ε-caprolactone

Structural formula
General
Surname	ε-caprolactone
other names	ε-lactone 6-hydroxyhexanoic acid lactone 6-hydroxycaproic acid lactone 6-caprolactone Hexanolactone 6-hexanolide 2-oxepanone Hexanoic acid-epsilon-lactone Caprolactone
Molecular formula	C 6 H 10 O 2
Brief description	colorless liquid
External identifiers / databases
CAS number 502-44-3 EC number 207-938-1 ECHA InfoCard 100.007.217 PubChem 10401 Wikidata Q288104
properties
Molar mass	114.14 g mol −1
Physical state	liquid
density	1.08 g cm −3 (20 ° C)
Melting point	−1.5 ° C
boiling point	235 ° C
Vapor pressure	1.3 Pa (20 ° C)
solubility	miscible with water
Refractive index	1.463 (20 ° C)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 319 P: 280-305 + 351 + 338-337 + 313
Toxicological data	5990 mg · kg -1 ( LD 50 ,  rabbit ,  transdermally )
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

ε-caprolactone , also ε-lactone or caprolactone, is a chemical compound from the group of cyclic carboxylic acid esters , which are referred to as lactones . Caprolactone has a seven-membered ring with six carbon atoms, like the hexanoic acid on which caprolactone is based, which is also called caproic acid .

Manufacturing

There are a number of ways to synthesis known of caprolactone, which can be divided into two groups. On the one hand, the production starting from open-chain compounds, such as. B. derivatives of hexane possible, on the other hand the oxidative ring expansion of cyclic ketones .

Starting from open-chain compounds, for example 6-hydroxyhexanoic acid , 1,6-hexanediol or adipic acid can be used.

Starting from cyclic compounds , caprolactone can be produced by a Baeyer-Villiger oxidation of cyclohexanone with peracids such as peracetic acid , perbenzoic acid or m -chloroperbenzoic acid. The oxidation can, however, also be brought about by means of catalysts using oxygen .

properties

Caprolactone is a colorless liquid that solidifies at −1.5 ° C and boils at 235 ° C. It has a dynamic viscosity of 6.67 mPa‣s at 20 ° C. Their flash point is 127 ° C, their ignition temperature 204 ° C. In the range from 1.2 to 9 percent by volume, it forms explosive mixtures with air . It starts to decompose at temperatures above 220 ° C.

use

Caprolactone is used as a raw material for the production of polycaprolactone , a plastic from the group of thermoplastics .

Production of polyesters from ε-caprolactone

Caprolactone can easily be opened by Lewis acids or Brønsted acids , which enables the production of hexane derivatives.

Individual evidence

1. ↑ ^{a b c d e f g h} Entry on epsilon-caprolactone in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
2. ↑ ε-Caprolactone data sheet from Sigma-Aldrich , accessed on April 26, 2011 ( PDF ).
3. ↑ ^{a b c d e} data sheet ε-caprolactone (PDF) at Merck , accessed on 27 February 2010 .
4. ^ ^{A b} F. J. van Natta, JW Hill, WH Carothers: Studies of Polymerization and Ring Formation. ε-Caprolactone and its Polymers , in: J. Am. Chem. Soc. , 1934 , 56 , p. 455.
5. ↑ W. Reppe: ethynylation VI , in: Liebigs Ann. , 1955 , 596 , 1, pp. 158-224.
6. ^ U. Matteoli, G. Menchi, M. Bianchi, P. Frediani, F. Piacenti: Gazzetta Chimica Italiana , 1985 , 115 , pp. 603-606.
7. ↑ PS Starcher, B. Phillips: Synthesis of Lactones , in: J. Am. Chem. Soc. , 1958 , 80 , pp. 4079-4082.
8. ^ SL Friess: Reactions of Per Acids. II. The Reaction of Perbenzoic Acid with Simple Cyclic Ketones. Kinetic Studies , in: J. Am. Chem. Soc. , 1949 , 71 , pp 2571-2572.
9. ↑ S. Horvat, P. Karallas, JM White: Reactions of β-trimethylstannylcyclohexanones with peracids: investigations into the stannyl-directed Baeyer-Villiger reaction , in: J. Chem Soc, Perkin Trans. 2.. , 1998 , 10 , S 2151-2154.
10. ↑ C. Bolm, G. Schlingloff, K. Weickhardt: Use of molecular oxygen in the Baeyer-Villiger oxidation the influence of metal catalysts , in: Tetrahedron Letters , 1993 , 34 , pp 3405-3408.
11. ↑ S.-I. Murahashi, Y. Oda, T. Naota: Fe ₂ O ₃ -catalyzed baeyer-villiger oxidation of ketones with molecular oxygen in the presence of aldehydes , in: Tetrahedron Letters , 1992 , 33 , pp. 7557-7560.