3-chloro-1,2-propanediol

Structural formula
Representation without specifying the stereoisomerism
General
Surname	3-chloro-1,2-propanediol
other names	( RS ) -3-chloro-1,2-propanediol 3-MCPD ( R ) -3-chloro-1,2-propanediol ( S ) -3-chloro-1,2-propanediol (±) -3-chloro-1,2-propanediol rac -3-chloro-1,2-propanediol 3-monochloropropane-1,2-diol Chloropropylene glycol Glycerol monochloride Glycerol-α-monochlorohydrin α-chlorohydrin
Molecular formula	C 3 H 7 ClO 2
Brief description	colorless, hygroscopic, almost odorless liquid
External identifiers / databases
CAS number 96-24-2 [( RS ) - (±) -3-chloro- 1,2-propanediol] 57090-45-6 [( R ) - (-) - 3-chloro-1,2- propanediol] 60827-45-4 [( S ) - (+) - 3-chloro-1,2- propanediol] PubChem 7290 Wikidata Q223066
properties
Molar mass	110.54 g mol −1
Physical state	liquid
density	1.32 g cm −3
Melting point	−40 ° C
boiling point	213 ° C (decomposition)
Vapor pressure	1 Pa (20 ° C)
solubility	miscible with water
Refractive index	1.4809 (20 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 290-300-312-330-315-318-319-360F-372 P: 201-260-280-302 + 352-304 + 340-305 + 351 + 338-308 + 310
MAK	Switzerland: 0.005 ml m −3 or 0.023 mg m −3
Toxicological data	26 mg kg −1 ( LD 50 ,  rat ,  oral )
Thermodynamic properties
ΔH f 0	−525.3 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

The substance 3-chloro-1,2-propanediol , abbreviated as 3-MCPD (3- M ono c hlor p ropan d iol), a chemical compound from the group of chlorinated diols . 3-MCPD can be viewed as a monochlorine derivative of glycerol .

If "3-chloro-1,2-propanediol" or "3-MCPD" is mentioned in this text or in the scientific literature without any additional name ( prefix ), ( RS ) -3-chloro-1,2-propanediol ( Synonym: DL -3-chloro-1,2-propanediol) meant, i.e. the racemate .

Occurrence and extraction

Similar to acrylamide and the long-known acrolein , 3-chloro-1,2-propanediol has been observed as a toxic substance during the production process of high-fat and salty foods when heated. So far, it has been analytically proven in bread , seasoned sauces ( soy sauce ), smoked meat products , fats and oils as well as in baby milk powder. 3-MCPD can also arise from the alliin found in onions .

3-chloro-1,2-propanediol occurs both in free and in esterified form - especially in the case of fats and oils - with fatty acids as 3-MCPD fatty acid esters .

It can also be made from glycerine and hydrogen chloride :

${\displaystyle \mathrm {C_{3}H_{8}O_{3}+HCl\longrightarrow C_{3}H_{7}O_{2}Cl+H_{2}O} }$

Emergence

The chemical formation process is probably a partial or complete saponification of the fats with the chloride ion (from the salt) as the nucleophile .

properties

Stereoisomerism

3-chloro-1,2-propanediol is chiral , it contains a stereocenter in the 2-position. There are thus two stereoisomers: ( R ) - (-) - 3-chloro-1,2-propanediol and the enantiomeric ( S ) - (+) - 3-chloro-1,2-propanediol.

( R ) -3-chloro-1,2-propanediol

( S ) -3-chloro-1,2-propanediol

Analytics

For a reliable qualitative and quantitative determination can, after an appropriate sample preparation , the gas chromatography-mass spectrometry can be used.

Toxicity when ingested

The Federal Institute for Risk Assessment (BfR) assumes that the 3-MCPD fatty acid esters are converted into free 3-chloro-1,2-propanediol during digestion:

The European Food Safety Authority (EFSA) has confirmed this assessment. According to an initial toxicological assessment, the BfR does not speak of an acute danger for adults, infants and small children. The tolerable daily intake of 2 µg per kg of body weight per day can, however, be exceeded 3 to 20 times. The consumer magazine Öko-Test even criticized some breast milk substitute products that the limit value recommended by the BfR was exceeded by up to 35 times. The BfR therefore sees “a need for action with regard to minimizing the levels”.

For free 3-chloro-1,2-propanediol could in vivo , ie, in animal experiments , a carcinogenicity be detected.

The Scientific Food Committee considers the daily consumption of 0.002 mg / kg 3-MCPD or 3-MCPD esters to be harmless.

use

3-Chloro-1,2-propanediol is used as an intermediate in the manufacture of dyes and pharmaceuticals.

See also

• 2-chloro-1,3-propanediol (structural isomer, symmetrical and non-chiral)
• 1,3-dichloro-2-propanol (1,3-DCP): Also occurs as an impurity in food together with 3-MCPD.

Web links

• Federal Institute for Risk Assessment : Statement on 3-MCPD fatty acid esters in food , as of: 2012
• Federal Institute for Risk Assessment : Selected questions and answers on 3-monochloropropanediol (3-MCPD) , status: 2007

Individual evidence

1. ↑ ^{a b c d e f g h i} Entry on 3-chloro-1,2-propanediol in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .
2. ↑ 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. 3-112.
3. ↑ Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 3-chloro-1,2-propanediol ), accessed on November 25, 2019.
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. 5-24.
5. ↑ 3-MCPD in food . food.org. Retrieved November 1, 2009.
6. ↑ Page no longer available , search in web archives: Message from the information service of the Baden-Württemberg Agriculture Administration .
7. ↑ Kuhlmann J: 2-Monochloropropanediol (2-MCPD), 3-Monochloropropanediol (3-MCPD), and Glycidol in Infant and Adult / Pediatric Nutritional Formula: Single-Laboratory Validation, First Action 2018.12. , J AOAC Int. 2019 Jul 1; 102 (4): 1205-1220, PMID 30992094
8. ↑ ^{a b} Statement of the Scientific Panel on Contaminants in the Food chain (CONTAM) on a request from the European Commission related to 3-MCPD esters . In: EFSA Journal . tape 6 , no. 3 , 2008, p. 1048 , doi : 10.2903 / j.efsa.2008.1048 .
9. ↑ Food monitoring BaWü: 3-MCPD esters in refined edible fats and oils - updated report .
10. ↑ Page no longer available , search in web archives: test of breast milk substitute products by the consumer magazine Öko-Test  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
11. ↑ Questions and answers on the contamination of food with 3-MCPD, 2-MCPD and glycidyl fatty acid esters. In: bund.de. BfR , July 7, 2016, accessed on June 5, 2018 . 
12. ↑ Minister Willi Stächele MdL: "Examination results require further action" ( Memento from September 5, 2012 in the web archive archive.today ). MLR , May 12, 2003.
13. ↑ Infant formula and follow-on formula can contain 3-MCPD fatty acid esters which are harmful to health (PDF; 188 kB). BfR opinion No. 047/2007 of December 11, 2007.
14. ↑ Food standards: CHLOROPROPANOLS IN FOOD ( Memento from June 14, 2009 in the Internet Archive ) (PDF; 1.8 MB).