Organosodium chemistry

Organosodium chemistry is the chemistry of organometallic compounds containing a carbon to sodium chemical bond.^[1]^[2] The application of organosodium compounds in chemistry is limited in part due to competition from organolithium compounds in the same group 1 elements row of the periodic table. Yet several important compounds exist.

Organometal bonds in group 1 are characterised by high polarity and high nucleophilicity on carbon (compare electronegativity of carbon (2.55) to that of lithium 0.98, sodium 0.93 potassium 0.82 rubidium 0.82). The principal organosodium compound of importance is sodium cyclopentadienide that is prepared from sodium metal and cyclopentadiene:

2 Na + 2 C₅H₆ → 2 NaC₅H₅ + H₂

The higher alkali metals are known to metalate even some unactivated hydrocarbons and are known to self-metalate

2 NaC₂H₅ → C₂H₄Na₂ + C₂H₆

Some organosodium compounds degrade by beta-elimination:

NaC₂H₅ → NaH + C₂H₄

The carbanionic nature of organosodium compounds can be minimized by resonance stabilization. For instance in Ph₃CM compounds is rather stable and is even used as a reagent.^[3]

Sodium also react with polycyclic aromatic hydrocarbon via one-electron reduction. With solutions of naphthalene, it forms the deeply coloured radical sodium naphthalenide.

C₁₀H₈ + Na → Na⁺[C₁₀H₈]^-•

In the Wanklyn reaction (1858) ^[4]^[5] sodium replaces magnesium in a Grignard type reaction with carbon dioxide:

C₂H₅Na + CO₂ → C₂H₅CO₂Na

In the original work the alkylsodium compound was accessed from the dialkylmercury compound by transmetallation. For example diethylmercury in the Schorigin reaction or Shorygin Reaction:^[6] ^[7]

(C₂H₅)₂Hg + 2Na → 2C₂H₅Na

Industrial applications

Although organosodium chemistry has been described to be of "little industrial importance", it once was central to the production of tetraethyllead.^[8] A similar Wurtz coupling-like reaction is the basis of the current industrial route to triphenylphosphine:

3 PhCl + PCl₃ + 6 Na → PPh₃ + 6 NaCl

Organic derivatives of the heavier alkali metals

The higher alkali metals, organopotassium, organorubidium and organocaesium, are even more reactive than organosodium compounds and of limited utility. A notable reagent is Schlosser's base, a mixture of n-butyllithium and potassium tert-butoxide. This reagent reacts with propene to the compound allyl potassium (KCH₂CHCH₂). cis-2-Butene and trans-2-butene equilibrate when in contact with alkali metals. Whereas isomerization is fast with lithium and sodium, it is slow with the higher alkali metals. The higher alkali metals also favor the sterically congested conformation.^[9]

References

^ Synthesis of Organometallic Compounds: A Practical Guide Sanshiro Komiya Ed. 1997
^ C. Elschenbroich, A. Salzer Organometallics : A Concise Introduction (2nd Ed) (1992) from Wiley-VCH: Weinheim. ISBN 3-527-28165-7
^ W. B. Renfrow, Jr and C. R. Hauser (1943), "Triphenylmethylsodium", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV2P0607 ; Coll. Vol. 2: 607
^ J. A. Wanklyn, Ann. 107, 125 (1858)
^ The Merck index of chemicals and drugs: an encyclopedia for chemists, Paul G. Stecher
^ P. Schorigin, Ber. 40, 3111 (1907)
^ P. Schorigin, Ber. 41, 2711, 27l7, 2723 (1908)
^ Rolf Ackermann, Ludwig Lange "Sodium Compounds, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a24_341
^ Manfred Schlosser (1988). "Superbases for organic synthesis". Pure and Appl. Chem. 60 (11): 1627–1634. doi:10.1351/pac198860111627.

CH																	He
CLi	CBe											CB	CC	CN	CO	CF	Ne
CNa	CMg											CAl	CSi	CP	CS	CCl	CAr
CK	CCa	CSc	CTi	CV	CCr	CMn	CFe	CCo	CNi	CCu	CZn	CGa	CGe	CAs	CSe	CBr	CKr
CRb	CSr	CY	CZr	CNb	CMo	CTc	CRu	CRh	CPd	CAg	CCd	CIn	CSn	CSb	CTe	CI	CXe
CCs	CBa		CHf	CTa	CW	CRe	COs	CIr	CPt	CAu	CHg	CTl	CPb	CBi	CPo	CAt	Rn
Fr	Ra		Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Uuq	Uup	Uuh	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	Th	Pa	CU	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr

**Chemical bonds to carbon**
Core organic chemistry	Many uses in chemistry
Academic research, but no widespread use	Bond unknown / not assessed

CH																	He
CLi	CBe											CB	CC	CN	CO	CF	Ne
CNa	CMg											CAl	CSi	CP	CS	CCl	CAr
CK	CCa	CSc	CTi	CV	CCr	CMn	CFe	CCo	CNi	CCu	CZn	CGa	CGe	CAs	CSe	CBr	CKr
CRb	CSr	CY	CZr	CNb	CMo	CTc	CRu	CRh	CPd	CAg	CCd	CIn	CSn	CSb	CTe	CI	CXe
CCs	CBa		CHf	CTa	CW	CRe	COs	CIr	CPt	CAu	CHg	CTl	CPb	CBi	CPo	CAt	Rn
Fr	Ra		Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Uuq	Uup	Uuh	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	Th	Pa	CU	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr

CH																	He
CLi	CBe											CB	CC	CN	CO	CF	Ne
CNa	CMg											CAl	CSi	CP	CS	CCl	CAr
CK	CCa	CSc	CTi	CV	CCr	CMn	CFe	CCo	CNi	CCu	CZn	CGa	CGe	CAs	CSe	CBr	CKr
CRb	CSr	CY	CZr	CNb	CMo	CTc	CRu	CRh	CPd	CAg	CCd	CIn	CSn	CSb	CTe	CI	CXe
CCs	CBa		CHf	CTa	CW	CRe	COs	CIr	CPt	CAu	CHg	CTl	CPb	CBi	CPo	CAt	Rn
Fr	Ra		Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Uuq	Uup	Uuh	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	Th	Pa	CU	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr

CH																	He
CLi	CBe											CB	CC	CN	CO	CF	Ne
CNa	CMg											CAl	CSi	CP	CS	CCl	CAr
CK	CCa	CSc	CTi	CV	CCr	CMn	CFe	CCo	CNi	CCu	CZn	CGa	CGe	CAs	CSe	CBr	CKr
CRb	CSr	CY	CZr	CNb	CMo	CTc	CRu	CRh	CPd	CAg	CCd	CIn	CSn	CSb	CTe	CI	CXe
CCs	CBa		CHf	CTa	CW	CRe	COs	CIr	CPt	CAu	CHg	CTl	CPb	CBi	CPo	CAt	Rn
Fr	Ra		Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Uuq	Uup	Uuh	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	Th	Pa	CU	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr