Lesson 4: Unsaturated Hydrocarbons - Alkenes & Alkynes

unsaturated hydrocarbon

hydrocarbon in which one or more carbon-carbon multiple bonds (double bonds, triple bonds or both) are present.

unsaturated hydrocarbon

they have physical properties same with the saturated hydrocarbons but their chemical properties are different.

unsaturated hydrocarbon

They are chemically more reactive compare with their saturated counterparts.

presence of multiple bonds

serve as location where chemical reactions can happen

functional group

Wherever a specific portion of a molecule governs its chemical properties, that portion of the molecule is called _____

functional group

this is where most of unsaturated hydrocarbon chemical reactions occur

carbon-carbon multiple bonds

the functional group of an unsaturated hydrocarbon.

acyclic

an open chain structure

alkene

an acyclic unsaturated hydrocarbon that contains one or more carbon-carbon double bonds.

CnH2n

general formula of alkene

ene

this suffix indicates the presence of pi bond or the double bond

dehydrohalogenation of alkyl halide

involves the loss of a hydrogen and a halide from an alkyl halide (RX).

dehydrohalogenation

normally accomplished by reacting the alkyl halide with a strong base, such as potassium hydroxide producing an alkene.

R-X + KOH > CnH2n + KX + HOH

general formula of dehydrohalogenation

alkane

this is formed when adding hydrogen to an alkene in the presence of a catalyst

addition of hydrogen

adding hydrogen to an alkene in the presence of a catalyst will form an alkane. Since there is the presence of pi bond (or the double bond) in an alkene, they are potentially more reactive

addition of halogen

a simple organic reaction where

a halogen molecule is added to the carbon–carbon double bond of an alkene functional group.

alkynes

represent the second class of unsaturated hydrocarbons.

alkynes

an acyclic unsaturated hydrocarbon that contain one or more carbon-carbon triple bonds.

alkyne

it has four fewer hydrogens than the corresponding alkane.

CnH2n-2

general formula for alkyne with one triple bond

C2H2

simplest member of this type of alkyne has the molecular formula of ____

acetylene

common name for the smallest alkyne.

alkenynes

hydrocarbons in which both the double and the triple bonds are present.

C=C group

the alkene functional group

parent chain

it is identified in IUPAC name and this must include the two carbons with the pi bond.

pi bond

kapag hinahanap yung lowest number sa pagne-name ng alkenes, ito yung priority instead of the location ng substituents

sym

prefix used when the two groups bonded to the pi electron system/ double bond functional group is symmetrically situated

unsym

prefix used when the two groups bonded to the pi electron system/ double bond functional group is asymmetrically situated

ethylene

common name of CH2=CH2

alkadiene

group of open chain hydrocarbon with two double bonds

allene

common name of two double bonds in the same carbon: C=C=C

vinyl group

name of this group:

-CH=CH2

allyl group

name of this group:

-CH₂-CH=CH₂

divinyl

common name of this:

CH₂=CH-CH=CH₂

diallyl

common name of this:

CH₂=CH-CH₂-CH₂-CH=CH₂

dehydration of alcohols

the reaction of alcohols to generate alkene proceeds by heating the alcohols in the presence of a strong acid, such as sulfuric or phosphoric acid, at high temperatures.

sulfuric acid

The common acid used in the dehydration of alcohols which serves as the dehydrating agent.

alkene and water

products in dehydration of alcohols

dehydrohalogenation of alkyl halide and dehydration of alcohols

two preparation of alkenes

CnH2n + X2 > X-CH2-CH2-X

general formula of addition of halogens

addition of hydrogen and addition of halogen

two reactions of alkenes

terminal alkyne

If the triple bond is at the end of the chain, the alkyne is classified as a _____

acetylene

two carbons bonded with a triple bond

double bond

it has priority over a triple bond in numbering the chain, that is, when numbering systems are equivalent.