP2280009A1, 26915-EP2305662A1, 26915-EP2308857A1, 26915-EP2314583A1, 37566-EP2277867A2, 37566-EP2280003A2, 37566-EP2281820A2, 37566-EP2284157A1, 37566-EP2286811A1, 37566-EP2287159A1, 37566-EP2292227A2, 37566-EP2298746A1, 37566-EP2298750A1, 37566-EP2298754A1, 37566-EP2298758A1, 37566-EP2298759A1, 37566-EP2298763A1, 37566-EP2298778A1, 37566-EP2305664A1, 37566-EP2305682A1, 37566-EP2308861A1, 37566-EP2308879A1, 37566-EP2311802A1, 37566-EP2311803A1, 37566-EP2311840A1, 37566-EP2374783A1, 37566-EP2377841A1, 37566-EP2377842A1, 37566-EP2380874A2, 108796-EP2277864A1, 108796-EP2280002A1, 108796-EP2298305A1, 108796-EP2298769A1, 170111-EP2275413A1, 170111-EP2287156A1, A838317, 3B4-0691, I14-6219, BRD-K77914232-001-01-3, I14-57914, I14-113209

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1 comment

  1. Fritz Haber

    I dont agree with the statement that the acetaldehyde cannot be separated via fractional destillation (” Since the acetaldehyde cannot be obtained directly by fractional distillation, it is first converted into intermediate acetaldehyde ammonia trimer (2,4,6-trimethyl-1,3,5-triazinane), which, on proper treatment with sulfuric acid, readily yields the pure acetaldehyde.”).

    Acetaldehyde forms no azeotropes with any educts or products in the first reaction. Mixtures of ethanal, acetic acid, water and other possible side products behave as zeotropic mixture. So the ethanal can be easily distilled out of the reaction mixture.

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