What are Functional Groups
Reactivity of Functional Groups Reactivity of Functional Groups
O O + Tollen's Reagent + silver mirror 2 Li + 2 H2O → 2 LiOH + H2 C C H CH3 HO CH3 2 Na + 2 H2O → 2 NaOH + H2 O O + silver mirror 2 K + 2 H2O → 2 KOH + H2 C + Tollen's Reagent C H CH2CH3 HO CH2CH3
O O 3 Alkanes contain only sp hybridized carbon
C + Tollen's Reagent C + silver mirror atoms, and therefore possess only single H R HO R bonds. O A compound is only called an alkane if it contains + Tollen's Reagent no silver mirror none of the other functional groups. C produced HO R Alkenes contain at least one carbon-carbon double bond. O CH O 2 Alkynes contain at least one carbon-carbon C C + Tollen's Reagent ??? triple bond. H OH
An alkane which contains a ring made up of three CH CH or more atoms is called a cycloalkane. 2 3 CH3 H CC Likewise, a cycloalkene contains a carbon-carbon CH3 C CH3 H CCCH3 double bond somewhere in a ring of carbon atoms. H CH3 CH3 Cycloalkynes are relatively rare, for reasons we will see later (think bond angles). an alkane an alkene an alkyne We will not consider these as distinct functional groups We still classify a cycloalkene as an alkene
a cycloalkane a cycloalkene
The term aromatic has a rather detailed meaning which we will discuss next semester. Alkyl halides are compounds which have For now, when we describe a compound as containing an a halogen atom bonded to a carbon aromatic group, we mean to say that it contains a benzene ring. atom somewhere in the molecule.
We are sometimes more specific, calling a compound an alkyl chloride, alkyl Three equivalent ways of representing the benzene molecule bromide, etc.
Note that the benzene ring is not considered either an alkene or a cycloalkene; the special term aromatic makes the H H presence of the ring and double bonds understood. H C Cl H C Br As we shall see, aromatic compounds react in distinctly different ways than do alkenes, owing to delocalization of electrons within the ring. CH3 CH3
Compounds which contain the hydroxyl Thiols are similar to alcohols in group -OH bonded to carbon (R–OH) structure, with a sulfur atom replacing make up the class of compounds called the oxygen atom: R–SH alcohols. 3 Amines have a nitrogen atom bonded to Technically, the carbon should be sp hybridized. at least one carbon atom; the H OH remainder of its bonds may be to carbon or hydrogen. H3CCCH3
3 Thiols and Amines Ethers
H OH alcohols H3CCCH3 The ether functional group is described as 3 OH an sp oxygen atom bonded to two carbon atoms, and may be symbolized as R-O-R'. H SH thiols R and R' may be the same groups or H CCCH 3 3 different. SH
CH3 CH3 H N amines CH3 O C CH3 H3CCCH3 CH3 CH3CH2 O CH2CH3 O NH2 CH3
Carbonyl-Containing Functional Groups Ketones
A carbonyl group is made up of a carbon atom The ketone functional group contains a carbonyl double bonded to an oxygen atom. The carbon group, with the carbon of that group bonded to atom is not bonded to any other heteroatom. two other carbon atoms. O R and R' may or may not be the same.
the carbonyl group C R R' We will not consider the carbonyl group to be a functional group in-and-of itself; rather, it is the a ketone essential portion of two functional groups: aldehydes and ketones.
4 Aldehydes Carboxylic Acids
The aldehyde functional group contains a A carboxyl group looks similar to a carbonyl group, but at carbonyl group, with the carbon of that group least one of its sigma bonds is to a second oxygen atom. O bonded to at least one hydrogen atom. The O C C other bond is either to a carbon atom or another O OH
hydrogen atom. the carboxyl group carboxylic acid R is an alkyl group or another hydrogen atom in The carboxylic acid functional group has a hydrogen atom the case of formaldehyde. bonded to this oxygen atom. It is generally acidic, for O reasons we discussed in Chapter One.
The other bond need not be specified; it may be an alkyl C R H group, a hydrogen atom, or another –OH. an aldehyde
Carboxylic Acid Derivatives Carboxylic Acid Derivatives
There are several functional groups which are The anhydride functional group is a two-sided structurally similar to carboxylic acids. carboxyl group: O O The ester functional group has an alkyl group in
place of the hydrogen bonded to the carboxylic C C oxygen atom. O R O R'
C an anhydride R OR'
an ester R and R' may or may not be the same.
R and R' may or may not be the same.
5 Carboxylic Acid Derivatives Carboxylic Acid Derivatives
3 An amide has an sp hybridized nitrogen atom in The acid chloride (or acyl chloride) functional place of the carboxylic oxygen atom. group has a chlorine atom in place of the O carboxylic oxygen O C R N C R Cl an amide
an acid chloride The nitrogen atom is bonded to 0-2 alkyl groups.
The remaining bonds are to hydrogen.
Do not confuse amides with amines!
Circle and label all the functional groups in the molecules below. ether ketone OH CH3 OH CH3 O alcohol O
CH2 CH O C C CH2 CH O C C
CH3 CH3 Cl CH3 ester Cl CH3 aldehyde O O O O alkyl halide H H alkene
O CH3 O CH3 alkyne
C CH C CH