Propylene oxide

Structural formula
	Simplified structural formula without stereochemistry
General
Surname	Propylene oxide
other names	2-methyloxirane ( IUPAC ); 1,2-epoxy propane; Methyl oxirane; Propylene oxide;
Molecular formula	C 3 H 6 O
Brief description	colorless liquid with an ethereal odor
External identifiers / databases
EC number	200-879-2
ECHA InfoCard	100,000,800
PubChem	6378
ChemSpider	6138
Wikidata	Q727742
properties
Molar mass	58.08 g mol −1
Physical state	liquid
density	0.83 g cm −3 (20 ° C)
Melting point	−112 ° C
boiling point	34 ° C
Vapor pressure	588 h Pa (20 ° C); 868 hPa (30 ° C); 1240 hPa (40 ° C); 1740 hPa (50 ° C);
solubility	good in water (681 g l −1 at 20 ° C)
safety instructions
H and P phrases	H: 224-311 + 331-302-315-319-335-340-350
	P: 201-210-261-280-305 + 351 + 338-308 + 313
Authorization procedure under REACH	particularly worrying : carcinogenic, mutagenic ( CMR )
MAK	DFG : 2 ml m −3 , 4.8 mg m −3 ; Switzerland: 2.5 ml m −3 or 6 mg m −3 ;
Toxicological data	380 mg kg −1 ( LD 50 , rat , oral )
Thermodynamic properties
ΔH f 0	−123.0 kJ / mol (l) ; −94.7 kJ / mol (g)
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Propylene oxide or 1,2-epoxypropane (PO) is a heterocyclic organic compound from the group of epoxides (oxiranes) . The easily flammable, colorless liquid, soluble in water and alcohol, has an ethereal odor. Propylene oxide is obtained from propene and is mainly used for the production of water-soluble propylene glycol derivatives, but can also be used as a corrosion protection additive for pesticides , cooling liquids and disinfectants . The epoxide propylene oxide is not a naturally occurring substance; its occurrence in the atmosphere is attributed to industrial emissions and their further processing.

Presentation and extraction

In 1985 the production of propylene oxide was around 2.9 Mt worldwide , in 1991 around 4.2 Mt, in 2001 around 4.8 Mt and in 2008 around 5.5 Mt. The installed worldwide annual production capacity on January 1, 2002 was around 5.8 Mt.

A direct oxidation of propene with oxygen to propylene oxide, as in the production of ethylene oxide from ethene, is technically possible, but uneconomical because the reaction proceeds with a low selectivity and with the formation of several oxidation products that would have to be separated in a laborious manner. Typical by-products are acetaldehyde, formaldehyde and carbon monoxide and their oxidation products. In this respect, the methods described below have prevailed.

Chlorohydrin process

In the chlorohydrin process, an isomer mixture of 1-chloro-2-propanol and 2-chloro-1-propanol is produced from propene with chlorine and water (with hypochlorous acid being generated in situ ) . In a second reaction step, these are reacted with hydroxide ions to form propylene oxide and water. The hydroxide ions are obtained from milk of lime Ca (OH) ₂ , so that calcium chloride CaCl ₂ is obtained as a by- product (200 kg calcium chloride per 100 kg propylene oxide). This leads to a large waste water pollution.

The proportion of propylene oxide production capacity based on the chlorohydrin process was around 55% worldwide in 1985, around 52% in 1991 and only around 34% in 2010.

Oxirane process (Prileschajew reaction)

The epoxidation of propene is carried out at the Prileschajew reaction on the catalytic reaction with a hydroperoxide , which strongly reactive peroxide group with the double bond of the propene reacts.

In the styrene variant , ethylbenzene is converted with oxygen into the corresponding peroxide, which reacts with propene to form propylene oxide. The 1-phenylethanol (phenylmethylcarbinol) formed in parallel is reacted with aluminum oxide to form styrene with elimination of water.

{\ displaystyle \ mathrm {C_ {3} H_ {6} \ + \ C_ {8} H_ {10} O_ {2} {\ xrightarrow {Cat.}} C_ {3} H_ {6} O \ + \ C_ {8} H_ {10} O {\ xrightarrow {Al2O3}} C_ {3} H_ {6} O \ + \ C_ {8} H_ {8} \ + \ H_ {2} O}}

In this process, approx. 1.8 tons of styrene are produced as a by-product per ton of propylene oxide produced.

In the iso-butane variant , iso-butane is converted into tert-butyl hydroperoxide by oxidation , which reacts with propylene to form propylene oxide and tert-butanol . The tert-butanol can then be returned to isobutene by dehydration and this can be returned to isobutane with hydrogen.

HPPO process

In this process, similar to the Prileschajew reaction, the propylene is converted with hydrogen peroxide ( HP ):

{\ displaystyle \ mathrm {C_ {3} H_ {6} \ + \ H_ {2} O_ {2} \ longrightarrow \ C_ {3} H_ {6} O \ + \ H_ {2} O}}

Since water is the only secondary product , this process is particularly economical and environmentally friendly. It requires an upstream plant for the production of hydrogen peroxide, but in contrast to the other processes does not have to have any infrastructure or markets for by-products. In 2008, the Korean SKC commissioned the world's first large-scale plant for the production of propylene oxide using the Evonik / Uhde HPPO process in Ulsan ( South Korea ) . The plant has an annual capacity of 100,000 tons. Another, much larger plant that uses a similar process was built in Antwerp in 2008 and is operated jointly by BASF and Dow Chemical . Dow Chemical is commissioning another large-scale plant in Jubail in 2016 .

Enantiomerically pure propylene oxide

The synthesis of the propylene oxide enantiomers starts from ( R ) - or ( S ) - alanine . This is initially converted into 2-chloropropionic acid with retention with sodium nitrite and hydrochloric acid . After reduction with lithium aluminum hydride to alcohol and ring closure with sodium hydroxide with inversion , the ( S ) - or ( R ) -propylene oxide are obtained.

properties

Physical Properties

According to Antoine, the vapor pressure function results from log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 4.09487, B = 1065.27 and C = −46 , 86 in the temperature range from 199.7 to 307.4 K.

Compilation of the most important thermodynamic properties
property	Type	Value [unit]	Remarks
Standard enthalpy of formation	Δ _f H ⁰_liquid Δ _f H ⁰_gas	−122.6 kJ mol ⁻¹ −94.68 kJ mol ⁻¹	as a liquid as a gas
Enthalpy of combustion	Δ _c H ⁰_liquid	−1917.4 kJ mol ⁻¹
Heat capacity	c _p	125.1 J mol ⁻¹ K ⁻¹ (25 ° C) 75.55 J mol ⁻¹ K ⁻¹ (25 ° C)	as a liquid as a gas
Critical temperature	T _c	482.3 K
Critical pressure	p _c	49.23 bar
Critical volume	ρ _c	0.186 l mol ⁻¹
Enthalpy of fusion	Δ _f H ⁰	6.569 kJ mol ⁻¹	at the melting point
Enthalpy of evaporation	Δ _V H ⁰	30.1 kJ mol ⁻¹	at normal pressure boiling point

Chemical properties

Propylene oxide has less tendency to self- polymerize than ethylene oxide , but this can be initiated with acid catalysis by catalysts such as the salts aluminum , iron or tin chloride , as well as all acids and alkali metals , and can be explosive. The heat of polymerization is −76 kJ · mol ⁻¹ or –1310 kJ · kg ⁻¹ . With water, slow hydrolysis occurs in the cold, and rapid hydrolysis at high temperatures of 200–220 ° C to form 1,2-propanediol (propylene glycol).

Safety-related parameters

Propylene oxide forms highly flammable vapor-air mixtures. The compound has a flash point of −38 ° C. The explosion range is between 1.9% by volume (45 g / m³) as the lower explosion limit (LEL) and 38.8% by volume (938 g / m³) as the upper explosion limit (UEL). A correlation of the explosion limits with the vapor pressure function results in a lower explosion point of −44 ° C. The maximum explosion pressure is 9.1 bar. The limit gap width was determined to be 0.7 mm (50 ° C). This results in an assignment to explosion group IIB. With a minimum ignition energy of 0.13 mJ, vapor-air mixtures are extremely ignitable. The ignition temperature is 430 ° C. The substance therefore falls into temperature class T2.

toxicity

Propylene oxide has been shown to be carcinogenic (carcinogenic) and mutagenic (mutagenic) in animal experiments. The substance, which is also acutely harmful to health, irritates the skin, eyes and respiratory tract; its vapors have a narcotic effect; Harmful contamination of the air can occur at temperatures as low as 20 ° C. It can be absorbed orally , pulmonarily or percutaneously , i.e. through the skin. Continuous or repeated exposure can cause sensitization. As a marine pollutant, the substance is classified in water hazard class 3.

Animal experiments show that inhaling propylene oxide up to a concentration of 150 ppm has no detectable effect. Repeated contact of the animals with the substance resulted in depression of the CNS and irritation of the eyes and respiratory tract. Since the odor threshold in the air is between 100 and 350 ppm, but the maximum permissible workplace concentration is only 2.5 ppm, the characteristic odor of the substance is not a sufficient indicator for propylene oxide.

additional

Propylene oxide is the first chiral molecule to be detected outside of the solar system.

literature

Wolfgang Swodenk, Helmut Waldmann: Modern processes in large-scale chemistry: ethylene oxide and propylene oxide. In: Chemistry in Our Time . 12th year No. 3, 1978, pp. 65-70. ISSN 0009-2851

Web links

Guidelines for the distribution of propylene oxide, www.petrochemistry.net (PDF file; 1.1 MB)

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u Entry on propylene oxide in the GESTIS substance database of the IFA , accessed on May 4, 2020(JavaScript required) .
↑ Entry on Methyloxirane in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Entry in the SVHC list of the European Chemicals Agency , accessed on July 17, 2014.
↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 75-56-9 or 1,2-epoxypropane ), accessed on September 15, 2019.
↑ CRC-Handbook 90th edition (2009–2010), pp. 5–24 ( Memento of April 26, 2015 in the Internet Archive ). - see also entry on propylene oxide . In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD, accessed on 22 March 2010 .
↑ CEH report Propylene Oxide
↑ Karl Hans Simmrock: The manufacturing process for propylene oxide and its electrochemical alternative. In: Chemical Engineer Technology. 48, 1976, pp. 1085-1096. doi: 10.1002 / cite.330481203 .
↑ The world's first HPPO system under license from Evonik and Uhde at SKC, Korea, successfully commissioned. on chemie.de , July 29, 2008.
↑ BASF, Dow and Solvay use new innovative HPPO technology in Antwerp (PDF; 23 kB).
↑ V. Schurig, B. Koppenhofer, W. Bürkle: Correlation of the absolute configuration of chiral epoxides by complexation chromatography; Synthesis and enantiomeric purity of (+) - (R) - and (-) - (S) -1,2-epoxypropane. In: Angew. Chem. 90, 1978, pp. 993-995.
↑ ^a ^b R.A. McDonald, SA Shrader, DR Stull: Vapor Pressures and Freezing Points of Thirty Pure Organic Compounds. In: J. Chem. Eng. Data . 4, 1959, pp. 311-313, doi: 10.1021 / je60004a009 .
↑ ^a ^b ^c G. C. Sinke, DL Hildenbrand: Heat of formation of propylene oxide. In: J. Chem. Eng. Data. 7, 1962, p. 74.
↑ ^a ^b R. H. Beaumont, B. Clegg, G. Gee, JBM Herbert, DJ Marks, RC Roberts, D. Sims: Heat capacities of propylene oxide and of some polymers of ethylene and propylene oxides. In: polymer. 7, 1966, pp. 401-416.
^ J. Chao: Thermodynamic properties of key organic oxygen compounds in the carbon range C1 to C4. Part 2. Ideal gas properties. In: J. Phys. Chem. Ref. Data . 15, 1986, pp. 1369-1436, doi: 10.1063 / 1.555769 .
↑ ^a ^b ^c K. A. Kobe, AE Ravicz, SP Vohra: Critical Properties and Vapor Pressures of Some Ethers and Heterocyclic Compounds. In: J. Chem. Eng. Data. 1, 1956, 50.
↑ Employer's liability insurance association for raw materials and chemical industry , leaflet R 008 Polyreactions and polymerizable systems. Edition 05/2015, ISBN 978-3-86825-069-5 .
↑ ^a ^b ^c ^d E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.
↑ Brett A. McGuire, P. Brandon Carroll, Ryan A. Loomis, Ian A. Finneran, Philip R. Jewell: Discovery of the interstellar chiral molecule propylene oxide (CH3CHCH2O) . In: Science . June 14, 2016, ISSN 0036-8075 , p. aae0328 , doi : 10.1126 / science.aae0328 , PMID 27303055 ( sciencemag.org [accessed June 15, 2016]).
↑ Thorsten Dambeck: Milky Way: Researchers discover first mirror molecule in space. In: Spiegel online. Retrieved June 15, 2016 .
↑ Harald Frater: scinexx | First chiral molecule discovered in space: Propylene oxide occurs in two variants in the galactic molecular cloud. In: www.scinexx.de. Retrieved June 17, 2016 .

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u Entry on propylene oxide in the GESTIS substance database of the IFA , accessed on May 4, 2020(JavaScript required) .

[CLP_100.000.800-2] Entry on Methyloxirane in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[SVHC-3] Entry in the SVHC list of the European Chemicals Agency , accessed on July 17, 2014.

[4] Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 75-56-9 or 1,2-epoxypropane ), accessed on September 15, 2019.

[5] CRC-Handbook 90th edition (2009–2010), pp. 5–24 ( Memento of April 26, 2015 in the Internet Archive ). - see also entry on propylene oxide . In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD, accessed on 22 March 2010 .

[CEH_report_Propylene_Oxide-6] CEH report Propylene Oxide

[7] Karl Hans Simmrock: The manufacturing process for propylene oxide and its electrochemical alternative. In: Chemical Engineer Technology. 48, 1976, pp. 1085-1096. doi: 10.1002 / cite.330481203 .

[8] The world's first HPPO system under license from Evonik and Uhde at SKC, Korea, successfully commissioned. on chemie.de , July 29, 2008.

[9] BASF, Dow and Solvay use new innovative HPPO technology in Antwerp (PDF; 23 kB).

[10] V. Schurig, B. Koppenhofer, W. Bürkle: Correlation of the absolute configuration of chiral epoxides by complexation chromatography; Synthesis and enantiomeric purity of (+) - (R) - and (-) - (S) -1,2-epoxypropane. In: Angew. Chem. 90, 1978, pp. 993-995.

[McDonald-11] R.A. McDonald, SA Shrader, DR Stull: Vapor Pressures and Freezing Points of Thirty Pure Organic Compounds. In: J. Chem. Eng. Data . 4, 1959, pp. 311-313, doi: 10.1021 / je60004a009 .

[Sinke-12] G. C. Sinke, DL Hildenbrand: Heat of formation of propylene oxide. In: J. Chem. Eng. Data. 7, 1962, p. 74.

[Beaumont-13] R. H. Beaumont, B. Clegg, G. Gee, JBM Herbert, DJ Marks, RC Roberts, D. Sims: Heat capacities of propylene oxide and of some polymers of ethylene and propylene oxides. In: polymer. 7, 1966, pp. 401-416.

[Chao-14] J. Chao: Thermodynamic properties of key organic oxygen compounds in the carbon range C1 to C4. Part 2. Ideal gas properties. In: J. Phys. Chem. Ref. Data . 15, 1986, pp. 1369-1436, doi: 10.1063 / 1.555769 .

[Kobe-15] K. A. Kobe, AE Ravicz, SP Vohra: Critical Properties and Vapor Pressures of Some Ethers and Heterocyclic Compounds. In: J. Chem. Eng. Data. 1, 1956, 50.

[16] Employer's liability insurance association for raw materials and chemical industry , leaflet R 008 Polyreactions and polymerizable systems. Edition 05/2015, ISBN 978-3-86825-069-5 .

[Brandes-17] E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.

[18] Brett A. McGuire, P. Brandon Carroll, Ryan A. Loomis, Ian A. Finneran, Philip R. Jewell: Discovery of the interstellar chiral molecule propylene oxide (CH3CHCH2O) . In: Science . June 14, 2016, ISSN 0036-8075 , p. aae0328 , doi : 10.1126 / science.aae0328 , PMID 27303055 ( sciencemag.org [accessed June 15, 2016]).

[19] Thorsten Dambeck: Milky Way: Researchers discover first mirror molecule in space. In: Spiegel online. Retrieved June 15, 2016 .

[20] Harald Frater: scinexx | First chiral molecule discovered in space: Propylene oxide occurs in two variants in the galactic molecular cloud. In: www.scinexx.de. Retrieved June 17, 2016 .