1- (Trifluoromethyl) -1,2-benziodoxol-3 (1 H ) -one

Structural formula
General
Surname	1- (Trifluoromethyl) -1,2-benziodoxol-3 (1H) -one
other names	Togni reagent II
Molecular formula	C 8 H 4 F 3 IO 2
Brief description	colorless, crystalline solid
External identifiers / databases
CAS number 887144-94-7 EC number 688-223-5 ECHA InfoCard 100.214.822 PubChem 24850981 ChemSpider 24807962 Wikidata Q15632697
properties
Molar mass	316.02 g mol −1
Physical state	firmly
Melting point	122.4–123.4 ° C (with decomposition)
solubility	soluble in methylene chloride, chloroform, acetonitrile, methanol, ethanol, acetone
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

1- (Trifluoromethyl) -1,2-benziodoxol-3 (1 H ) -one (Togni reagent II) is a compound used in organic synthesis for direct electrophilic trifluoromethylation .

history

The first description of the production, properties and reactivity of the compound was made in 2006 by Antonio Togni and his colleagues from ETH Zurich . The article also provides information on 1,3-dihydro-3,3-dimethyl-1- (trifluoromethyl) -1,2-benziodoxol (Togni's reagent I).

Extraction and presentation

The synthesis takes place in a three-step process. In the first step 2-iodobenzoic acid in the presence of sodium periodate an oxidation and cyclization to give the mixed anhydride 1-hydroxy-1,2-benziodoxol-3 (1 H implemented) -one. By acylation with acetic anhydride and subsequent substitution with trimethyl (trifluoromethyl) silane , the target compound is produced.

A more recent one-pot synthesis also starts from 2-iodobenzoic acid. Trichloroisocyanuric acid is used as the oxidizing agent instead of sodium periodate .

properties

Physical Properties

The compound crystallizes in a monoclinic crystal structure. The space group is P2 ₁ / n with four molecules in the unit cell . A density of 2.365 g · cm ^{−3 was} derived from the crystallographic data .

Chemical properties

The pure compound is thermally stable for months at room temperature. Violent decomposition occurs above the melting point, releasing gaseous trifluoroiodomethane . The decomposition is highly exothermic. In a DSC measurement , a heat of decomposition of 502 J g ^{−1 was} determined from 149 ° C. Small amounts of trifluoromethyl-2-iodobenzoates and 2-iodobenzoyl fluoride were observed as decomposition products during recrystallization from acetonitrile . The tests regarding explosive properties are positive for the steel sleeve test and the impact sensitivity , negative for the friction sensitivity. It is therefore an explosive substance. The compound reacts violently with strong bases and acids, as well as reducing agents. Its polymerization is initiated in the solvent tetrahydrofuran .

use

The compound is used to introduce the CF ₃ group into organic compounds. In the case of phenolates, there is a substitution in the ortho position. With an excess, a twofold substitution can be achieved.

The corresponding trifluoromethyl ethers are obtained with alcohols .

The CF ₃ function can be added to terminal olefins with copper catalysis .

Individual evidence

1. ↑ ^{a b c d e f g h} Kyrill Stanek, Raffael Koller, Iris Kieltsch, Patrick Eisenberger, Antonio Togni: 1- (Trifluoromethyl) -1,2-benziodoxol-3 (1H) -one . In: Encyclopedia of Reagents for Organic Synthesis . John Wiley & Sons, Ltd, 2001, ISBN 978-0-470-84289-8 , doi : 10.1002 / 047084289X.rn01121 .
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ↑ I. Kieltsch, P. Eisenberger, K. Stanek, A. Togni: Recent Advances in Electrophilic CF ₃ -Transfer Using hypervalent Iodine (III) Reagents. In: Chimia . 62, 2008, pp. 260-263, doi: 10.2533 / chimia.2008.260 .
4. ↑ ^{a b c} Patrick Eisenberger, Sebastian Gischig, Antonio Togni: Novel 10-I-3 Hypervalent Iodine-Based Compounds for Electrophilic Trifluoromethylation . In: Chemistry - A European Journal . tape 12 , no. 9 , 2006, p. 2579-2586 , doi : 10.1002 / chem.200501052 .
5. ↑ Václav Matoušek, Ewa Pietrasiak, Rino Schwenk, Antonio Togni: One-Pot Synthesis of Hypervalent Iodine Reagents for Electrophilic Trifluoromethylation . In: The Journal of Organic Chemistry . tape 78 , no. 13 , 2013, p. 6763-6768 , doi : 10.1021 / jo400774u .
6. ↑ ^{a b} Nikolaus Fiederling, Jan Haller, Heiko Schramm: Notification about the Explosive Properties of Togni's Reagent II and One of Its precursor . In: Organic Process Research & Development . tape 17 , no. 3 , 2013, p. 318-319 , doi : 10.1021 / op400035b .
7. ↑ Devoille, A .; Haller, J .: Facing the unknown with confidence: working with unidentified hazardous properties of chemical reagents in Chemistry Today 32 (3) May / June 2014, 47-50.
8. ↑ Kyrill Stanek, Raffael Koller, Antonio Togni: Reactivity of a 10-I-3 Hypervalent Iodine Trifluoromethylation Reagent With Phenols . In: The Journal of Organic Chemistry . tape 73 , no. 19 , 2008, p. 7678-7685 , doi : 10.1021 / jo8014825 .
9. ↑ Raffael Koller, Kyrill Stanek, Daniel Stolz, Raphael Aardoom, Katrin Niedermann, Antonio Togni: Zinc-Mediated Formation of Trifluoromethyl Ethers from Alcohols and Hypervalent Iodine Trifluoromethylation Reagents . In: Angewandte Chemie . tape 121 , no. 24 , 2009, p. 4396-4400 , doi : 10.1002 / anie.200900974 .
10. ↑ Andrew T. Parsons, Stephen L. Buchwald: Copper-Catalyzed Trifluoromethylation of Unactivated Olefins . In: Angewandte Chemie . tape 123 , no. 39 , 2011, p. 9286-9289 , doi : 10.1002 / anie.201104053 .