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butane. Review. Alkanes. C n H 2n+2. C 4 H 10. a) ethane b) propane c) butane d) pentane. CH 3. (CH 2 ). CH 3. 2. Newman projections. butane. 1. 2. 3. 4. 1. 2. 3. 4. staggered. eclipsed. stable. Nomenclature. 1. 2. 1. 3. 7. 3. 1. 3. 5. 7. 4. 6. 4. 2. 4.
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butane Review Alkanes CnH2n+2 C4H10 a) ethane b) propane c) butane d) pentane CH3 (CH2) CH3 2
Newman projections butane 1 2 3 4 1 2 3 4 staggered eclipsed stable
Nomenclature 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 2 branches 4 branches branches
Nomenclature 1 2 2- methyl methyl 3- ethyl 3 5 7 4 6 ethyl 4- 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 2 3 cyclo propane 1 bond angle = 60o tetrahedral angle = 109o very unstable
Cycloalkanes cyclobutane bond angle = 88o tetrahedral angle = 109o unstable
Cycloalkanes cyclopentane bond angle = 108o tetrahedral angle = 109o stable
geometricisomers Cycloalkanes - - trans- 1,3- dichloro cyclo butane cis- 1,3- dichloro cyclo butane
Cycloalkanes cyclohexane predicted bond angle = 120o tetrahedral angle = 109o stable
cyclohexane axial positions crowded onlyH equatorial positions larger groups boat conformation chair conformation stable unstable
cyclohexane cis- 1,2- dimethyl cyclo hexane cis-1,2-dimethylcyclohexane axial-equatorial trans- 1,2-dimethylcyclohexane trans-1,2-dimethylcyclohexane axial-axial equatorial-equatorial
Optical isomerism Stereocenter 4 different substituents C*= * * 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*