Ankan 1.ppt

HOÁ HỌC HỮU CƠ
Organic Chemistry
CHƯƠNG 6
Alkanes
GIỚI THIỆU MÔN HỌC

: HOÙA HOÏC HÖÕU CÔ
(ORGANIC CHEMISTRY)
Soá tín chæ: 3 (3.1.6)
Maõ soá moân hoïc: 606010
Noäi dung toùm taét moân hoïc:
Lieân keát- Caáu taïo-caáu truùc hôïp chaát höõu cô
Phaûn öùng vaø cô cheá phaûn öùng höõu cô
Caùc phöông phaùp cô baûn toång hôïp caùc hôïp chaát höõu cô
Tính chaát lyù hoùa caùc hôïp chaát höõu cô
ÖÙng duïng: Hôïp chaát maøu, hôùp chaát coù höông, chaát hoaït ñoäng beà maët, chaát noå, chaát dieät khuaån-coân truøng, chaát kích thích taêng tröôûng….
Unbranched Alkanes
“Straight-chain” alkanes have a zig-zag orientation when they are in their most straight orientation

Branched Alkanes
Branched alkanes have at least one carbon which is attached to more than two other carbons

Physical Properties
Boiling points of unbranched alkanes increase smoothly with number of carbons
CH4-C4H10: gazes
Melting points roughly increase with number of carbons
C5H12-C17H36: liquids

Low polarity
Insoluble in water
Soluble in non-polar solvents
Physical Properties
The boiling point increases with the length of the chain
Structural Isomers
Constitutional isomers have the same molecular formula but different connectivity of atoms
IUPAC Rules for Alkanes and Alkyl Halides
Select the longest continuous chain
Basic name
Number the carbons form the end nearest the first branch
Numbering
Locate substituents on the main chain
Location
If two substituents on the same carbon, use the number twice
Identify substituents
Identification
if more than one use “di”, “tri”, “tetra”,…
Put substituents in alphabetical order
Separate numbers from letters using dashes and place the basic name at the end.
DANH PHÁP
http://www.acdlabs.com/iupac/nomenclature/
Radicals
CH3- methyl (Me)
CH3-CH2- ethyl (Et)
CH3-CH2-CH2- n-propyl (nPr)
(CH3)2-CH- iso-propyl (iPr)
CH3-CH2-CH2-CH2- n-butyl (nBu)
(CH3)2-CH-CH2- iso-butyl (iBu)
(CH3)3-C- tert-butyl (tBu)
C6H5- phenyl (Ph)

DANH PHÁP
DANH PHÁP
Alkanes
DANH PHÁP
DANH PHÁP
LAI HOÁ sp3
Nobel prize 1969
Sir Derek Barton (UK, 1918-1998)
Odd Hassel (Norway, 1897-1981)
for their contributions to the development of the concept of conformation and its application in chemistry"
Sir Derek Barton
Nobel Lecture starting with this citation:


Stereoisomers
Conformers
Isomers resulting from the free rotation of a single bond
Ethane: staggered conformation (C-H bonds on adjacent carbons as far apart from each other as possible)
The drawing to the right is called a Newman projection




eclipsed conformation: all C-H bonds on adjacent carbons directly on top of each other
The Newman Representation
The Newman Representation
Staggered and eclipsed
Staggered
Eclipsed
3D Formulas
The Torsional Strains
Staggered: most stable
Eclipsed: least stable
Ethane conformation
the staggered conformation is more stable than eclipsed by 12 kJ mol-1

ĐỒNG PHÂN CẤU DẠNG
ĐỒNG PHÂN CẤU DẠNG
Butane
Anti most stable




Fully eclipsed most unstable
Butane
Gauche less stable than anti





Eclipsed less unstable than fully eclipsed
Butane
Butane
ĐỒNG PHÂN CẤU DẠNG
ĐỒNG PHÂN CẤU DẠNG
Preparation of Alkanes
Catalytic hydrogenation of alkenes and alkynes
Preparation of Alkanes
Preparation of Alkanes
Preparation of Alkanes
Preparation of Alkanes
The Kolbe reaction is the electrosynthesis of hydrocarbons via electrooxidation of carboxylic acids.

Preparation of Alkanes
Preparation of Alkanes
Reduction/Oxidation
Reduction: gain of hydrogen, loss of oxygen, …
Level of oxidation decreases
Oxidation: gain of oxygen, loss of hydrogen, …
Level of oxidation increases
Hydrogenation: reduction of alkenes and alkynes
Syn Addition in Heterogeneous Catalysis
hydrogen and alkene adsorbed to the catalyst surface
Syn Addition
Both hydrogens add to the same face of the alkene (syn addition)

Examples
1,2-dimethylcyclohexene
Reduction of Alkyl Halides
With metals
Paul Sabatier (1854-1941)
Nobel Prize 1912
"for his method of hydrogenating organic compounds in the presence of finely disintegrated metals whereby the progress of organic chemistry has been greatly advanced in recent years"
University of Toulouse, France
Victor Grignard
Nobel prize 1912
"for the discovery of the so-called Grignard reagent, which in recent years has greatly advanced the progress of organic chemistry"
University of Nancy, France

Ph. Barbier, University of Lyon, France
Barbier reaction
Grignard Reagents
Grignard reagent preparation
Reaction of organic halides with magnesium turnings in ether (DRY ether)




Killed with water: form alkanes
Grignard Reagents
Strongly react with water
Grignard reagents behave as if they were carbanions and they are therefore very strong bases
R rich in electron
Grignard Reagents
Formally: conversion of halides to hydrogen

The Grignard reaction: addition of Grignard reagents to carbonyls
Elias J. Corey
Nobel Prize 1990
"for his development of the theory and methodology of organic synthesis"
Harvard University, USA

Many Corey reactions…
(Corey-Winter, Corey-Chakovsky, Corey-Bakshi-Shibata, Corey-Fuchs, Corey-Kim, …)

… and reagents
PDC, PCC, …
Organometallics
Organolithium reagents



Organocuprate reagents (Gilman reagents)
Corey-Posner, Whitesides-House
Coupling of two alkyl halides Organocuprate reagents
Henry Gilman
Henry Gilman (1893-1986), Iowa State University
Talking about his research as a student: `A sheer delight. Here I was, just a senior. We`d work at night until 11 or 12 o`clock, without any compulsion--just for the joy of it.`
Post doc at Harvard with Kohler who is credited with having introduced the use of the Grignard reagent to the U.S.A.
Lithium dialkylcuprate are called Gilman Reagents

Posner, Whitesides and House
Georges M. Whitesides, Harvard University
Material Science
Gary H. Posner, Johns Hopkins University
Organic Chemistry
H O. House, Georgia Institute of technology


Examples