1,2-butanediol

Structural formula
Simplified structural formula without stereochemistry
General
Surname	1,2-butanediol
other names	Butane-1,2-diol ( IUPAC ) 1,2-butylene glycol 1,2-BUTANEDIOL ( INCI )
Molecular formula	C 4 H 10 O 2
Brief description	colorless, viscous liquid
External identifiers / databases
CAS number 584-03-2 [racemate] 40348-66-1 [ (R) -enantiomer] 73522-17-5 [ (S) -enantiomer] EC number 209-527-2 ECHA InfoCard 100.008.663 PubChem 11429 ChemSpider 10948 Wikidata Q161457
properties
Molar mass	90.12 g mol −1
Physical state	liquid
density	1.01 g cm −3 (20 ° C)
Melting point	−114 ° C
boiling point	192 ° C
Vapor pressure	0.1 h Pa (20 ° C)
solubility	miscible with water easily soluble in alcohol
Refractive index	1.438 (20 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary Caution H and P phrases H: 319 P: 280-264-305 + 351 + 338-337-311
Toxicological data	16000 mg kg −1 ( LD 50 ,  rat ,  oral )
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

1,2-Butanediol (according to IUPAC nomenclature : butane-1,2-diol , sometimes also referred to as 1,2-butylene glycol ) is an organochemical compound from the group of dihydric alcohols , or more precisely saturated diols . It is mostly used as a solvent or intermediate in organic syntheses .

Isomers

1,2-Butanediol has one center of chirality ; there are two enantiomers: ( R ) -1,2-butanediol and ( S ) -1,2-butanediol. Without a further specifying addition, a mixture of the two substances is usually meant.

Isomers of 1,2-butanediol
Surname	( R ) -1,2-butanediol	( S ) -1,2-butanediol
Structural formula
CAS number	40348-66-1	73522-17-5
	584-03-2 (unspec.)
EC number	805-781-9	805-782-4
	209-527-2 (unspec.)
ECHA info card	100.232.775	100.232.776
	100.008.663 (unspec.)
PubChem	641012	6993189
	11429 (unspec.)
Wikidata	Q27123549	Q27123550
	Q161457 (unspec.)

Extraction and presentation

1,2-butanediol is technically hydration of 1,2-epoxybutane prepared bar without a catalyst at temperatures of 160-220 ° C and pressures of from 10-30.

A 10 to 20-fold molar excess of water is used in order to reduce the formation of polyethers . The selectivities to 1,2-butanediol are 72–92%, depending on the excess water.

The reaction can also be carried out in the presence of a strongly acidic ion exchange resin or smaller amounts of sulfuric acid at temperatures below 160 ° C. and at a slight excess pressure.

It can also be obtained by OsO ₄ oxidation of 1- butene in the course of a dihydroxylation .

properties

Physical Properties

Butane-1,2-diol has a relative gas density of 3.1 (density ratio to dry air at the same temperature and pressure ) and a relative density of the steam-air mixture of 1.00 (density ratio to dry air at 20 ° C and normal pressure ). In addition, 1,2-butanediol has a vapor pressure of 0.1 hPa at 20 ° C. The dynamic viscosity is 73 mPa · s at 20 ° C.

Chemical properties

1,2-Butanediol is a flammable, hardly inflammable liquid from the group of alcohols . The substance is miscible with water in all proportions, easily soluble in alcohols and sparingly soluble in esters and ethers . 1,2-Butanediol is insoluble in hydrocarbons . Furthermore, it is considered difficult or very difficult to volatilize. The substance decomposes into formaldehyde when exposed to heat . 1,2-Butanediol can react dangerously with oxidizing agents , reducing agents , acids , acid anhydrides , acid chlorides and chloroformates.

use

1,2-Butanediol is used as a solvent and humectant as well as for the production of epoxy resins , polyamides and polyurethanes . The esters and ethers of 1,2-butanediol are also used as plasticizers .

safety instructions

1,2-Butanediol is a flammable, but hardly inflammable substance. The substance is mainly absorbed through the respiratory tract . Furthermore, a very effective absorption through the skin and the digestive tract is suspected. Acute eye irritation occurs upon ingestion or exposure . Chronic information is not available for humans. A reproductive toxicity and a mutagenic effect could be excluded by tests. Insufficient information is available on carcinogenicity . The ignition temperature is 390 ° C. The substance therefore falls into temperature class T2 and explosion group IIA. The lower explosion point is 92 ° C. With a flash point of 102 ° C, 1,2-butanediol is considered flame-retardant.

Web links

Commons : 1,2-Butanediol  - Collection of Pictures, Videos, and Audio Files

Individual evidence

1. ↑ Entry on 1,2-BUTANDIOL in the CosIng database of the EU Commission, accessed on February 25, 2020.
2. ↑ ^{a b c d e f g h i j k l} Entry on 1,2-butanediol in the GESTIS substance database of the IFA , accessed on August 7, 2019(JavaScript required) .
3. ↑ ^{a b} Entry on butanediols. In: Römpp Online . Georg Thieme Verlag, accessed on August 7, 2019.
4. ↑ Data sheet 1,2-butanediol from Sigma-Aldrich , accessed on August 7, 2019 ( PDF ).
5. ↑ Entry on butane-1,2-diol in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 7, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .
6. ↑ ^{a b c d} Heinz Gräfje, Wolfgang Körnig, Hans ‐ Martin Weitz, Wolfgang Reiss, Guido Steffan, Herbert Diehl, Horst Bosche, Kurt Schneider, Heinz Kieczka, Rolf Pinkos: Butanediols, Butenediol, and Butynediol. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley ‐ VCH Verlag GmbH & Co. KGaA., July 23, 2019, p. 11, doi : 10.1002 / 14356007.a04_455.pub2 (section “1,2-Butanediol”).