Chapter 4 Alkanes and cycloalkanes Conformations of molecules(分子 的构象
Chapter 4 Alkanes and cycloalkanes: Conformations of Molecules (分子 的构象）
4.1 Introduction of alkanes and cycloalkanes General formula chonno for alkanes C3Ha CH3CH2CH3 Propane General formula C,H2n for cycloalkanes( 烷烃) CH n2n Cyclopropane
4.1 Introduction of alkanes and cycloalkanes • General formula CnH2n+2 for alkanes • C3H8 CH3CH2CH3 Propane • General formula CnH2n for cycloalkanes (环 烷烃） • CnH2n Cyclopropane
Sources of alkanes ·4.1 A Petro|eum 4.1B Petroleum refining Table 4.1 Typical fractions obtained by distillation of petroleum Mixtures of alkanes, fortunately, are perfectly suitable for uses as fuels, solvents and lubricants, the primary uses of petroleum
Sources of alkanes • 4.1A Petroleum • 4.1B Petroleum refining • Table 4.1 Typical fractions obtained by distillation of petroleum • Mixtures of alkanes, fortunately, are perfectly suitable for uses as fuels, solvents, and lubricants, the primary uses of petroleum
41 C Cracking(裂解) When a mixture of alkanes from the gas oil C12 and higher) fraction is heated at very high temperatures(--500oC)in the presence of a variety of catalysts, the, the molecules break apart and rearrange to smaller, more highly branched alkanes containing 5-10 carbon atoms. This process is called catalytic cracking(催化裂解). Cracking can also be done in the absence of a catalyst- called thermal cracking(热裂解)
4.1 C Cracking (裂解） When a mixture of alkanes from the gas oil (C12 and higher) fraction is heated at very high temperatures (--500 oC) in the presence of a variety of catalysts, the, the molecules break apart and rearrange to smaller, more highly branched alkanes containing 5-10 carbon atoms. This process is called catalytic cracking (催化裂解）. Cracking can also be done in the absence of a catalyst--- called thermal cracking (热裂解）
2, 2, 4-trimethylpentane ( octane异辛烷) CH3 CH3 H3C—c—CH2-CH—CH3 CH3 Isooctane burns very smoothly without knocking, but heptane Burns to produce much knocking. A mixture of 87% isooctane and 13% heptane would be rated as 87-octane gasoline
2,2,4-trimethylpentane (isooctane 异辛烷) H3C C CH3 CH3 CH2 CH CH3 CH3 Isooctane burns very smoothly without knocking, but heptane Burns to produce much knocking. A mixture of 87% isooctane and 13% heptane would be rated as 87-octane gasoline
4.2 Shapes of alkanes The tetrahedral carbon atoms their chains are zigzagged(锯齿形) and not at all straight chains (E 链) Unbranched chain alkanes(直链烷烃) Branched chain alkanes(支链烷烃)
4.2 Shapes of alkanes The tetrahedral carbon atoms their chains are zigzagged (锯齿形） and not at all straight chains （直 链） Unbranched chain alkanes (直链烷烃） Branched chain alkanes (支链烷烃）
Primary, secondary and tertiary carbon atoms and hydrogen(伯,仲,叔碳原子 和氢原子 Quaternary carbon(季碳)(4°C CH3 CH H3C—C—CH2-CH—CH3 Tertiary carbon(叔碳)(3Cand3H) CH3 Isooctane Secondary carbon(仲碳)(2°Cand2°H Primary carbon(伯碳) and primary hydrogen(伯氢)(1°Cand1H)
Primary, secondary and tertiary carbon atoms and hydrogen (伯，仲， 叔碳原子 和氢原子） H3C C CH3 CH3 CH2 CH CH3 CH3 Isooctane Primary carbon （伯碳）and primary hydrogen (伯 氢 ） (1 o C and 1 o H) Quaternary carbon (季 碳 ） (4 o C) Secondary carbon （仲碳) (2 o C and 2 o H ) Tertiary carbon （叔碳）(3 o C and 3 o H)
How to write constitutional somers?(怎样写构形异构 体 CH3CHLCHCH, CH3 n-pentane Pentane CHCHCHoCH Isopentane 2-methylbutane CHCH H3C CH3 Neopentane 2, 2-dimethylpropane CHa
How to write constitutional isomers ? (怎样写构形异构 体 ?） CH3 CH2 CH2 CH2 CH3 n-pentane CH3 CHCH2 CH3 CH3 Isopentane H3 C CH3 CH3 CH3 Neopentane 2-methylbutane 2,2-dimethylpropane Pentane
Problem 4.2 Write the following constitutional isomers a C7H16(alkanes) b. CaH 7H14(alkenes and cycloalkanes c C5H12o(alcohol and ethers d. CsHj00(aldehydes and ketones)
Problem 4.2 Write the following constitutional isomers. a. C7 H16 (alkanes) b. C7 H14 (alkenes and cycloalkanes) c. C5 H12 O (alcohol and ethers) d. C5 H10 O (aldehydes and ketones)
43 UPAC nomenclature IUPAC nomenclature of alkanes IUPAC nomenclature of alkyl halides UPac nomenclature of alcohols
4.3 IUPAC nomenclature • IUPAC nomenclature of alkanes • IUPAC nomenclature of alkyl halides • IUPAC nomenclature of alcohols