Alkenes, Alkynes and aromatic compounds Hydrocarbons (contain only carbon and hydrogen) a) Saturated: (Contain only single bonds) Alkanes (C n H 2N + 2 ) Cycloalkanes (C n H 2N ) b) Unsaturated: contain Alkenes: double bonds (,,,C n H 2N ) Alkynes: triple bonds ((C n H 2N - 2 ) Aromatic: benzene like compounds 1
32
Embed
Alkenes, Alkynes and aromatic compounds Hydrocarbons (contain only carbon and hydrogen) a)Saturated: (Contain only single bonds) Alkanes (C n H 2N + 2.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Classification according to the position of double bonds
Cis-Trans (Z-E) Isomerism in Alkenes
Because rotation at carbon–carbon double bonds is restricted, cis–trans isomerism (geometric isomerism) is possible.If the two groups are identical we distinguish the two isomers by adding the prefix cis (same side) or trans (opposite sides)
Example
10
11
If the groups attached to the double bond are different, we distinguish the two isomers by adding the prefix Z (same side) or E (opposite sides) depending on the atomic number of the atoms attached to each end of the double bond
The most common reaction of alkenes is addition of a reagent to the carbons of the double bond to give a product with a C-C single bond.
What is the difference between addition and substitution reactions?
Substitution :
Addition:
14
Example for reaction a:
15
16
Example 1 for reaction b :
17
When an unsymmetric reagent adds to an unsymmetric alkene, the electropositive part of the reagent bonds to the carbon of the double bond that has the greater number of hydrogen atoms attached to it
Example 2 for reaction b:
18
Example for reaction c:
19
c.
Example for reaction C:
20
A polymer is a large molecule, usually with a high molecular weight, built up from small repeating units. The simple molecule from which these repeating units are derived is called a monomer, and the process of converting a monomer to a polymer is called polymerization.
d.
Reactions of Alkynes
21
22
23
Examples to reactions a:
24
Aromatic Compounds
Benzene, C6H6, is the parent hydrocarbon of the especially stable compounds known as aromatic compounds .
25
Nomenclature of Aromatic Compounds
26
Pre
serv
ati
ve f
or
uri
ne
sp
eci
men
s
Nomenclature of Aromatic CompoundsWhen two
substituents are present, three isomeric structures are possible. They are designated by the prefixes ortho- , meta-, and para, which are usually abbreviated as o- , m-, and p- , respectively.
27
28
Examples :
29
Examples :
30
The most common reactions of aromatic compounds involve substitution of other
atoms or groups for a ring hydrogen on the aromatic unit. Here are some typical
substitution reactions of benzene.
Reactions of aromatic compounds
Polycyclic Aromatic Hydrocarbons
Naphthalene is a planar molecule with two fused benzene rings. The two rings share two carbon atoms.
Phenanthrene is an isomer of anthracene and is considered to be the basic structure of many important compounds like cholesterol, male and female sex hormones, and Vitamin D.
31
Some polycyclic aromatic compounds such as benzo[a]pyrene are cancerogenic
Cancerogenic compounds can produce a tumor on mice in a short time when only trace amounts are painted on the skin.
These carcinogenic hydrocarbons are present not only in coal tar but also in tobacco smoke and can be formed in barbecuing meat