Benzyl potassium

Benzylpotassium is an organopotassium compound with the formula C6H5CH2K. It is an orange powder. Like organo-alkali metal reagents in general, benzyl potassium is highly reactive, so much so that it reacts with most solvents. It is highly air sensitive.

Benzyl potassium
Names
Other names
Potassium benzyl
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/C7H7.K/c1-7-5-3-2-4-6-7;/h2-6H,1H2;
    Key: OQLLVOGBAKFMIS-UHFFFAOYSA-N
  • InChI=1/C7H7.K/c1-7-5-3-2-4-6-7;/h2-6H,1H2;/rC7H7K/c8-6-7-4-2-1-3-5-7/h1-5H,6H2
    Key: OQLLVOGBAKFMIS-QPGMTJJQAI
  • [K]Cc1ccccc1
Properties
C7H7K
Molar mass 130.231 g·mol−1
Appearance Orange solid
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Ignites in air
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Synthesis

One early synthesis proceeds by two-step transmetallation reaction via p-tolylpotassium:[1]

(CH3C6H4)2Hg + 2 K → 2 CH3C6H4K + Hg
CH3C6H4K → KCH2C6H5

A modern synthesis involves the reaction of butyllithium, potassium tert-butoxide, and toluene.[2] Although potassium hydride can also be used as a strong base for preparing potassium salts, benzyl potassium has the advantage of being molecular and hence more fast-acting.

References
  1. Gilman, Henry; Pacevitz, Henry A; Baine, Ogden (1940). "Benzylalkali Compounds1". Journal of the American Chemical Society. 62 (6): 1514. doi:10.1021/ja01863a054.
  2. Lochmann, L; Trekoval, J (1987). "Lithium-potassium exchange in alkyllithium/potassium t-pentoxide systems". Journal of Organometallic Chemistry. 326: 1. doi:10.1016/0022-328X(87)80117-1.
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