RULE 2. Name this compound as you would an alkane, but change –ane to –ene for an alkene.
This is the longest continuous chain. Select it as the parent compound. Name the parent compound octene. This chain contains 8 carbon atoms
RULE 3. Number the carbon chain of the parent compound starting with the end nearer to the double bond. Use the smaller of the two numbers on the double-bonded carbon to indicate the position of the double bond. Place this number in front of the alkene name.
IUPAC RULES This end of the chain is closest to the double bond. Begin numbering here.
IUPAC RULES The name of the parent compound is 1-octene. 8 7 4 3 2 1 6 5
RULE 4. Branched chains and other groups are treated as in naming alkanes. Name the substituent group, and designate its position on the parent chain with a number.
IUPAC RULES This is an ethyl group. 8 7 4 3 2 1 6 5 The ethyl group is attached to carbon 4. 4 4-ethyl-1-octene
Alkyl groups are electron donating toward double bond, helping to stabilize it. This donating slightly polarizes the vinylic bond, with small partial positive charge on the alkyl group and a small negative charge on the double bond carbon atom.
For example, propene has a small dipole moment of 0.35 D.
Vector sum = propene, μ = 0.33 D cis -2-butene, bp 4 o C Vector sum = 0 propene, μ = 0 trans -2-butene, bp 1 o C Vinylic bonds
- the addition of HX to an unsymmetrical alkene, the hydrogen atom attaches itself to the carbon atom (of the double bond) with the larger number of hydrogen atoms.
Step 2: Rapid reaction with a negative ion. The negative ion (Y - ) acts as nucleophile and attacks the positively charged carbon atom to give product of the addition reaction. Mechanism of electrophilic addition reactions: - C=C : electron rich part of the alkene molecule - Electrophiles: electron-seeking Step 1: Formation of carbocation. Attack of the pi bond on the electrophile to form carbocation. δ + δ -
ADDITION OF HYDROGEN HALIDES TO UNSYMMETRICAL ALKENES AND MARKOVNIKOV’S RULE
When HBr is added to an alkene in the absence of peroxides it obey Markovnikov’s rule.
When HBr (not HCl or HI) reacts with unsymmetrical alkene in the presence of peroxides (compounds containing the O-O group) or oxygen, HBr adds in the opposite direction to that predicted by Markovnikov’s rule .
The product between propene and HBr under these conditions is 1-bromopropane and not 2-bromopropane.
ANTI-MARKOVNIKOV’S RULE: FREE RADICAL ADDITION OF HYDROGEN BROMIDE
An alkene with the molecular formula C 6 H 12 is oxidised with hot KMnO 4 solution. The carboxylic acids, butanoic acid (CH 3 CH 2 CH 2 COOH) and ethanoic acid (CH 3 COOH), are produced. Identify the structural formula of the alkene.
As a fuel to power Direct-ethanol fuel cells (DEFC) in order to produce electricity.
As fuel in bipropellant rocket vehicles.
In alcoholic beverages.
An important industrial ingredient and use as a base chemical for other organic compounds include ethyl halides, ethyl esters, diethyl ether, acetic acid, ethyl amines and to a lesser extent butadiene.
Ethanol is easily miscible in water and is a good solvent. Ethanol is less polar than water and is used in perfumes, paints and tinctures.
Ethanol is also used in design and sketch art markers.
Ethanol is also found in certain kinds of deodorants.