Ethylhexyl glycerine
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| Simplified structural formula without stereochemistry | |||||||||||||||||||
| General | |||||||||||||||||||
| Surname | Ethylhexyl glycerine | ||||||||||||||||||
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| Molecular formula | C 11 H 24 O 3 | ||||||||||||||||||
| Brief description |
clear colorless to almost colorless liquid |
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| properties | |||||||||||||||||||
| Molar mass | 204.31 g mol −1 | ||||||||||||||||||
| Physical state |
liquid |
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| density |
0.950-0.960 g · cm −3 at 20 ° C |
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| Melting point |
<-76 ° C |
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| boiling point | |||||||||||||||||||
| Vapor pressure |
approx. 0.003 hPa at 20 ° C |
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| solubility |
Slightly soluble in water (approx. 1 g · l −1 at 20 ° C), in alcohols , glycols and glycol ethers |
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| Refractive index |
1.449-1.453 (20 ° C, 589 nm) |
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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 | |||||||||||||||||||
Ethylhexylglycerin is an alkyl ether of glycerin which has a 2-ethylhexyl group in the 3-position and, as a vicinal diol, has a primary and a secondary hydroxyl group . The branched alkyl glycerol Octoxyglycerin is a nonionic surfactant , which is used as an emulsifier , dispersant and lubricant , but mainly in personal care products and deodorants.
Occurrence and representation
While ether lipids are by no means uncommon in nature, such as B. in shark liver oil, ethylhexylglycerin is a synthetic compound.
In order to obtain a monoalkylation product of the 1,2,3-triol glycerol that is as uniform as possible, several synthesis variants have been described, some of which are protected from glycerol, such as. B. Isopropylideneglycerin ran out, but are not very suitable for industrial standards.
Large-scale production processes start from epichlorohydrin , which is prepared with 2-ethylhexanol in the presence of sodium hydroxide and a phase transfer catalyst , such as. B. Tetrabutylammonium bromide is converted to 2-Ethyhexylglycidylether (90% yield) with the exclusion of water and solvents.
The opening of the oxirane ring in 2-ethylhexylglycidyl ether can take place under both alkaline and acidic conditions and requires long reaction times with low space-time yields in aqueous media. High-boiling by-products are also formed, which reduce the product yield.
In a continuous process, the ring opening is carried out with weakly acidic water at 275 ° C. under pressure (8 MPa) with very high yield (99%) and high selectivity (> 97%). After cleaning by reverse osmosis, the water is partially recycled to remove metal ions from the tube bundle reactor , which lead to discoloration of the product.
One patent claims the practically quantitative hydrolysis of the glycidyl ether in a water / DMSO mixture with the Lewis acid boron trifluoride BF 3 as a catalyst to form the 1,2-diol ethylhexylglycerol. Complete separation of the chloride from the reaction mixture is only possible by multiple extraction and distillation.
Alternatively, glycidol can be used as the starting material, which reacts with 2-ethylhexanol in the presence of alkali metal hydroxides to form 3- (2-ethylhexyloxy) propane-1,2-diol.
The yield of 36% with 100% conversion of glycidol achieved under optimal conditions with potassium hydroxide as a catalyst is unsatisfactory, however.
Isomerism
All of the manufacturing processes mentioned provide ethylhexylglycerin as a complex mixture of isomers .
properties
Ethylhexylglycerin is a clear, colorless, odorless, viscous (144 m Pa · s ) liquid that dissolves in organic solvents and is compatible with many common cosmetic ingredients. The substance is well tolerated by the skin, but irritating to the eyes in concentrations above 5%.
Because of its skin-softening effect, ethylhexylglycerin is added to a large number of liquid and semi-solid (e.g. creams and ointments) skin care preparations as emollients . In deodorants , it inhibits microbial growth and thus the formation of odors when sweating. The compound also acts as a fixative of perfume . Dermatics often contain ethylhexylglycerin as an enhancer for preservatives , such as. B. phenoxyethanol and methylisothiazolinone , in concentrations of 0.3 to 1%.
Risk assessment
In the literature there are several references to an allergic effect of ethylhexylglycerin, e.g. B. in sun creams, in a skin ointment and a skin spray based on individuals and in different EHG-containing preparations (13 people in the period 1990 to 2015)
In view of the different properties and therefore diverse applications for ethylhexylglycerin in personal care and cosmetics over a long period of time, there are only relatively few documented cases of contact dermatitis due to ethylhexylglycerin . The 2011 Cosmetic Ingredient Review states: " CONCLUSION : The CIR Expert Panel concluded that the following cosmetic ingredients are safe in the present practices of use and concentration described in this safety assessment: • Ethylhexylglycerin"
Manufacturer and trade name
- Schülke & Mayr , sensiva® SC 50 (contains ethylhexylglycerine with α- tocopherol as a stabilizer)
- Kaō , Penetol® GE-EH
- Thor Group Ltd. , Microcare® Emollient EHG
- Inolex, Lexgard® E.
literature
- Marc Sutter: Nouvelles méthodes d'accès aux éthers de glycérol . Ed .: Université Claude Bernard Lyon I. Lyon 2013 ( archives-ouvertes.fr ).
- Marc Sutter, Eric Da Silva, Nicolas Duguet, Yann Raoul, Estelle Métay, Marc Lemaire: Glycerol Ether Synthesis . In: Chem. Rev. Band 115 , no. 16 , 2015, p. 8609-8651 , doi : 10.1021 / cr5004002 .
Web links
Schülke: http://www.ethylhexylglycerin.com/ethylhexylglycerin/
Individual evidence
- ↑ Entry on ETHYLHEXYLGLYCERIN in the CosIng database of the EU Commission, accessed on March 20, 2020.
- ↑ Entry on 3- (2-Ethylhexyloxy) propane-1,2-diol in the GESTIS substance database of the IFA , accessed on March 19, 2020 (JavaScript required)
- ↑ a b c d e f g h i j k Safety Data Sheet, sensiva® SC 50. In: schülke. Schülke & Mayr GmbH, January 17, 2017, accessed on March 19, 2020 .
- ↑ a b c d Final Safety Assessment: On the Safety Assessment of Alkyl Glyceryl Ethers As Used in Cosmetics. Cosmetic Ingredient Review, December 19, 2011, accessed March 19, 2020 .
- ↑ CG Bordier, N. Sellier, AP Foucault, F. Le Goffic: Purification and characterization of deep sea shark Centrophorus squamosus liver oil 1-O-alkylglycerol ether lipids . In: Lipids . tape 31 , no. 5 , 2014, p. 521-528 , doi : 10.1007 / bf02522646 .
- ↑ Patent US6392064B2 : Method of synthesizing glycidyl ether compounds in the absence of water and organic solvents. Applied on March 29, 2001 , published on May 21, 2002 , Applicant: Korea Research Institute of Chemical Technology, Inventor: BM Lee, H.-C. Kang, J.-M. Park, JH Yoon.
- ↑ Patent EP2277849A1 : Process for the preparation of 1-alkyl glycerol ethers. Registered on June 9, 2010 , published on January 26, 2011 , applicant: L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude and Schülke & Mayr GmbH, inventors: W. Beilfuss, R. Gradke , K. Weber, M. Balthasar, H.-G. Steffen.
- ↑ Patent EP1880988B1 : Process for producing glyceryl ether. Filed March 31, 2006 , published December 21, 2011 , applicant: Kao Corp., inventor: A. Saito, K. Naka, T. Shirasawa.
- ↑ A. Saito, T. Shirasawa, S. Tanahashi, M. Uno, N. Tatsumi, T. Kitsuki: An efficient synthesis of glyceryl ethers: catalyst-free hydrolysis of glycidyl ethers in water media . In: Green Chem. Band 11 , no. 6 , 2009, p. 753-755 , doi : 10.1039 / B821881A .
- ↑ Patent KR101528751B1 : Method for producing ethylhexylglycerin. Filed November 5, 2014 , published June 16, 2015 , Applicants: Yeo Myung Biochem Co., Ltd., Inventors: HJ An, JD Lee, HY Lee, DH Park.
- ↑ A. Leal-Duaso, M. Caballero, A. Urriolabeitia, JA Mayoral, JI García, E. Pires: Synthesis of 3-alkoxypropan-1,2-diols from glycidol: experimental and theoretical studies for the optimization of the synthesis of glycerol derived solvents . In: Green Chem. Band 19 , no. 17 , 2017, p. 4176-4185 , doi : 10.1039 / C7GC01583F .
- ↑ D. Sasseville, M. Stanciu: Allergic contact dermatitis from ethylhexylglycerin in sunscreens . In: dermatitis . tape 25 , no. 1 , 2014, p. 42-43 , doi : 10.1097 / DER.0b013e3182a5d8a9 .
- ↑ C. Harries, S. Mühlenbein, J. Geiger, W. Pfützner: Allergic contact dermatitis caused by ethylhexylglycerin in both an ointment and a skin aerosol . In: Contact Dermatitis . tape 74 , no. 3 , 2016, p. 181-182 , doi : 10.1111 / cod.12471 .
- ↑ O. Aerts, L. Verhulst, A. Goossens: Ethylhexylglycerin: a low-risk, but highly relevant, sensitizer in 'hypo-allergic' cosmetics . In: Contact Dermatitis . tape 74 , no. 5 , 2016, p. 281-288 , doi : 10.1111 / cod.12546 .