Review Alkanes CnH2n+2 C4H10 butane a) ethane b) propane c) butane d) pentane CH3 (CH2) CH3 2
Review Alkanes CnH2n+2 C4H10 butane a) ethane b) propane c) butane d) pentane CH3 (CH2) CH3 2
Newman projections butane 1 2 3 4 1 staggered 2 eclipsed 3 stable 4
Nomenclature heptane heptane heptane 3 branches 2 branches 4 branches 1 2 1 3 7 3 1 3 5 7 4 6 4 2 4 6 5 2 5 6 7 heptane heptane heptane 3 branches 2 branches 4 branches
Nomenclature 3,5-diethyl -2-methyl -4-propyl heptane 2- methyl methyl 1 2 2- methyl methyl 3- ethyl 3 5 7 4 6 4- ethyl propyl propyl 5- ethyl 3,5-diethyl 3,5-diethyl -2-methyl -4-propyl heptane
Cycloalkanes linear alkanes CnH2n+2 branched alkanes cycloalkanes closed rings CnH2n cyclo propane 2 3 1 bond angle = 60o tetrahedral angle = 109o very unstable
Cycloalkanes linear alkanes CnH2n+2 branched alkanes cycloalkanes closed rings CnH2n cyclo propane 2 3 1 bond angle = 60o tetrahedral angle = 109o very unstable
Cycloalkanes cyclobutane bond angle = 88o tetrahedral angle = 109o unstable
Cycloalkanes cyclobutane bond angle = 88o tetrahedral angle = 109o unstable
Cycloalkanes cyclopentane bond angle = 108o tetrahedral angle = 109o stable
Cycloalkanes cyclopentane bond angle = 108o tetrahedral angle = 109o stable
Cycloalkanes geometric isomers cis- 1,3- dichloro cyclo butane trans- - - cis- 1,3- dichloro cyclo butane trans- 1,3- dichloro cyclo butane
Cycloalkanes cyclohexane predicted bond angle = 120o tetrahedral angle = 109o stable
Cycloalkanes cyclohexane predicted bond angle = 120o tetrahedral angle = 109o stable
cyclohexane axial positions crowded only H equatorial positions larger groups chair conformation boat conformation stable unstable
cyclohexane cis- 1,2- dimethyl cyclo hexane axial-equatorial trans- 1,2-dimethylcyclohexane trans-1,2-dimethylcyclohexane axial-axial equatorial-equatorial
Optical isomerism 3-methyl hexane bromo chloro iodo methane bromo Stereocenter 4 different substituents * * 3-methyl hexane bromo chloro iodo methane * * bromo cyclo pentane trans- 1,3-dibromo cyclopentane no C*
Alkane Summary 1. Alkanes - sp3 hybridized 2. Relatively unreactive Substitution with halogens Combustion 3. Non-polar IMF = London Dispersion Forces size structure
4. Free rotation around C-C bonds conformations 5. Non-cyclic alkanes - structural isomers 6. Cyclic alkanes - geometric isomers cis-, trans- 7. Alkanes - optical isomers stereocenters C*