24.2 Alkanes Alkanes have the general formula C n H 2n+2 where n = 1,2,3,… only single covalent bonds saturated hydrocarbons because they contain the maximum number of hydrogen atoms that can bond with the number of carbon atoms in the molecule CH 4 C2H6C2H6 C3H8C3H8 methaneethanepropane
24.2 Alkane Nomenclature 1.The parent name of the hydrocarbon is that given to the longest continuous chain of carbon atoms in the molecule. CH 3 CH 2 CHCH 2 CH 3 1234567 4-methylheptane 2.An alkane less one hydrogen atom is an alkyl group. CH 4 CH 3 methane methyl
24.2 Alkane Nomenclature 3.When one or more hydrogen atoms are replaced by other groups, the name of the compound must indicate the locations of carbon atoms where replacements are made. Number in the direction that gives the smaller numbers for the locations of the branches. CH 3 CHCH 2 CH 3 12345 2-methylpentane CH 3 CH 2 CHCH 3 12345 4-methylpentane
24.2 Alkane Nomenclature 4.Use prefixes di-, tri-, tetra-, when there is more than one alkyl branch of the same kind. CH 3 CH CH 2 CH 3 123456 2,3-dimethylhexane CH 3 CHCCH 2 CH 3 12 3 456 3,3-dimethylhexane
24.2 Structural isomers are molecules that have the same molecular formula but different structures name:
How many structural isomers does pentane, C 5 H 12, have? CCCC C HHHHH H HHHHH H CCC C HCH 3 HH H HHHH H CC C H H H HH H name: 24.2 name:
24.2 Alkane Nomenclature 5.Use previous rules for other types of substituents. CH 3 CH CH 3 Br 1234 NO 2 2-bromo-3-nitrobutane CH 2 CHCH 3 Br 1234 NO 2 1-bromo-3-nitrobutane
What is the IUPAC name of the following compound? 24.2 1234567 8 CH 3 CHCH 2 CHCH 2 CH 3 C2H5C2H5 CH 2 CH 3 What is the structure of 2-methyl-3-propylhexane?
Note about Substituents The presence of substituents containing elements other than C and H leads to other groups… halogenoalkanes – contain halogens –F = fluoro –Cl = chloro –Br = bromo –I = iodo
What is the IUPAC name of the following compound? 24.2 1234567 CH 3 CHCH 2 CHCH 2 Cl CH 3 I What is the structure of 2-bromo-3-ethylhexane?
24.2 Cycloalkanes Alkanes whose carbon atoms are joined in rings are called cycloalkanes. They have the general formula C n H 2n where n = 3,4,…
What is the IUPAC name of the following compound? 24.2 What is the structure of 1,2-dibromocyclohexane? CH 3 Cl
24.2 Alkenes Alkenes have the general formula C n H 2n where n = 2,3,… contain at least one carbon-carbon double bond also called olefins CH 2 CHCH 2 CH 3 1-butene or but-1-ene CH 3 CH CH 3 name: CC Cl HH CC H H cis-dichloroethene trans-dichloroethene name:
24.2 Alkynes Alkynes have the general formula C n H 2n-2 where n = 2,3,4,… contain at least one carbon-carbon triple bond 1-butyne or but-1-yne2-butyne or but-2-yne CH CCH 2 CH 3 CC Draw a molecule of acetylene – more properly called ethyne: Why isn’t there a “1” in ethyne?
24.3 Aromatic Hydrocarbons C C C CC C H H H H H H C C C CC C H H H H H H benzene
24.3 Aromatic Hydrocarbons If benzene is a substituent, it is called ‘phenyl’…. Go figure… CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 name: name: phenyl salicylate (common) or phenyl–2-hydroxybenzoate If benzene has a –CH 2 attached to it… and is a substituent, it is called ‘benzyl’…. Odd….
24.4 Functional Group Chemistry Alcohols contain the hydroxyl functional group and have the general formula R-OH. propan-2-ol 1,2-ethanediol or ethan-1,2-diol1-hydroxybenzene
24.4 Functional Group Chemistry Ethers have the general formula R-O-R’. Their names are a bit trickier… and IB doesn’t expect you to name them… but just in case you are interested… CH 3 OCH 3 is called methyl methyl ether or dimethyl ether or methoxy methane
24.4 Functional Group Chemistry Aldehydes and ketones contain the carbonyl ( ) functional group. O C R C H O aldehydes have the general formulaR C R’ O ketones have the general formulaH C H O H C O CH 3 C O H3CH3C methanal (formaldehyde) ethanal (acetaldehyde) propanone (acetone) What is the difference?
24.4 Functional Group Chemistry Draw 3-chloropentanoic acid:
24.4 Functional Group Chemistry Esters have the general formula R’COOR, where R is a hydrocarbon group. CH 3 COOH + HOCH 2 CH 3 CH 3 C O CH 2 CH 3 + H 2 O O ethyl ethanoate (ethyl acetate) CH 3 CH 2 C O CH 3 O name:
24.4 Functional Group Chemistry Draw propyl butanoate:
24.4 Functional Group Chemistry Amines are organic bases with the general formula R 3 N. CH 3 NH 2 + H 2 O RNH 3 + + OH - CH 3 CH 2 NH 2 + HCl CH 3 CH 2 NH 3 + Cl - methylamine name:
24.4 Functional Group Chemistry Amides have the general formula R’CONH 2, where R is a hydrocarbon group. CH 3 C NH 2 O ethanamide CH 3 CH 2 C NH 2 O name:
24.4 Functional Group Chemistry Nitriles have the general formula RCN, where R is a hydrocarbon group. ethanenitrile or cyanomethane CH 3 C N