Tris(2,2,2-trifluoroethyl) borate

Names
IUPAC name

Tris(2,2,2-trifluoroethyl) borate[1]

Other names

* Boric acid tris(2,2,2-trifluoroethyl) ester[1]
* Sheppard amidation reagent[2]
* Sheppard reagent[2]
* Tris(2,2,2-trifluoroethoxy)borane[1]
* Tris(2,2,2-trifluoroethoxy)boron[2]

Identifiers

CAS Number

* 659-18-7

PubChem CID

* 3599767

Properties

Chemical formula

| B(OCH
2CF

Molar mass | 307.91 g·mol−1
Appearance  | Colourless liquid
Density | 1.430 g/cm3[3]
Boiling point |  94.3 °C (201.7 °F; 367.4 K)

Refractive index (nD)

| 1.298[2]
Hazards
Main hazards | Flammable liquid and vapor[1]
GHS pictograms |
GHS Signal word | Warning

GHS hazard statements

| HH226Script error: No such module "Preview warning".Category:GHS errors

GHS precautionary statements

| PP210Script error: No such module "Preview warning".Category:GHS errors, PP233Script error: No such module "Preview warning".Category:GHS errors, PP240Script error: No such module "Preview warning".Category:GHS errors, PP241Script error: No such module "Preview warning".Category:GHS errors, PP242Script error: No such module "Preview warning".Category:GHS errors, PP243Script error: No such module "Preview warning".Category:GHS errors, PP280Script error: No such module "Preview warning".Category:GHS errors, PP303+P361+P353Script error: No such module "Preview warning".Category:GHS errors, PP370+P378Script error: No such module "Preview warning".Category:GHS errors, PP403+P235Script error: No such module "Preview warning".Category:GHS errors, PP501Script error: No such module "Preview warning".Category:GHS errors
Flash point | 43.3 °C (109.9 °F)[3]

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Infobox references

Tris(2,2,2-trifluoroethyl) borate, also commonly referred to as the Sheppard amidation reagent,[2] is a chemical compound with the formula B(OCH
2CF

3. This borate ester reagent is used in organic synthesis.

## Contents

* 1 Preparation
* 2 Applications
* 3 References
* 4 Further reading

## Preparation

Tris(2,2,2-trifluoroethyl) borate can be prepared by reaction of trifluoroethanol with boron trichloride, borane dimethylsulfide, boron tribromide, or boric anhydride. The latter is more convenient for larger scale preparations due to its low cost and ease of handling.[4]

3CH
2OH + B

3 → B(OCH
2CF

The product is purified by distillation.

## Applications

The reagent is mostly used in condensation reactions. It has been shown to promote the direct formation of amides[4][5][6][7] from carboxylic acids and amines as well as the formation of imines[8] from amines or amides with carbonyl compounds.

It has also been used for the coupling of unprotected amino acids with amines.[clarification needed][6][9]

It has also been shown to mediate formylation of amines, via transamidation of dimethylformamide.

It is a strong Lewis acid (acceptor number = 66, Gutmann-Beckett method).[10]

## References

1. ↑ 1.0 1.1 1.2 1.3 https://pubchem.ncbi.nlm.nih.gov/compound/3599767
2. ↑ 2.0 2.1 2.2 2.3 2.4 "Tris(2,2,2-trifluoroethyl) borate 97% | Sigma-Aldrich". http://www.sigmaaldrich.com/catalog/product/aldrich/790877?lang=en&region=GB.
3. ↑ 3.0 3.1 https://www.sigmaaldrich.com/GB/en/sds/aldrich/790877
4. ↑ 4.0 4.1 Lanigan, Rachel M.; Starkov, Pavel; Sheppard, Tom D. (2013-05-03). "Direct Synthesis of Amides from Carboxylic Acids and Amines Using B(OCH2CF3)3". The Journal of Organic Chemistry 78 (9): 4512–4523. doi:10.1021/jo400509n. ISSN 0022-3263. PMID 23586467.
5. ↑ Karaluka, Valerija; Lanigan, Rachel M.; Murray, Paul M.; Badland, Matthew; Sheppard, Tom D. (2015-11-03). "B(OCH2CF3)3-mediated direct amidation of pharmaceutically relevant building blocks in cyclopentyl methyl ether" (in en). Organic & Biomolecular Chemistry 13 (44): 10888–10894. doi:10.1039/C5OB01801C. ISSN 1477-0539. PMID 26366853. http://discovery.ucl.ac.uk/1472232/1/47 CPME Amidation.pdf.
6. ↑ 6.0 6.1 Lanigan, Rachel M.; Karaluka, Valerija; Sabatini, Marco T.; Starkov, Pavel; Badland, Matthew; Boulton, Lee; Sheppard, Tom D. (2016-07-07). "Direct amidation of unprotected amino acids using B(OCH2CF3)3" (in en). Chemical Communications 52 (57): 8846–8849. doi:10.1039/C6CC05147B. ISSN 1364-548X. PMID 27346362.
7. ↑ Sabatini, Marco T.; Boulton, Lee T.; Sheppard, Tom D. (2017-09-01). "Borate esters: Simple catalysts for the sustainable synthesis of complex amides" (in en). Science Advances 3 (9): e1701028. doi:10.1126/sciadv.1701028. ISSN 2375-2548. PMID 28948222. Bibcode: 2017SciA....3E1028S.
8. ↑ Reeves, Jonathan T.; Visco, Michael D.; Marsini, Maurice A.; Grinberg, Nelu; Busacca, Carl A.; Mattson, Anita E.; Senanayake, Chris H. (2015-05-15). "A General Method for Imine Formation Using B(OCH2CF3)3". Organic Letters 17 (10): 2442–2445. doi:10.1021/acs.orglett.5b00949. ISSN 1523-7060. PMID 25906082.
9. ↑ Sabatini, Marco; Karaluka, Valerija; Lanigan, Rachel; Boulton, Lee; Badland, Matthew; Sheppard, Tom David (2018). "Protecting-group-free amidation of amino acids using Lewis acid catalysts" (in en). Chemistry - A European Journal 24 (27): 7033–7043. doi:10.1002/chem.201800372. ISSN 1521-3765. PMID 29505683.
10. ↑ Beckett, Michael A; Rugen-Hankey Martin P; Strickland, Gary C; Varma, K. Sukumar, Lewis acidity in haloalkyl orthoborate and metaborate esters, (2001) Phosphorus, Sulfur, and Silicon, 168, 437-440.

## Further reading

* Related reagent tris(2,2,2-trinitroethyl)borate: Klapötke, Thomas M.; Krumm, Burkhard; Rusan, Magdalena; Sabatini, Jesse J. (2014). "Improved green-light-emitting pyrotechnic formulations based on tris(2,2,2-trinitroethyl)borate and boron carbide". Chem. Commun. 50 (67): 9581–9583. doi:10.1039/c4cc04616a. PMID 25012058.

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*[CID]: Compound ID