Carbon–oxygen bond

A carbon–oxygen bond is a covalent bond between carbon and oxygen. ^[1] ^[2] ^[3] Oxygen has 6 valence electrons and prefers to either share two electrons in bonding with carbon, leaving the 4 nonbonding electrons in 2 lone pairs :Ó: or to share two pairs of electrons to form the carbonyl functional group. =O: Simple representatives of these two bond types are the ^_OH in alcohols such as the ethanol in beverages and fuels and the C=O in ketones (as well as many other related carbonyl compounds).^[4]

Electronegativities and bond lengths

The C–O bond is strongly polarized towards oxygen (electronegativity of C vs O, 2.55 vs 3.44). Bond lengths for paraffinic C–O bonds are in the range of 143 picometer – less than those of C–N or C–C bonds. Shortened single bonds are found with carboxylic acids (136 pm) due to partial double bond character and elongated bonds are found in epoxides (147 pm).^[5] The C–O bond strength is also larger than C–N or C–C. For example, bond strengths are 91 kcal/mol (at 298 K) in methanol, 87 kcal/mol in methylamine, and 88 kcal/mol in ethane. ^[5]

Carbon and oxygen form terminal double bonds in functional groups collectively known as carbonyl compounds to which belong such compounds as ketones, esters, carboxylic acids and many more. Internal C=O bonds are found in positively charged oxonium ions. In furans, the oxygen atom contributes to pi-electron delocalization via its filled p-orbital and hence furans are aromatic. Bond lengths of C=O bonds are around 123 pm in carbonyl compounds. The C=O bonds in acyl halides have partial triple bond character and are subsequently very short: 117 pm. Compounds with formal C–O triple bonds do not exist except for carbon monoxide, which has a very short, strong bond (112.8 pm). Such triple bonds have a very high bond energy, even higher than N–N triple bonds.^[6] Oxygen can also be trivalent, for example in triethyloxonium tetrafluoroborate.

Chemistry

Carbon–oxygen bond forming reactions are the Williamson ether synthesis, nucleophilic acyl substitutions and electrophilic addition to alkenes. The Paternò–Büchi reaction involves carbonyl compounds.

Oxygen functional groups

Carbon–oxygen bonds are present in these functional groups:

Chemical class	Bond order	Formula	Structural Formula	Example
Alcohols	1	R₃C–OH		Ethanol
Ethers	1	R₃C–O–CR₃		Diethyl ether
Peroxides	1	R₃C–O–O–CR₃		Di-tert-butyl peroxide
Esters	1	R₃C–CO–O–CR₃		Ethyl acrylate Ethyl acrylate
Carbonate esters	1	R₃C–O–CO–O–CR₃	Carbonate ester	Ethylene carbonate Ethylene carbonate
Ketones	2	R₃C–CO–CR₃	Ketone	Acetone
Aldehydes	2	R₃C–CHO		Acrolein
Furans	1.5			Furfural
Pyrylium salts	1.5		pyridine	Anthocyanin Anthocyanins

References

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↑ Organic Chemistry John McMurry 2nd Ed.^{[page needed]}
↑ March, J.; Smith, D. (2001). Advanced Organic Chemistry, 5th ed. New York: Wiley.
↑ Advanced Organic Chemistry Carey, Francis A., Sundberg, Richard J. 5th ed. 2007
↑ Lua error in package.lua at line 80: module 'strict' not found.
↑ ^5.0 ^5.1 CRC Handbook of Chemistry and Physics 65Th Ed.
↑ Standard Bond Energies, Department of Chemistry, Michigan State University

[1] Organic Chemistry John McMurry 2nd Ed.^{[page needed]}

[2] March, J.; Smith, D. (2001). Advanced Organic Chemistry, 5th ed. New York: Wiley.

[3] Advanced Organic Chemistry Carey, Francis A., Sundberg, Richard J. 5th ed. 2007

[4] Lua error in package.lua at line 80: module 'strict' not found.

[crc-5] 5.0 ^5.1 CRC Handbook of Chemistry and Physics 65Th Ed.

[6] Standard Bond Energies, Department of Chemistry, Michigan State University

[1]

[2]

[3]

[4]

[5]

[6]

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	CRa		Rf	Db	CSg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Fl	Uup	Lv	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	CTh	CPa	CU	CNp	CPu	CAm	CCm	CBk	CCf	CEs	Fm	Md	No	Lr

Core organic chemistry	Many uses in chemistry
Academic research, but no widespread use	Bond unknown

Carbon–oxygen bond

Contents

Electronegativities and bond lengths

Chemistry

Oxygen functional groups

See also

References

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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	CRa		Rf	Db	CSg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Fl	Uup	Lv	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	CTh	CPa	CU	CNp	CPu	CAm	CCm	CBk	CCf	CEs	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	CRa		Rf	Db	CSg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Fl	Uup	Lv	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	CTh	CPa	CU	CNp	CPu	CAm	CCm	CBk	CCf	CEs	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	CRa		Rf	Db	CSg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Fl	Uup	Lv	Uus	Uuo
		↓
		CLa	CCe	CPr	CNd	CPm	CSm	CEu	CGd	CTb	CDy	CHo	CEr	CTm	CYb	CLu
		Ac	CTh	CPa	CU	CNp	CPu	CAm	CCm	CBk	CCf	CEs	Fm	Md	No	Lr