Benzyl potassium: Difference between revisions

Benzyl potassium
Names
	Other names Potassium benzyl
Identifiers
CAS Number	2785-29-7;
3D model (JSmol)	Interactive image;
ChemSpider	10675000;
PubChem CID	11083915;
CompTox Dashboard (EPA)	DTXSID00454524 ;
	InChI 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;
	SMILES [K]Cc1ccccc1;
Properties
Chemical formula	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

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Benzylpotassium is an organopotassium compound with the formula C₆H₅CH₂K, 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.

Synthesis

One early synthesis proceeds by two-step transmetallation reaction by 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

^ Gilman, Henry; Pacevitz, Henry A; Baine, Ogden (1940). "Benzylalkali Compounds1". Journal of the American Chemical Society. 62 (6): 1514. doi:10.1021/ja01863a054.
^ 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.

[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.

[1]

[2]

@@ Line 1: / Line 1: @@
 {{Chembox
-| ImageFile =
+| Name =
+| ImageFile = Kbenzyl.svg
-|  ImageSize =
-|  ImageAlt =
+| ImageSize = 100px
-| IUPACName =
+| ImageAlt =
 | OtherNames = Potassium benzyl
+| SystematicName =
 | Section1 = {{Chembox Identifiers
-|  CASNo = 2785-29-7
+| CASNo = 2785-29-7
-|  PubChem =
+| PubChem = 11083915
+| ChemSpiderID = 10675000
-|  SMILES = }}
+| SMILES = [K]Cc1ccccc1
+| 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
+| InChIKey = OQLLVOGBAKFMIS-QPGMTJJQAI
+| StdInChI = 1S/C7H7.K/c1-7-5-3-2-4-6-7;/h2-6H,1H2;
+| StdInChIKey = OQLLVOGBAKFMIS-UHFFFAOYSA-N }}
 | Section2 = {{Chembox Properties
+| C=7|H=7|K=1
-|  Formula = C<sub>7</sub>H<sub>7</sub>K
+| Appearance = Orange solid}}
-|  MolarMass = 130.23
-|  Appearance = orange solid
-|  Density =
-|  MeltingPt =
-|  BoilingPt =
-|  Solubility = }}
 | Section3 = {{Chembox Hazards
-|  MainHazards = ignites in air
+| MainHazards = Ignites in air
-|  FlashPt =
+| FlashPt =
-|  Autoignition = }}
+| AutoignitionPt =}}
 }}
-'''Benzyl potassium''' is an [[organopotassium compound]] with the formula C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>K.  It is an orange solid that is so extremely basic that it is compatible only with hydrocarbon solvent.  It was originally prepared by two-step [[transmetallation reaction]] via p-tolyl sodium:<ref>Gilman, Henry; Pacevitz, Henry A.; Baine, Ogden "Benzylalkali Compounds" Journal of the American Chemical Society 1940, vol. 62, pp. 1514-20.  {{DOI|10.1021/ja01863a054}}</ref>
+'''Benzylpotassium''' is an [[organopotassium compound]] with the formula C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>K, 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.
-:(CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>Hg  +  2 K   →   2 CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>K   +  Hg
+==Synthesis==
-:CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>K    →   KCH<sub>2</sub>C<sub>6</sub>H<sub>5</sub>
+One early synthesis proceeds by two-step [[transmetallation reaction]] by ''p''-tolylpotassium:<ref>{{cite journal |doi = 10.1021/ja01863a054|title = Benzylalkali Compounds1|journal = Journal of the American Chemical Society|volume = 62|issue = 6|pages = 1514|year = 1940|last1 = Gilman|first1 = Henry|last2 = Pacevitz|first2 = Henry A|last3 = Baine|first3 = Ogden}}</ref>
-A modern synthesis involves the reaction of [[butyllithium]], [[potassium tert-butoxide]], and [[toluene]].<ref>Philip J. Bailey, Robert A. Coxall, Caroline M. Dick, Sylvie Fabre, Louise C. Henderson,
+:(CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>Hg + 2 K → 2 CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>K + Hg
-Christian Herber, Stephen T. Liddle, Daniel Loroño-Gonzālez, Andrew Parkin, Simon Parsons "The First Structural Characterisation of a Group 2 Metal Alkylperoxide Complex: Comments on the Cleavage of Dioxygen by Magnesium Alkyl Complexes"  Chemistry, European Journal 2003, vol. 9, pp. 4820 ± 4828.  {{DOI|10.1002/chem.200305053}}</ref>  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.
+:CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>K → KCH<sub>2</sub>C<sub>6</sub>H<sub>5</sub>
+A modern synthesis involves the reaction of [[butyllithium]], [[potassium tert-butoxide|potassium ''tert''-butoxide]], and [[toluene]].<ref>{{cite journal | doi = 10.1016/0022-328X(87)80117-1| title = Lithium-potassium exchange in alkyllithium/potassium t-pentoxide systems| journal = Journal of Organometallic Chemistry| volume = 326| pages = 1| year = 1987| last1 = Lochmann| first1 = L| last2 = Trekoval| first2 = J}}</ref> 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==
 <references />
 [[Category:Potassium compounds]]
+[[Category:Benzyl compounds]]