Carbon Multiply Bonded to other Atoms

An oxygen doubly bonded to a carbon atom is the functional group called a carbonyl group. The carbon atom must be part of the carbon skeleton of a molecule: if it is at one end of the carbon chain, the carbonyl group will be also attached to a hydrogen. Such compounds are called aldehydes, <m:math display='block'> <m:semantics> <m:mrow> <m:mi>R</m:mi><m:mo>&#x2212;</m:mo><m:mover> <m:mi>C</m:mi> <m:mo>&#x2225;</m:mo> </m:mover> <m:mo>&#x2212;</m:mo><m:mi>H</m:mi><m:mo>.</m:mo> </m:mrow> </m:semantics> </m:math>]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\[R - \mathop C\limits^\parallel - H.\]$$ If the <m:math display='block'> <m:semantics> <m:mrow> <m:mo>&#x227B;</m:mo><m:mi>C</m:mi><m:mo>=</m:mo><m:mi>O</m:mi> </m:mrow> </m:math>]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\[ \succ C = O\]$$ group is part way along a carbon chain, being attached to two alkyl groups, the compound is called a ketone, <m:semantics> <m:mrow> <m:mi>R</m:mi><m:mo>&#x2212;</m:mo><m:mover> <m:mi>C</m:mi> <m:mo>&#x2225;</m:mo> </m:mover> <m:mo>&#x2212;</m:mo><m:msup> <m:mi>R</m:mi> <m:mo>&#x2032;</m:mo> </m:msup> <m:mo>.</m:mo> </m:mrow> </m:math>]]</EquationSource><EquationSource Format="TEX"><![CDATA[$\[R - \mathop C\limits^\parallel - R'.\]$$ In spite of the different names there are only slight differences in their chemistry, so the two types of compound are considered together. We shall see that nearly all the reactions occur at the carbonyl group, regardless of the nature of the alkyl groups.