Organic Chemstry

1. Alcohols and Esters
What is alcohols?
The alcohols are a homologous series of compounds that contain –OH as the functional group. A
functional group af atoms in a structure that determines the characteristic reaction of compound.
The name all alcohols have the sam ending (-ol). The general formula of the alcohols is CnH2n+1OH,
and they can be referred to as the alkanols.
Who is discovered alcohols?
Alcohols discovered by a chemist name Abu Bakr Muhammad ibn Zakariya al-Razi.
How to make alcohols?
Alcohols can produce by hydration of ethene. The ethene reacted with water (steam) on conditions
300o
C and 60 atmosphere using phosphoric acid as catalyst. It will produce alcohols. There is other
methode to make alcohols, it is fermentation. Fermentation is an aerobic process. It takes place
under conditions where there is no air or oxygen available. At the fermentation reaction, glucose will
be change into ethanol and carbon dioxide by yeast and enzymes.
What is the properties of alcohols?
Table 1. Homologous of alcohols
Alcohol
Molecular Formula
(CnH2n+1OH)
Boiling
point/o
C
Methanol CH3OH 65
Ethanol CH3CH2OH 78
Propan-1-ol CH3CH2CH2OH 97
Butan-1-ol CH3 CH2 CH2CH2OH 117
Pentan-1-ol CH3 CH2 CH2 CH2 CH2OH 137
Table 2. Homologous of alkane
Alkane Molecular Formula (CnH2n+2)
Boiling
point/o
C
Methane CH4 -164
Ethane CH3CH3 -87
Propane CH3CH2CH3 -42
Butane CH3 CH2 CH2CH3 0
Pentane CH3 CH2 CH2 CH2 CH3 +36
The table 1 above show the molecular formulae of the early member of the alcohols series.
The boiling points of the alcohols increase as the number of carbon atoms increases. The melting
point also increase as the number of carbon atoms increases. From the table 1 an table 2, it
compared that the boiling point of an alcohol is always much higher than that of the alkane with the
same number of carbon atoms. It is because alcohols have intermolecular forces. The intermolecular
forces are including van der Waals dispersion forces and hydrogen bonds. In alkanes, the only
intermolecular forces are van der Waals dispersion forces. Hydrogen bonds are much stronger than
these and therefore it takes more energy to separate alcohol molecules than it does to separate
alkane molecules.
boling point
increasing
boling point
increasing

2. The small alcohols are completely soluble in water. Whatever proportions will mix them in, a
single solution will get. However, solubility falls as the length of the hydrocarbon chain in the alcohol
increases. Once we get to four carbons and beyond, the fall in solubility is noticeable, and we may
well end up with two layers in our test tube.
How many kinds of alcohol?
Alcohols fall into different classes depending on how the -OH group is positioned on the
chain of carbon atoms.
1. Primary alcohols. In a primary (1°) alcohol, the carbon which carries the -OH group is only
attached to one alkyl group
2. Secondary alcohols. In a secondary (2°) alcohol, the carbon with the -OH group attached is
joined directly to two alkyl groups, which may be the same or different.
3. Tertiary alcohols. In a tertiary (3°) alcohol, the carbon atom holding the -OH group is attached
directly to three alkyl groups, which may be any combination of same or different.
What is the uses of alcohol?
Many everyday items use alcohols. Alcohols can use as a fuel, it because the alcohols can reacted
with oxygen to produce energy, it is called as combution. Combution also produce carbon dioxide
and water. Alcohols can also use as material to make other compound, for example to make ester by
esterification process.
What is the esters? and How to make esters?
Esters are compound derived from carboxylic acid. A carboxylic acid contains COOH group, and in an
esters, the hydrogen in this group is replaced by a hydrocarbon group such as alkyl group like
methyl, ethyl, or propyl. Esters are produce by esterification process, it is reaction between alcohol
and carboxylic acid then produce ester and water. The esterification process take place in acid
condition, so the rection used sulfuric acid also.
What is the properties of esters?
The boiling point and melting point of esters are increases as the number of carbon atoms increases,
it is same with the alcohols properties. But, in same number of carbon atoms, the alcohols has
higher boiling point and melting point than the esters, it is because alcohols have many
intermolecular forces than the esters. None of the esters are water soluble, it because the chain
lenghts are so great and too many hydrogen bonds between water molecules would have to broken,
so ester insoluble in water. This properties of esters are different with alcohols, small alcohols are
soluble in water.
What is the uses of esters?
Esters can be use as foods flavouring, perfumes because it have pleasant smells. The compound of
ester that use as flavouring are ethyl 2-methylbutanoate as apple smell or flavour, butyl butanoate
as smell or flavour pineapple, octyl ethanoatae as smell or flavour orange, and other. Ester can also
use as material to make polymers such as terylene, and as material to make soap.