Hafnium trifluoromethanesulfonate

Hafnium(IV) Triflate

Names
IUPAC names

Hafnium(IV) trifluoromethanesulfonate

Identifiers

CAS Number

* 161337-67-3 Y

3D model (JSmol)

* Interactive image

ChemSpider |

* 21170913

EC Number |

* 624-948-5

PubChem CID

* 9853707

InChI

* InChI=1S/4CHF3O3S.Hf/c4*2-1(3,4)8(5,6)7;/h4*(H,5,6,7);/q;;;;+4/p-4

Key: BQYMOILRPDTPPJ-UHFFFAOYSA-J

SMILES

* C(F)(F)(F)S(=O)(=O)[O-].C(F)(F)(F)S(=O)(=O)[O-].C(F)(F)(F)S(=O)(=O)[O-].C(F)(F)(F)S(=O)(=O)[O-].[Hf+4]

Properties

Chemical formula

| Hf(OTf)4
Molar mass | 774.8 g/mol
Appearance  | Colourless solid
Melting point |  350 °C (662 °F; 623 K)
Hazards
Main hazards | irritantant
Safety data sheet | [1]
GHS pictograms |
GHS Signal word | Danger

GHS hazard statements

| H314, H315, H318, H319, H335

GHS precautionary statements

| P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P403+233, P405, P501
Flash point | Non-flammable
Related compounds

Other anions

| Hafnium tetrachloride
Hafnium tetrafluoride
Hafnium(IV) bromide
Hafnium(IV) iodide

Other cations

| Titanium(IV) triflate
Zirconium(IV) triflate

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

Y verify (what is YN ?)
Infobox references

Tracking categories (test):

* SizeSet

Hafnium(IV) triflate or hafnium trifluoromethansulfonate is an inorganic substance with the idealized formula Hf(OSO2CF3)4, also written as Hf(OTf)4. Hafnium triflate is used as an impure mixture as a catalyst. Hafnium (IV) has an ionic radius of intermediate range (Al < Ti < Hf < Zr < Sc < Ln) and has an oxophilic hard character typical of group IV metals. This solid is a stronger Lewis acid than its typical precursor hafnium tetrachloride, HfCl4, because of the strong electron-withdrawing nature of the four triflate groups, which makes it a great Lewis acid and has many uses including as a great catalyst at low Lewis acid loadings for electrophilic aromatic substitution and nucleophilic substitution reactions.[1]

## Contents

* 1 Preparation
* 2 Uses
* 2.1 Electrophilic Substitutions
* 2.2 Nucleophilic Substitutions
* 3 References

## Preparation

The compound was first synthesized by the Kobayashi group in 1995 via the reaction of HfCl4 and triflic acid.[2] This solid is air stable, easy to handle, and commercially available.[3]

## Uses

### Electrophilic Substitutions

Hf(OTf)4 catalyzed Friedel-Craft acylation and alkylation reactions

Friedel-Craft acylation or alkylation reactions are some of the most important synthetic methodologies to introduce carbonyl or alkyl groups onto aromatic compounds.[4] The first Hf(OTf)4 catalyzed Friedel-Crafts acylation was developed by Kobayashi et al. in 1995.[2][5] The authors demonstrated that Friedel-Crafts acylation could be achieved in excellent yield between arenes and acid anhydrides when utilizing Hf(OTf)4 as a catalyst. Hf(OTf)4, was the most effective in comparison to other Lewis acids including BF3 • OEt2, Sc(OTf)3, and Zr(OTf)4. Similalrly, Hf(OTf)4 shows excellent activity in Friedel-Crafts alkylation’s, and enabled the alkylation of benzene with benzylic and tertiary alkyl chlorides.

Hf(OTf)4-catalyzed Friedel-Crafts alkylation has been utilized in the total synthesis of the altertoxin III framework. This approach provided a more efficient synthesis of the fused-ring structure compared to previous methods.[6]

Hf(OTf)4 mediated synthesis of altertoxins

Hf(OTf)4, alongside Sc(OTf)3 and In(OTf)3, has been shown to activate alkynes and enable electrophilic substitution. In 2004 Song and Lee et al. reported Hf(OTf)4-catalyzed Friedel-Crafts alkenylation of benzene with alkenyl derivatives.[7]

Hf(OTf)4 enabled electrophilic substitution of alkynes

### Nucleophilic Substitutions

In 2008, Zhu et al. demonstrated that Hf(OTf)4 was an effective catalyst for the thioacetalization of aldehydes and ketones.[8] In the absence of Lewis acid this reaction can occur in glycerol at 90 °C. Hf(OTf)4 accelerated the reaction rate under milder conditions with only 0.1 mol% catalyst loading. For example, Hf(OTf)4 catalyzes the reaction between benzaldehyde and 2.0 equiv. of either ethanethiol or 1.0 equiv. of propane-1,3,-dithiol readily in quantitative yield.

Hf(OTf)4 catalyzed thioacetalization of benzaldehyde

This methodology was utilized in the total synthesis of (-)-leucomidine B from an enantioenriched monoacid synthesized via a Hf(OTf)4 catalyzed thioacetalization.[9]

Total synthesis of (-)-leucomidine B

In 2009, Nakamura et al. demonstrated that Hf(OTf)4 was uniquely able to catalyzed a Prins reaction between an aryl aldehyde and an O-protected/unprotected cyclohex-3-ene-1,2-dimethanol.[10]

Hf(OTf)4 catalyzed Prins cyclization

## References

1. ↑ Ishitani, Haruro; Suzuki, Hirotsugu; Saito, Yuki; Yamashita, Yasuhiro; Kobayashi, Shū (2015). "Hafnium Trifluoromethanesulfonate [Hf(OTf)4 as a Unique Lewis Acid in Organic Synthesis"] (in en). European Journal of Organic Chemistry 2015 (25): 5485–5499. doi:10.1002/ejoc.201500423. ISSN 1099-0690. https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/ejoc.201500423.
2. ↑ 2.0 2.1 Hachiya, Iwao; Moriwaki, Mitsuhiro; Kobayashi, Shu (1995-07-01). "Hafnium(IV) Trifluoromethanesulfonate, An Efficient Catalyst for the Friedel–Crafts Acylation and Alkylation Reactions". Bulletin of the Chemical Society of Japan 68 (7): 2053–2060. doi:10.1246/bcsj.68.2053. ISSN 0009-2673. https://www.journal.csj.jp/doi/10.1246/bcsj.68.2053.
3. ↑ Li, Zhiya; Plancq, Baptiste; Ollevier, Thierry (2011) (in en), Hafnium(IV) Trifluoromethanesulfonate, American Cancer Society, doi:10.1002/047084289x.rn01315, ISBN 978-0-470-84289-8, https://onlinelibrary.wiley.com/doi/abs/10.1002/047084289X.rn01315, retrieved 2021-06-12
4. ↑ Calloway, N. O. (1935-12-01). "The Friedel-Crafts Syntheses.". Chemical Reviews 17 (3): 327–392. doi:10.1021/cr60058a002. ISSN 0009-2665. https://doi.org/10.1021/cr60058a002.
5. ↑ Hachiya, Iwao; Moriwaki, Mitsuhiro; Kobayashi, Shu (1995-01-16). "Catalytic Friedel-Crafts acylation reactions using hafnium triflate as a catalyst in lithium perchlorate-nitromethane" (in en). Tetrahedron Letters 36 (3): 409–412. doi:10.1016/0040-4039(94)02221-V. ISSN 0040-4039. https://www.sciencedirect.com/science/article/abs/pii/004040399402221V.
6. ↑ Geiseler, Oliver; Müller, Monika; Podlech, Joachim (2013-05-06). "Synthesis of the altertoxin III framework" (in en). Tetrahedron 69 (18): 3683–3689. doi:10.1016/j.tet.2013.03.013. ISSN 0040-4020. https://www.sciencedirect.com/science/article/abs/pii/S0040402013003633.
7. ↑ Song, Choong Eui; Jung, Da-un; Choung, Su Yhen; Roh, Eun Joo; Lee, Sang-gi (2004). "Dramatic Enhancement of Catalytic Activity in an Ionic Liquid: Highly Practical Friedel–Crafts Alkenylation of Arenes with Alkynes Catalyzed by Metal Triflates". Angewandte Chemie International Edition 43 (45): 6183–6185. doi:10.1002/anie.200460292. ISSN 1521-3773. PMID 15549737. https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.200460292.
8. ↑ Wu, Yan-Chao; Zhu, Jieping (2008-12-05). "Hafnium Trifluoromethanesulfonate (Hafnium Triflate) as a Highly Efficient Catalyst for Chemoselective Thioacetalization and Transthioacetalization of Carbonyl Compounds". The Journal of Organic Chemistry 73 (23): 9522–9524. doi:10.1021/jo8021988. ISSN 0022-3263. PMID 18991383. https://doi.org/10.1021/jo8021988.
9. ↑ Gualtierotti, Jean-Baptiste; Pasche, Delphine; Wang, Qian; Zhu, Jieping (2014). "Phosphoric Acid Catalyzed Desymmetrization of Bicyclic Bislactones Bearing an All-Carbon Stereogenic Center: Total Syntheses of (−)-Rhazinilam and (−)-Leucomidine B" (in en). Angewandte Chemie International Edition 53 (37): 9926–9930. doi:10.1002/anie.201405842. ISSN 1521-3773. PMID 25048385. https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201405842.
10. ↑ Nakamura, Masayuki; Niiyama, Kenji; Yamakawa, Takeru (2009-11-25). "Versatile method for the synthesis of 4-substituted 6-methyl-3-oxabicyclo[3.3.1non-6-ene-1-methanol derivatives: Prins-type cyclization reaction catalyzed by hafnium triflate"] (in en). Tetrahedron Letters 50 (47): 6462–6465. doi:10.1016/j.tetlet.2009.08.120. ISSN 0040-4039. https://www.sciencedirect.com/science/article/abs/pii/S0040403909016943.

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*[CID]: Compound ID
*[H314]: Causes severe skin burns and eye damage
*[H315]: Causes skin irritation
*[H318]: Causes serious eye damage
*[H319]: Causes serious eye irritation
*[H335]: May cause respiratory irritation
*[P261]: Avoid breathing dust/fume/gas/mist/vapours/spray
*[P264]: Wash … thoroughly after handling
*[P271]: Use only outdoors or in a well-ventilated area
*[P280]: Wear protective gloves/protective clothing/eye protection/face protection
*[P302+352]: IF ON SKIN: Wash with soap and water
*[P304+340]: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
*[P305+351+338]: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing
*[P312]: Call a POISON CENTER or doctor/physician if you feel unwell
*[P321]: Specific treatment (see … on this label)
*[P332+313]: If skin irritation occurs: Get medical advice/attention
*[P337+313]: Get medical advice/attention
*[P362]: Take off contaminated clothing and wash before reuse
*[P403+233]: Store in a well ventilated place. Keep container tightly closed
*[P405]: Store locked up
*[P501]: Dispose of contents/container to …