# Chloral

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Chloral Chloral Chloral Names Preferred IUPAC name Trichloroacetaldehyde Other names Trichloroethanal Identifiers CAS Number 75-87-6 Y 3D model (JSmol) Interactive image Beilstein Reference 506422 ChEBI CHEBI:48814 ChEMBL ChEMBL27551 ChemSpider 6167 Y DrugBank DB02650 ECHA InfoCard 100.000.829 EC Number 200-911-5 KEGG C14866 Y PubChem CID 6407 UNII FLI06WS32H Y CompTox Dashboard (EPA) DTXSID7024744 InChI InChI=1S/C2HCl3O/c3-2(4,5)1-6/h1H Key: HFFLGKNGCAIQMO-UHFFFAOYSA-N SMILES ClC(Cl)(Cl)C=O Properties Chemical formula C2HCl3O Molar mass 147.38 g·mol−1 Appearance Colorless liquid Odor Pungent and irritating Density 1.404 g/cm3 Melting point −57.5 °C (−71.5 °F; 215.7 K) Boiling point 97.8 °C (208.0 °F; 370.9 K) Solubility in water Forms soluble hydrate Solubility in ethanol Miscible Solubility in diethyl ether Miscible Solubility in chloroform Miscible Acidity (pKa) 9.66 Magnetic susceptibility (χ) −6.77×10−5 cm3/mol Refractive index (nD) 9.48846 Hazards GHS labelling: Pictograms Signal word Danger Hazard statements H301, H302, H315, H319, H335 Precautionary statements P261, P264, P270, P271, P280, P301+P310, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501 Lethal dose or concentration (LD, LC): LD50 (median dose) 480 mg/kg (rat, oral) Related compounds Related compounds Fluoral, Bromal, Iodal Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Chemical compound

**Chloral**, also known as **trichloroacetaldehyde** or **trichloroethanal**, is the [organic compound](/source/Organic_compound) with the formula Cl3CCHO. This [aldehyde](/source/Aldehyde) is a colourless liquid that is soluble in a wide range of solvents. It reacts with water to form [chloral hydrate](/source/Chloral_hydrate), a once widely used [sedative](/source/Sedative) and [hypnotic](/source/Hypnotic) substance.[1]

## Production

Chloral was first prepared, and named, by the German chemist [Justus von Liebig](/source/Justus_von_Liebig) in 1832.[2] Liebig treated anhydrous ethanol with dry chlorine gas.[3]

Chloral is produced commercially by the chlorination of [acetaldehyde](/source/Acetaldehyde) in the presence of hydrochloric acid, producing [chloral hydrate](/source/Chloral_hydrate). Ethanol can also be used as a feedstock. This reaction is catalyzed by [antimony trichloride](/source/Antimony_trichloride):

- H3CCHO + 3 Cl2 + H2O → Cl3CCH(OH)2 + 3 HCl

The chloral hydrate is distilled from the reaction mixture. The distillate is then dehydrated with concentrated [sulfuric acid](/source/Sulfuric_acid), after which the heavier acid layer (containing the water) is drawn off:

- Cl3CCH(OH)2 → Cl3CCHO + H2O

The resulting product is purified by fractional distillation.[4] Small amounts of chloral hydrate occur in some chlorinated water.

## Key reactions

Chloral tends to form [adducts](/source/Adduct) with water (to give [chloral hydrate](/source/Chloral_hydrate)) and alcohols.

Aside from its tendency to hydrate, chloral is notable as a building block in the synthesis of [DDT](/source/DDT). For this purpose, chloral is treated with [chlorobenzene](/source/Chlorobenzene) in the presence of a catalytic amount of [sulfuric acid](/source/Sulfuric_acid):

- Cl3CCHO + 2 C6H5Cl → Cl3CCH(C6H4Cl)2 + H2O

This reaction was described by [Othmar Zeidler](/source/Othmar_Zeidler) in 1874.[5] The related herbicide [methoxychlor](/source/Methoxychlor) is also produced from chloral.

Treating chloral with [sodium hydroxide](/source/Sodium_hydroxide) gives [chloroform](/source/Chloroform) Cl3CH and [sodium formate](/source/Sodium_formate) HCOONa.

- Cl3CCHO + NaOH → Cl3CH + HCOONa

Chloral is easily reduced to [trichloroethanol](/source/Trichloroethanol), which is produced in the body from chloral.[4]

## Toxicity

Chloral and [chloral hydrate](/source/Chloral_hydrate) have the same properties biologically since the former hydrates rapidly. Chloral hydrate was routinely administered to patients on the gram scale with no lasting effects. Prolonged exposure to the vapors is toxic with a [LC50](/source/LC50) for 4-hour exposure of 440 mg/m3.[4]

## See also

- [Chloral cyanohydrin](/source/Chloral_cyanohydrin)

- [Chloroacetaldehyde](/source/Chloroacetaldehyde)

- [Dichloroacetaldehyde](/source/Dichloroacetaldehyde)

- [Fluoral](/source/Fluoral)

- [Bromal](/source/Bromal)

- [Iodal](/source/Iodal)

## References

1. **[^](#cite_ref-1)** Luknitskii, F. I. (1975). "Chemistry of Chloral". *Chemical Reviews*. **75** (3): 259–289. [doi](/source/Doi_(identifier)):[10.1021/cr60295a001](https://doi.org/10.1021%2Fcr60295a001).

1. **[^](#cite_ref-2)** See: - Liebig, Justus (1832). ["Ueber die Verbindungen, welche durch die Einwirkung des Chlors auf Alkohol, Aether, ölbildendes Gas und Essiggeist entstehen"](https://babel.hathitrust.org/cgi/pt?id=uva.x002457883&view=1up&seq=190) [On the compounds which arise by the reaction of chlorine with alcohol [ethanol], ether [diethyl ether], oil-forming gas [ethylene], and spirit of vinegar [acetone]]. *Annalen der Pharmacie* (in German). **1** (2): 182–230. [doi](/source/Doi_(identifier)):[10.1002/jlac.18320010203](https://doi.org/10.1002%2Fjlac.18320010203). pp. 189–191 *"Wirkung des Chlors auf Alkohol"* [Reaction of Chlorine with alcohol [i.e., ethanol]]; pp. 191–194 *"Darstellung des Chloral[s]"* [Preparation of chloral]; pp. 195–198 *"Eigenschaften des Chlorals"* [Properties of chloral]. Liebig named chloral on p. 191. From p. 191: *"Ich werde in dem Folgenden zeigen, dass bei einer vollkommnen Zersetzung des Alkohols das Chlor den Wasserstoff desselben abscheidet und diesen Wasserstoff ersetzt; es entsteht eine neue eigenthümliche Verbindung von Chlor, Kohlenstoff und Sauerstoff, welche ich, indem ich keinen zweckmässigeren Namen weiss, vorläufig Chloral nenne. Dieser Name ist dem Worte Aethal nachgebildet."* (In the following, I will show that during a complete breakdown of ethanol, chlorine removes its [i.e., ethanol's] hydrogen and replaces this hydrogen; there arises a strange new compound of chlorine, carbon, and oxygen, which I — as I know no more appropriate name — provisionally name "chloral". This name is patterned after the word *Aethal* [i.e., ethyl].) - Reprinted in: Liebig, Justus (1832). ["Ueber die Verbindungen, welche durch die Einwirkung des Chlors auf Alkohol, Aether, ölbildendes Gas und Essiggeist entstehen"](https://babel.hathitrust.org/cgi/pt?id=wu.89048351662&view=1up&seq=861) [On the compounds which arise by the reaction of chlorine with alcohol [ethanol], ether [diethyl ether], oil-forming gas [ethylene], and spirit of vinegar [acetone]]. *Annalen der Physik und Chemie*. 2nd series (in German). **24** (2): 243–295. [Bibcode](/source/Bibcode_(identifier)):[1832AnP...100..243L](https://ui.adsabs.harvard.edu/abs/1832AnP...100..243L). [doi](/source/Doi_(identifier)):[10.1002/andp.18321000206](https://doi.org/10.1002%2Fandp.18321000206). pp. 250-252 *"Wirkung des Chlors auf Alkohol"* [Reaction of Chlorine with alcohol [i.e., ethanol]]; pp. 252–255 *"Darstellung des Chloral[s]"* [Preparation of chloral]; pp. 255–259 *"Eigenschaften des Chlorals"* [Properties of chloral]. - Gmelin, Leopold, ed. (1848). [*Handbuch der Chemie*](https://babel.hathitrust.org/cgi/pt?id=mdp.39015076005811&view=1up&seq=909) (in German). Vol. 4 (4th ed.). Heidelberg, [Germany]: Karl Winter. pp. 893–897.

1. **[^](#cite_ref-3)** Liebig passed dry chlorine gas through anhydrous ethanol for 11–13 days, until hydrogen chloride ceased to form. The product was dried by shaking with concentrated sulfuric acid, decanted over chalk, and then distilled. (Liebig, 1832), pp. 191–194.

1. ^ [***a***](#cite_ref-Ull_4-0) [***b***](#cite_ref-Ull_4-1) [***c***](#cite_ref-Ull_4-2) Jira, Reinhard; Kopp, Erwin; McKusick, Blaine C.; Röderer, Gerhard; Bosch, Axel; Fleischmann, Gerald. "Chloroacetaldehydes". *[Ullmann's Encyclopedia of Industrial Chemistry](/source/Ullmann's_Encyclopedia_of_Industrial_Chemistry)*. Weinheim: Wiley-VCH. [doi](/source/Doi_(identifier)):[10.1002/14356007.a06_527.pub2](https://doi.org/10.1002%2F14356007.a06_527.pub2). [ISBN](/source/ISBN_(identifier)) [978-3-527-30673-2](https://en.wikipedia.org/wiki/Special:BookSources/978-3-527-30673-2).

1. **[^](#cite_ref-5)** Zeidler, Othmar (1874). ["Verbindungen von Chloral mit Brom- und Chlorbenzol"](http://babel.hathitrust.org/cgi/pt?id=uiug.30112025694776;view=1up;seq=231) [Compounds of chloral with bromo- and chlorobenzene]. *Berichte der Deutschen Chemischen Gesellschaft*. **7** (2): 1180–1181. [doi](/source/Doi_(identifier)):[10.1002/cber.18740070278](https://doi.org/10.1002%2Fcber.18740070278).

v t e GABAA receptor positive modulators Alcohols Brometone Butanol Chloralodol Chlorobutanol (cloretone) Ethanol (alcohol) (alcoholic drink) Ethchlorvynol Isobutanol Isopropanol Menthol Methanol Methylpentynol Pentanol Petrichloral Propanol tert-Butanol (2M2P) tert-Pentanol (2M2B) Tribromoethanol Trichloroethanol Triclofos Trifluoroethanol Barbiturates (-)-DMBB Allobarbital Alphenal Amobarbital Aprobarbital Barbexaclone Barbital Benzobarbital Benzylbutylbarbiturate Brallobarbital Brophebarbital Butabarbital/Secbutabarbital Butalbital Buthalital Butobarbital Butallylonal Carbubarb Crotylbarbital Cyclobarbital Cyclopentobarbital Difebarbamate Enallylpropymal Ethallobarbital Eterobarb Febarbamate Heptabarb Heptobarbital Hexethal Hexobarbital Methallatal Metharbital Methitural Methohexital Methylphenobarbital Narcobarbital Nealbarbital Pentobarbital Phenallymal Phenobarbital Phetharbital Primidone Probarbital Propallylonal Propylbarbital Proxibarbital Reposal Secobarbital Sigmodal Spirobarbital Talbutal Tetrabamate Tetrabarbital Thialbarbital Thiamylal Thiobarbital Thiobutabarbital Thiopental Thiotetrabarbital Valofane Vinbarbital Vinylbital Benzodiazepines 2-Oxoquazepam 3-Hydroxyphenazepam Adinazolam Alprazolam Arfendazam Avizafone Bentazepam Bretazenil Bromazepam Bromazolam Brotizolam Camazepam Carburazepam Chlordiazepoxide Ciclotizolam Cinazepam Cinolazepam Clazolam Climazolam Clobazam Clonazepam Clonazolam Cloniprazepam Clorazepate Clotiazepam Cloxazolam CP-1414S Cyprazepam Delorazepam Demoxepam Diazepam Diclazepam Dimdazenil Doxefazepam Elfazepam Estazolam Ethyl carfluzepate Ethyl dirazepate Ethyl loflazepate Etizolam FG-8205 Fletazepam Flubromazepam Flubromazolam Fludiazepam Flunitrazepam Flunitrazolam Flurazepam Flutazolam Flutemazepam Flutoprazepam Fosazepam Gidazepam Halazepam Haloxazolam Iclazepam Imidazenil Irazepine Ketazolam Lofendazam Lopirazepam Loprazolam Lorazepam Lormetazepam Meclonazepam Medazepam Menitrazepam Metaclazepam Mexazolam Midazolam Motrazepam N-Desalkylflurazepam Nifoxipam Nimetazepam Nitrazepam Nitrazepate Nitrazolam Nordazepam Nortetrazepam Oxazepam Oxazolam Phenazepam Pinazepam Pivoxazepam Prazepam Premazepam Proflazepam Pyrazolam QH-II-66 Quazepam Reclazepam Remimazolam Rilmazafone Ripazepam Ro48-6791 Ro48-8684 SH-053-R-CH3-2′F Sulazepam Temazepam Tetrazepam Tolufazepam Triazolam Triflubazam Triflunordazepam (Ro5-2904) Tuclazepam Uldazepam Zapizolam Zolazepam Zomebazam Carbamates Carisbamate Carisoprodol Clocental Cyclarbamate Difebarbamate Emylcamate Ethinamate Febarbamate Felbamate Hexapropymate Hydroxyphenamate Lorbamate Mebutamate Meprobamate Nisobamate Pentabamate Phenprobamate Procymate Styramate Tetrabamate Tybamate Flavonoids 6-Methylapigenin Ampelopsin (dihydromyricetin) Apigenin Baicalein Baicalin Catechin EGC EGCG Hispidulin Linarin Luteolin Rc-OMe Skullcap constituents (e.g., baicalin) Wogonin Imidazoles Etomidate Metomidate Methoxyetomidate Propoxate Isopropoxate Butomidate Iso-butomidate Sec-butomidate CF2-Etomidate CF3-Etomidate CF3-Propoxate Flutomidate 2,6-Dichloro-3-fluoroetomidate Kava constituents 10-Methoxyyangonin 11-Methoxyyangonin 11-Hydroxyyangonin Desmethoxyyangonin 11-Methoxy-12-hydroxydehydrokavain 7,8-Dihydroyangonin Kavain 5-Hydroxykavain 5,6-Dihydroyangonin 7,8-Dihydrokavain 5,6,7,8-Tetrahydroyangonin 5,6-Dehydromethysticin Methysticin 7,8-Dihydromethysticin Yangonin Monoureides Acecarbromal Apronal (apronalide) Bromisoval Carbromal Capuride Ectylurea Neurosteroids Acebrochol Allopregnanolone (brexanolone) Alfadolone Alfaxalone 3α-Androstanediol Androstenol Androsterone Certain anabolic-androgenic steroids Cholesterol Cortisol (hydrocortisone) DHDOC 3α-DHP 5α-DHP 5β-DHP DHT Etiocholanolone ETX-155 Ganaxolone Hydroxydione LPCN-1154 Minaxolone NORA-520 ORG-20599 ORG-21465 P1-185 Posovolone PRAX-114 Pregnanolone (eltanolone) Progesterone Renanolone SAGE-105 SAGE-324 SAGE-516 SAGE-689 SAGE-872 Testosterone THDOC Zuranolone Nonbenzodiazepines Cyclopyrrolones: Eszopiclone Pagoclone Pazinaclone Suproclone Suriclone Zopiclone Imidazopyridines: Alpidem DS-1 Necopidem Saripidem Zolpidem Pyrazolopyrimidines: Divaplon Fasiplon Indiplon Lorediplon Ocinaplon Panadiplon Taniplon Zaleplon Others: Adipiplon AXS-17 (BAER-101, AZD-7325) CGS-8216 CGS-9896 CGS-13767 CGS-20625 CL-218,872 CP-615,003 CTP-354 ELB-139 GBLD-345 Imepitoin JM-1232 L-838,417 Lirequinil (Ro41-3696) Miltirone (rosmariquinone) NS-2664 NS-2710 NS-11394 NS-11821 Pipequaline ROD-188 RWJ-51204 SB-205,384 SX-3228 TGSC01AA TP-003 TPA-023 TP-13 U-89843A U-90042 Viqualine Y-23684 Phenols Cipepofol Fospropofol Propofol Propofol hemisuccinate Thymol Piperidinediones Glutethimide Methyprylon Piperidione Pyrithyldione Pyrazolopyridines Cartazolate Etazolate ICI-190,622 Tracazolate Quinazolinones Afloqualone Cloroqualone Diproqualone Etaqualone Mebroqualone Mecloqualone Methaqualone Methylmethaqualone Nitromethaqualone SL-164 Volatiles/gases Acetone Acetophenone Acetylglycinamide chloral hydrate Aliflurane Benzene Butane Butylene Centalun Chloral Chloral betaine Chloral hydrate Chloroform Cryofluorane Desflurane Dichloralphenazone Dichloromethane Diethyl ether Enflurane Ethyl chloride Ethylene Fluroxene Gasoline Halopropane Halothane Isoflurane Kerosine Methoxyflurane Methoxypropane Nitric oxide Nitrogen Nitrous oxide Norflurane Paraldehyde Propane Propylene Roflurane Sevoflurane Synthane Teflurane Toluene Trichloroethane (methyl chloroform) Trichloroethylene Vinyl ether Others/unsorted 3-Hydroxybutanal α-EMTBL AA-29504 Alogabat Avermectins (e.g., ivermectin) Bromide compounds (e.g., lithium bromide, potassium bromide, sodium bromide) Carbamazepine Chloralose Chlormezanone Clomethiazole Darigabat DEABL Deuterated etifoxine Dihydroergolines (e.g., dihydroergocryptine, dihydroergosine, dihydroergotamine, ergoloid (dihydroergotoxine)) DS2 Efavirenz Etazepine Etifoxine Fenamates (e.g., flufenamic acid, mefenamic acid, niflumic acid, tolfenamic acid) Fluoxetine Flupirtine Hopantenic acid KRM-II-81 Lanthanum Lavender oil Lignans (e.g., 4-O-methylhonokiol, honokiol, magnolol, obovatol) Loreclezole Menthyl isovalerate (validolum) Monastrol Nezavist (DCUK-Oet) Nicotinic acid Nicotinamide NTX-1955 (RO-7308480) Org 25,435 Phenytoin Propanidid Retigabine (ezogabine) Safranal Seproxetine Stiripentol Sulfonylalkanes (e.g., sulfonmethane (sulfonal), tetronal, trional) Terpenoids (e.g., borneol) Topiramate Valerian constituents (e.g., isovaleric acid, isovaleramide, valerenic acid, valerenol) Unsorted benzodiazepine site positive modulators: α-Pinene MRK-409 (MK-0343) TCS-1105 TCS-1205 See also: Receptor/signaling modulators • GABA receptor modulators • GABA metabolism/transport modulators

Authority control databases: National Japan

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Adapted from the Wikipedia article [Chloral](https://en.wikipedia.org/wiki/Chloral) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Chloral?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.