<p>Unit 3 Chemistry – Functional Groups in hydrocarbons [to C10]</p><p>Apart from bonding to itself or hydrogen, carbon can also form covalent bonds with other atoms or groups of atoms. These atoms or groups of atoms, that give the hydrocarbon a characteristic set of properties, are called functional groups.</p><p> functional formula found in semi-structural formula of hydrocarbon group</p><p> chloro R–Cl chloroalkanes CH 3 CH 2CH2Cl 1-chloropropane</p><p> hydroxy R–OH alkanols CH3CH2OH ethanol</p><p> carboxy R–COOH carboxylic acids CH3CH2CH2COOH butanoic acid</p><p> amino R–NH2 amines CH3CH2NH2 aminoethane</p><p> ester R–OCO–R’ esters CH3CH2COOCH3 methypropanoate</p><p> amido R–CONH–R’ amides CH3CH2CONH2 ethanamide</p><p> ether R–O–R’ ethers CH3CH2OCH2CH3 diethylether</p><p>Note: in the general formula R-OH, the R represents an alkyl group, as in </p><p>R = ethyl [CH3CH2–] in ethanol [CH3CH2OH]</p><p>Chloroalkanes  it is possible to replace a –H with a –Cl to form a chloroalkane  the name of a chloroalkane starts with “chloro” followed by the name of the alkane, with the position of the chloro is given by numbering …</p><p> eg. CH3CHClCH3 = 2-chloropropane  more than one –H can be replaced with a –Cl … </p><p> eg. CH3CH2CHClCH2CHClCH3 = 2,4-dichlorohexane  other halogens [ F, Br, I ] form similar molecules with alkanes</p><p> 2 carbon chain = ethane  2 chloro atoms on 1st carbon = 1,1-dichloroethane</p><p> 4 carbon chain = butane  chloro on 2nd carbon, methyl on 3rd carbon = 2-chloro-3-methylbutane </p><p> 4 carbon chain = butane  bromo and chloro on 2nd carbon, chloro on 3rd carbon = 2-bromo-2,3-dichlorobutane</p><p>Alkanols  in alkanols (or alcohols) with a general formula R–OH, a hydrogen on the alkane has been replaced by a hydroxy group [–OH]  hydrogen bonding due to the polar –OH group, give alkanols a higher boiling point and greater water solubility than their corresponding alkane  alkanols are named by replacing the “e” at the end of the alkane and replacing it with “ol” eg. ethane becomes ethanol  the position of the –OH in the alkane is indicated by numbering</p><p> eg. CH3CH2CHOHCH3 = butan-2-ol  more than one –H can be replaced with a –OH … </p><p> eg. HOCH2CH2OH = ethan-1,2-diol</p><p> 3 carbon chain = propane  hydroxy [–OH] group on 2nd carbon = propan-2-ol</p><p> 4 carbon chain = butane  hydroxy on 2nd carbon = butan-2-ol  2 methyl groups on 3rd carbon = 3,3-dimethylbutan-2-ol</p><p> 3 carbon chain = propane  3 hydroxy groups, on 1st, 2nd and 3rd carbon = propan-1,2,3-triol [ = glycerol ] </p><p>Carboxylic acids  carboxylic acids, with the general formula R-COOH contain the carboxy functional group [ –COOH ]  the carboxy group is always at one end of the carboxylic acid  the tendency of the carboxy group [–COOH] to donate its H+ gives these hydrocarbons their weak acidity; the polarity of the bonds in the carboxy group make smaller carboxylic acids soluble in water  to name a carboxylic acid, the number of carbons [ including the carboxy carbon ] in the longest chain has the “e” replaced by “oic acid”</p><p> eg. CH3CH2COOH = propanoic acid</p><p> 4 carbon chain = butane  carboxy group at end = butanoic acid </p><p> 6 carbon chain = hexane  carboxy group at end = hexanoic acid rd  methyl group on 3 carbon = 3-methylhexanoic acid</p><p> 5 carbon chain = pentane  carboxy group at end = pentanoic acid  ethyl group on 2nd carbon = 2-ethylpentanoic acid</p><p>Amines</p><p> amines, with the general formula R–NH2, have the amino [–NH2] functional group  the polarity of the N–H bonds in the amino group make smaller amines water soluble  the amines are named by adding “amino” to the front of the alkane name …</p><p> eg. CH3CH2CH2NH2 = aminopropane</p><p> the the position of the – NH2 in the amine is indicated by numbering …</p><p> eg. CH3CH2CHNH2CH3 = 2-aminobutane</p><p> 2 carbon chain = ethane  amino group attached = aminoethane</p><p> 5 carbon chain = pentane  amino group on 2nd carbon = 2-aminopentane</p><p>Amino acids  amino acids are the basic building blocks of proteins  amino acids contain the amine and the carboxylic acid functional groups</p><p> alanine – an -amino acid, has an –NH2 amino functional group and a –COOH carboxylic acid functional group attached to the same carbon </p><p>Functional Groups – Structure and Naming Copy each of these structural formula and then for each one:- (a) identify the group of compounds it belongs to [eg. carboxylic acid] (b) highlight and label its functional group (c) systematically name it</p><p>Remember: In these structures, if omitted, there is a carbon atom at each intersection of lines and at each free end of the line</p>