chloral

Structural formula
General
Surname	chloral
other names	Trichloroacetaldehyde; Trichloroethanal;
Molecular formula	C 2 HCl 3 O
Brief description	colorless, oily liquid with a pungent odor
External identifiers / databases
EC number	200-911-5
ECHA InfoCard	100,000,829
PubChem	6407
ChemSpider	13863645
DrugBank	DB02650
Wikidata	Q422755
properties
Molar mass	147.39 g mol −1
Physical state	liquid
density	1.515 g cm −3 (20 ° C)
Melting point	−57.5 ° C
boiling point	97.8 ° C
Vapor pressure	52 h Pa (20 ° C)
solubility	miscible with water to form chloral hydrate
Refractive index	1.4580 (20 ° C)
safety instructions
GHS labeling of hazardous substances danger
H and P phrases	H: 301-315-319
	P: 301 + 310-305 + 351 + 338
Thermodynamic properties
ΔH f 0	−234.5 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Chloral or trichloroacetaldehyde is a chemical compound from the group of aldehydes . It is next to the monochloroacetaldehyde and Dichloroacetaldehyde one of three possible chlorinated acetaldehyde.

Presentation and extraction

The industrial production of chloral takes place through the chlorination of acetaldehyde .

{\ displaystyle \ mathrm {CH_ {3} CHO + 3 \, Cl_ {2} \ rightarrow CCl_ {3} CHO + 3 \, HCl}}

The synthesis can also start from ethanol . A correspondingly higher amount of chlorine is required to oxidize the ethanol to acetaldehyde as an intermediate.

{\ displaystyle \ mathrm {CH_ {3} CH_ {2} OH + 4 \, Cl_ {2} \ rightarrow CCl_ {3} CHO + 5 \, HCl}}

properties

In its pure form, it is an oily, colorless liquid that boils at 97.8 ° C under normal pressure . According to Antoine, the vapor pressure function results from log ₁₀ (P) = A− (B / (T + C)) (P in Torr, T in ° C) with A = 4,32856, B = 1466,442 and C = - 31,765 in the temperature range from 235 to 370 K. Chloral vapors are heavier than air. As soon as chloral comes into contact with water, chloral hydrate , an aldehyde hydrate, is formed . This is a stable geminal diol. This is one of the few compounds that contradicts the Erlenmeyer rule . The conversion to chloral hydrate proceeds exothermically with a heat of reaction of −51.76 kJ mol ⁻¹ .

{\ displaystyle \ mathrm {CCl_ {3} CHO + H_ {2} O \ rightarrow CCl_ {3} CH (OH) _ {2}}}

The corresponding hemiacetals are formed with alcohols.

{\ displaystyle \ mathrm {CCl_ {3} CHO + ROH \ rightarrow CCl_ {3} CH (OH) OR}}

The base-catalyzed condensation reactions typical for aldehydes are not possible with chloral. Here, the action of bases causes the CC bond to be cleaved with the formation of chloroform .

{\ displaystyle \ mathrm {CCl_ {3} CHO + NaOH \ rightarrow CHCl_ {3} + HCO_ {2} Na}}

{\ displaystyle \ mathrm {CCl_ {3} CHO + R_ {2} NH \ rightarrow CHCl_ {3} + HCONR_ {2} (R = alkyl)}}

use

The compound is a raw material for the production of chloral hydrate and pesticides such as B. DDT .

toxicology

Chloral and concentrated chloral solutions can cause burns to the skin and mucous membranes . Chloral solutions with more than 10 to 15% cause skin sensitization in humans . Inhaling chloral vapors leads to dry coughs and attacks of suffocation. In severe cases, the entire respiratory tract can be damaged; some time after contact with chloral vapors, toxic pulmonary edema can also occur. Chloral can have allergenic effects in the airways .

Web links

Chloral hydrate and chloral . In: Merck's Warenlexikon . 3rd ed. 1884 ff., P. 80 f.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Entry on chloral in the GESTIS substance database of the IFA , accessed on December 18, 2015(JavaScript required) .
↑ ^a ^b ^c Entry on chloral. In: Römpp Online . Georg Thieme Verlag, accessed on May 18, 2016.
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-490.
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-21.
↑ ^a ^b ^c ^d R. Jira, E. Kopp, BC McKusick, G. Röderer, A. Bosch, G. Fleischmann: Chloroacetaldehydes. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag, Weinheim 2012, doi : 10.1002 / 14356007.a06_527.pub2 .
^ DR Stull: Vapor Pressure of Pure Substances. Organic and Inorganic Compounds. In: Ind. Eng. Chem. 39, 1947, pp. 517-540, doi: 10.1021 / ie50448a022 .
^ KB Wiberg, KM Morgan, H. Maltz: Thermochemistry of carbonyl reactions. 6. A study of hydration equilibria. In: J. Am. Chem. Soc. 116, 1994, pp. 11067-11077, doi: 10.1021 / ja00103a024 .

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f Entry on chloral in the GESTIS substance database of the IFA , accessed on December 18, 2015(JavaScript required) .

[Roempp-2] Entry on chloral. In: Römpp Online . Georg Thieme Verlag, accessed on May 18, 2016.

[CRC90_3_490-3] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-490.

[CRC90_5_21-4] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-21.

[Ullmann-5] R. Jira, E. Kopp, BC McKusick, G. Röderer, A. Bosch, G. Fleischmann: Chloroacetaldehydes. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag, Weinheim 2012, doi : 10.1002 / 14356007.a06_527.pub2 .

[6] DR Stull: Vapor Pressure of Pure Substances. Organic and Inorganic Compounds. In: Ind. Eng. Chem. 39, 1947, pp. 517-540, doi: 10.1021 / ie50448a022 .

[7] KB Wiberg, KM Morgan, H. Maltz: Thermochemistry of carbonyl reactions. 6. A study of hydration equilibria. In: J. Am. Chem. Soc. 116, 1994, pp. 11067-11077, doi: 10.1021 / ja00103a024 .