Chapter 2 - Chapter 2. Alkanes Hydrocarbon and...

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Unformatted text preview: Chapter 2. Alkanes Hydrocarbon and petroleum a hydrocarbon is an organic compound consis:ng en:rely of hydrogen and carbon Crude oil Alkanes van der Waals force Van der Waals force is the aFrac:ve or repulsive force between molecules (or between parts of the same molecule) other than those due to covalent bonds or to the electrosta:c interac:on of ions with one another or with neutral molecules. Johannes Diderik van der Waals (1837 – 1923) The Nobel Prize in Physics 1910 Newman projec:on Projec:on Fisher Projec:on Sawhorse Projec:on Newman Projec:on Conforma:on of ethane (C2H6) Staggered eclipsed Conforma:on of Butane (C4H10) Gauche and an: conforma:ons FE 2.1 Organic Nomenclature CH2CH2CH3 CH3CH2CH2CHCHCH2CH2CH3 CH2CH3 1. Determine the Principal Chain 2.Number the carbons of the principal chain consecu:vely from one end to the other in the direc:on that gives the lower number to the first branching point; iden:fy the carbon number of the principal chain at which each branch occurs 3.Name each branch 4. Construct the name by wri:ng the carbon number of the principal chain at which the subs:tuent occurs, a hyphen, the name of the branch, and the name of the alkane corresponding to the principal chain 5. If the principal chain contains mul:ple subs:tuent groups, each subs:tuent receives its own number. The preflixes di, tri, tetra, and so on, are used to indicate the number of iden:cal subs:tuents 6.If subs:tuent groups occur at more than one carbon of the principal chain, alterna:ve numbering schemes are compared number by number, and the one is chosen that gives the smaller number at the first point of difference; Subs:tuent groups are cited in alphabe:cal order in the name regardless of their loca:on in the principal chain (the numerical prefixes di, tri, and so on, as well as the hyphenated prefixes tert ­ and sec ­ are ignored in alphabe:zing, but the prefixes iso, neo, and cyclo are considered in the alphabe:zing subs:tuent groups) 7. If the numbering of different groups is not resolved by the other rules, the first ­cited group receives the lowest number Organic Nomenclature CH2CH2CH3 CH3CH2CH2CHCHCH2CH2CH3 CH2CH3 4 ­ethyl ­5 ­propyloctane Cons:tu:onal Isomerism (structural isomerism) Connec:vity (study problem 2.2) Pentane Isopentane Neopentane Configura:onal and conforma:onal isomers Configura:onal Isomer Conforma:onal isomer Carbon Subs:tu:on Nomenclature of cycloalkanes (CnH2n) Cyclohexane (C6H12) Skeletal structure Physical proper:es of alkanes Boiling points and mel:ng points of alkanes What are b.p. and m.p.? Compare the b.p. and m. p. of neopentane and normal pentane: Solubility and density Combus:on Page 76 12.5 Occurrence and use of alkanes Crude oil Func:onal groups “R” Nota:on Alkyl subs:tuents Aryl subs:tuents Key Points •  •  •  •  •  •  •  •  •  •  •  Hydrocarbon (alipha:c and aroma:c) Alkanes, alkenes, alkynes Names of the first 12 unbranched alkanes Newman projec:on Conforma:on of ethane (staggered, eclipsed) and butane (an:, gauche) Nomenclature of open ­chain and cyclo ­alkanes Cons:tu:onal isomer Trends of physical proper:es in alkanes Frac:onal dis:lla:on Func:onal groups (alkyl and aryl) “R” nota:on ...
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This note was uploaded on 08/24/2010 for the course CHEM 3351 taught by Professor Ellison during the Fall '07 term at Colorado.

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