This is BTEC level 3 Applied science unit 14 assignment - applications of organic chemistry . The assignment is written to distinction standards and I was given a DISTINCTION for this assignment in unit 14. This assignment goes through each criteria in much detail with pictures of mechanisms. I ho...
information loaded however not very helpful as a guide, I am not one to copy mas i come here for a guide to lean on and found this guide a tad poor when it came to research and acheiving the wanted information.ad
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Unit 14
Role of functional groups
In organic chemistry, a functional group refers to a group of atoms or bonds inside a substance that
are responsible for a given substances chemical reactions. A functional group behaves in the same
way and will experience similar reactions regardless of its chemical context. Additionally, functional
groups play a fundamental role in the nomenclature of organic compounds; coupling the name of
the functional group to the name of the parent alkane aids in the differentiation. Functional groups
are composed of atoms that are united and linked to one another by covalent bonds. Furthermore,
functional groups can also be classified as primary, secondary or tertiary, depending on if they are
attached to one carbon atom, two carbon atoms or none at all.
Functional groups and reactivity
organic reactions are directed and controlled by functional groups. Alkyl groups are often non-
reactive, making the site -specific reactions difficult. However unsaturated alkyl chains that have
functional groups enable higher reactivity and can be controlled more effectively. the
functionalisation of compounds, commonly referred to as a chemical synthesis, refers to the addition
of functional groups to a compound for a specific chemical reaction. By using routine synthetic
methods, organic compounds of any type can be attached to surfaces. Chemical devices can also be
functionalized by covalently linking functional molecules to the surfaces. Functional groups are used
to achieve desired surfaces in materials science. Chemical compounds with a carbonyl group (C=O),
an alcohol (-OH), a carboxylic acid (CO2H), an ester (CO2R), and an amine (NH2) are the most
common functional groups in organic chemistry.
Halogenoalkanes
Halogenoalkanes are alkanes with one or more halogen atoms replacing one or more hydrogen
atoms in their structure. Halogen alkanes are divided into three categories being: primary, secondary
and tertiary.
Primary halogenoalkane (1°C): The carbon atom is bonded to a halogen, which is also connected to
one alkyl group.
Secondary halogenoalkanes(2°C): This is made up of halogen attached to carbon. Two alkyl groups
will be directly linked to the halogen.
,Tertiary halogenoalkane (3°C): This is made up of halogen attached to carbon. Three alkyl groups
will be directly linked to the halogen.
Furthermore, halogenoalkanes can be made through two processes: a chemical reaction between
hydrogen halides and alkenes, or a physical reaction between hydrogen halides and alkenes. They
are also formed by substituting a halogen atom for an alcohol's -OH function group.
Elimination reactions of halogenoalkanes
The separation of a small group of atoms from a larger molecule is known as atom elimination. With
the addition of potassium and sodium hydroxide, as well as heat in the form of refluxing,
halogenoalkanes can carry out elimination processes. By collecting the vapours in a condenser,
refluxing allows the solution to be heated in a regulated manner, preventing the loss of reactants.
(Figure 1)
(Figure 2)
Figure 2 displays a halogenoalkane reacting with sodium hydroxide in a chemical process (NaOH). As
demonstrated, the sodium hydroxide acts as a base and removes a hydrogen ion from the carbon in
2-bromobutane. This allows for the formation of a double bond between the carbon atoms by an
electron pair.
Nucleophilic substitution of halogenoalkanes
A reaction between a positively charged electrophile and a nucleophile that results in the leaving
group being replaced by an electron-rich molecule. The halogen atom is replaced with a -OH group
to generate an alcohol in nucleophilic substitution. This is accomplished by refluxing. Heat, sodium
hydroxide, and an ethanolic solvent are required for this process.
The halogen is electronegative, which means it attracts electrons to its structure, giving it a negative
An illustration depicting nucleophilic reaction
mechanism with 2- bromobutane.
, charge. Because the carbon atom has a delta positive charge, it attracts lone pair electrons, forcing
the halogen–carbon bond to break, resulting in the formation of a bromide (Br-) ion. When 1 –
bromo-1,1-dimethylethane is refluxed with a solution of ethanol, water, and sodium hydroxide, the -
OH substitutes the halogen, resulting in an alcohol, tert-butanol.
Properties of halogenoalkanes
An illustration depicting
the boiling points of
halogenoalkanes
The boiling temperatures of halogenoalkanes rise as the chain of chloride, bromides and iodides
lengthens which is shown through the graph above. As a result of this, they will have more electrons
and hence more Vander Waal forces, necessitating more (heat) energy to break them apart, thereby
raising their boiling points.
Halogenoalkanes are mildly soluble in water because the dipole-dipole and Vander Waal forces in
the halogenoalkanes are broken apart when dissolved as well as the hydrogen bonds in the water.
There will only be dipole - dipole and Vander Waal between the molecules of water and
halogenoalkanes. Because these forces are weaker than hydrogen bonds, only a little amount of
energy is expended while separating water molecules. As a result, halogenoalkanes will be less water
soluble because they have similar intermolecular molecules forces of attraction (Vander Waal and
dipole - dipole), they are more prone to dissolve in organic solvents. Furthermore, tertiary
halogenoalkanes are more reactive in water as they have a higher polarity, while primary and
secondary are much slower.
An illustration depicting the
reactivity of halogenoalkanes
Fluoroalkanes, chloroalkanes, bromoalkenes, and iodoalkanes are listed in order of decreasing
reactivity in the bar chart above. This is due to the fact that fluorine has the highest
electronegativity, whereas the electronegativity of the carbon molecule and iodine are equal, hence
their link remains unbroken. Alkyl bromides and iodides are often heavier than water, whereas alkyl
fluorides and iodides are substantially lighter. The density of the group rises in lockstep with the size
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