a) The F-F bond dissociation energy (BDE) is approximately 37 kcal/mol. For reference, a “normal” C-C or C-H bond has a BDE of approximately 100 kcal/mol. Briefly explain why the F-F bond is much weaker than a C-C or C- H bond b) Consider the balanced equation below, where “Ph” indicates a monosubstituted benzene (“phenyl”) ring: Ph-H + F-F -> Ph-F + H-F The BDEs of the molecules
Classes Of Functional Groups
Organic Chemistry deals mostly with carbon and hydrogens, also called hydrocarbons, but those groups which replace hydrogen and bonds with carbon to give a characteristic nature, unique of their own, to the hydrocarbon they are attached to, are called functional groups. All the compounds belonging to a functional group undergo reactions in a similar pattern and are known to have similar physical and chemical properties.
Characteristics Of Functional Groups
In organic chemistry, we encounter a number of special substituent groups which are attached to the hydrocarbon backbone. These groups impart certain characteristics to the molecule of which it is a part of and thus, become the highlight of that particular molecule.
IUPAC Nomenclature
In Chemistry, IUPAC stands for International Union of Pure and Applied Chemistry which suggested a systematic naming approach for the organic and inorganic compounds, as in the beginning stage of nomenclature one single chemical compound was named in many ways by which lead to confusion. The need for this approach aroused as the number of chemical compounds newly discovered were increasing (approximately 32 million compounds) and the basic concept of nomenclature i.e. the trivial nomenclature and the derived system of nomenclature failed to overcome the challenge. It is an important task to name a chemical compound systematically and unambiguously which reduces lots of confusion about the newly reported compounds.
a) The F-F
For reference, a “normal” C-C or C-H bond has a BDE of approximately 100
kcal/mol. Briefly explain why the F-F bond is much weaker than a C-C or C-
H bond
b) Consider the balanced equation below, where “Ph” indicates a
monosubstituted benzene (“phenyl”) ring:
Ph-H + F-F -> Ph-F + H-F
The BDEs of the molecules involved, in kcal/mol, are as follows:
Bond BDE (kcal/mol)
Ph-H 112
Ph-F 116
H-F 136
What is the delta H for the fluorination of benzene by F2? Is the reaction favored or not?
c) Why is the fluorination of benzene with F2 rarely done? For reference, the
bromination of benzene with Br2 has a delta H of approximately -12 kcal/mol.
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