Bis (2-ethylhexyl) peroxydicarbonate
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| Simplified structural formula - mixture of three stereoisomers | ||||||||||||||||
| General | ||||||||||||||||
| Surname | Bis (2-ethylhexyl) peroxydicarbonate | |||||||||||||||
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| Molecular formula | C 18 H 34 O 6 | |||||||||||||||
| Brief description |
clear, colorless liquid |
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| properties | ||||||||||||||||
| Molar mass | 346.46 g mol −1 | |||||||||||||||
| Physical state |
liquid |
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| Melting point |
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| Vapor pressure |
<0.001 Pa (25 ° C) |
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| solubility |
almost insoluble in water, hydrolyzed to 2-ethylhexanol
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| Refractive index |
approx. 1.44 (15 ° C) |
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| 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 | ||||||||||||||||
Bis (2-ethylhexyl) peroxydicarbonate (also di- (2-ethylhexyl) peroxydicarbonate , DEHPC ) is a diester of the hypothetical peroxydicarbonic acid. The compounds with the general structure R-OC (O) OO- (O) CO-R with a branched 2-ethylhexyl (isooctyl) group as R are of technical importance and are usually present as a mixture of substances.
DEHPC is used as a radical initiator for polymerization - e.g. B. from vinyl chloride to PVC - and for the crosslinking of z. B. polypropylene is used.
Isomerism
DEHPC has a stereocenter at each branch point of the two 2-ethylhexyl residues, so there are three DEHPC stereoisomers :
- ( R , R ) -DEHPC,
- ( S , S ) -DEHPC and
- meso -DEHPC.
In technology, DEHPC is used almost exclusively as a mixture of these three stereoisomers. As a rule, such stereoisomers have different physiological and thus also toxicological properties.
Occurrence and representation
Peroxydicarbonates are thermally unstable percompounds and by acylation of hydrogen peroxide accessible Chlorameisensäureestern. In the reaction of a mixture of 2-ethylhexyl chloroformate ( easily accessible from 2-ethylhexanol and phosgene ) and dilute hydrogen peroxide solution in isopropanol with dilute sodium hydroxide solution at 15 ° C., bis (2-ethylhexyl) peroxydicarbonate is obtained in 99.3% yield.
The reaction was also carried out by the method of microreaction technology and gives similarly high yields.
properties
Bis (2-ethylhexyl) peroxydicarbonate is a clear, colorless liquid with a pungent odor that is insoluble in water and quickly hydrolyzes to 2-ethylhexanol.
DEHPC is found in many organic solvents, including a. also mineral oil - referred to in technical literature as OMS ( odourless mineral spirits ) - or phthalic acid esters soluble.
As a peroxo compound, DEHPC contains approx. 4.48 percent by weight of active oxygen and has a so-called self-accelerating decomposition temperature (SADT) of approx. 0 ° C or approx. 10 ° C. The SADT is the lowest temperature at which self-accelerating decomposition can occur in the transport packaging within a week and which must not be exceeded during storage and transport. DEHPC should therefore be stored below −15 ° C or −20 ° C. Dilution with high boiling solvents increases the SADT.
The half-life of DEHPC, at which 50% of the peroxydicarbonate is decomposed, is 10 hours at 47 ° C, one hour at 64 ° C and 0.1 hours at 83 ° C and is therefore considerably shorter than that of the perester tert - Butyl peroxybenzoate .
Amines, transition metal ions, strong acids and bases, strong reducing and oxidizing agents as well as rust and dust accelerate the decomposition of DEHPC even in low concentrations. The main decomposition products of DEHPC are carbon dioxide and 2-ethylhexanol.
Addition of unsaturated carbonyl compounds, such as. B. ethyl sorbate, furan-2-carboxylic acid methyl ester or ethyl cinnamate as stabilizers increase the SADT up to> 10 ° C.
Applications
Bis (2-ethylhexyl) peroxydicarbonate is used as a free-radical initiator, the polymerization of monomers to polymers , such as. B. from ethylene to LDPE , vinyl chloride (VCM) to polyvinyl chloride (PVC), vinylidene chloride to polyvinylidene chloride , styrene to polystyrene or acrylic acid esters to polyacrylates or methacrylic acid esters to polymethacrylates and their copolymers.
The polymerization of VCM to PVC can be carried out both as bulk polymerization and as suspension polymerization at temperatures of 45-60 ° C and initiator doses of 0.02-0.1%. For more uniform polymerization and complete monomer conversion, combinations of bis (2-ethylhexyl) peroxydicarbonate with thermally more stable peroxides, such as. B. dilauroyl peroxide used.
The crosslinking of polypropylene with DEHPC to achieve higher tensile strengths and melting temperatures is also described.
Bis (2-ethylhexyl) peroxydicarbonate is marketed as Trigonox EHPS ( AkzoNobel ), Luperox 223S ( Arkema ) and EHPC-S ( United Initiators ).
Individual evidence
- ↑ a b Entry on bis (2-ethylhexyl) peroxydicarbonate in the GESTIS substance database of the IFA , accessed on August 2, 2016(JavaScript required) .
- ↑ a b c d e f g akzonobel: Safety data sheet, Trigonox EHPS. AkzoNobel, accessed September 22, 2018 .
- ↑ a b c d e f g Arkema: GPS Safety Summary, Substance Name: Di-2-ethylhexyl peroxydicarbonate , accessed on December 27, 2019.
- ↑ a b c d e United-initiators: EHPC-S, Technical Data Sheet - Polymerization Peroxycarbonates , accessed on December 27, 2019.
- ↑ O. Nuyken, J. Crivello: poly (vinyl ether) s, poly (vinyl ester) s, and poly (vinyl halides) s Handbook of Polymer Synthesis, Part A . Ed .: HR Kricheldorf. Marcel Dekker, Inc., New York 1992, ISBN 0-8247-8514-2 , pp. 176 .
- ^ EJ Ariëns, Stereochemistry, a basis for sophisticated nonsense in pharmacokinetics and clinical pharmacology , European Journal of Clinical Pharmacology 26 (1984) 663-668, doi : 10.1007 / BF00541922 .
- ↑ Patent US4394328 : Production of peroxydicarbonates. Applied on March 27, 1980 , published July 19, 1983 , Applicant: PPG Industries, Inc., Inventor: JA Barter, DE Kellar.
- ↑ Patent EP1937630B1 : Process for the production of organic peroxides using microreaction technology. Registered on October 13, 2006 , published on August 3, 2011 , applicant: Ehrfeld Mikrotechnik BTS GmbH and Pergan auxiliary materials for industrial processes GmbH, inventor: A. Azzawi, H.-E. Mehesch, E. v. Zadow, S. Kirsch, M. Sondermann.
- ↑ The Society of the Plastics Industry, Organic Peroxide Producers Safety Division: SAFETY AND HANDLING OF ORGANIC PEROXIDES, 2012 edition ( Memento from April 1, 2016 in the Internet Archive )
- ↑ a b c Product Data Sheet, Trigonox EHPS. In: Product data sheet. AkzoNobel, September 2015, accessed August 2, 2016 .
- ↑ Patent US7214812B2 : Stabilized peroxydicarbonate preparation. Registered on June 26, 2002 , published on May 8, 2007 , applicant: Peroxid-Chemie GmbH & Co. KG, inventors: E. Hägel, M. Kunz, W. Zeiss.
- ↑ Patent DE1927761 : Process for the polymerization of olefinically unsaturated compounds. Registered on May 30, 1969 , published on December 10, 1970 , applicant: Elektrochemische Werke München AG, inventors: H. Winter, H. Meyer, W. Edl, W. Meister, H. Schwarzer.
- ↑ Patent US5416169 : Polypropylene having a high melt-tensile strength, a process for producing the same and a molded product from the same. Applied on November 5, 1993 , published on May 16, 1995 , Applicant: Chisso Corp., Inventor: J. Saito, S. Kawazoe, S. Kikukawa.