CH200 F11
Warm-up 1
CODE: _DB8976___________
Give COMPLETE answers and/or explanations to the following.
1. What is involved in naming an organic compound? Think about what you’ve read and
what the logic is. You may list a series of steps or the basic scheme as you understand
it.
First you must count the longest carbon atom chain as the parent chain; its name
becomes the root name with the ending –ane for saturated hydrocarbons. Then give
each substituent on the parent chain a name and a number. The number shows the
carbon atom of the parent chain to which the substituent is bonded. If there is only one
substituent number the parent chain from the end that gives the substituent the lower
number. If two substituent count the end that gives the lower number substituent
encountered. If there are two or more different substituent, list them in alphabetical
order and number the chain from the end that gives the lower number to the substituent
encountered first. Next alphabetize the names of the substituents first, and then insert
the prefixes. Finally, make sure to choose the parent chain with the greater number of
substituents.
2. What are some drawbacks of the way organic compounds are named?
Classification is not possible without having a full description of the individual
compounds. Chemical notation is that they are not easily described by words
and they are not easily printable. There are essentially many tedious steps
required to follow due to the very large number and variety of organic
compounds.
3. At room temperature, do you think that there is much movement occurring in an
alkane? Explain.
The gases such as methane and propane will clearly have more movement than larger
molecules such as butane and hexane. Overall, however, other than the gases alkanes
experience very little movement due to a variety of intermolecular forces.
4. There seems to be so many ways to represent the same molecule. Why? Give
examples and/or evidence for your thoughts.
Molecular formulas are very rarely used in organic chemistry, because they don’t give
any useful information about the bonding in the molecule. By using a structural
formula we can show how the various atoms are bonded. An example would be
CH2Cl2. At first you assume there’s only one way of forming CH2Cl2, but after you
draw a displayed formula you realize chlorines could be placed opposite each other or
at right angles to each other.
5. What does it mean for a molecule to be more (or less) “stable than another molecule?
The bond energy is the amount of work that must be done to pull two atoms completely apart.
Therefore, if the bond energy is greater the molecule is more stable.
6. List some way(s) to determine if one molecule is more stable than another?
CH200 F11
Warm-up 1
CODE: _DB8976___________
1). By determining the bond energy of a molecule we can find which molecule is more stable.
2). The greater the number of resonance structures the molecule has, the more stable the
molecule is.
3). Through the presence of bonds (double bond is stronger than a single bond, triple bond is
stronger than a double, and sigma bond is stronger than a pi bond.
4). Molecules having larger atoms are less stable than molecules having smaller atoms.
5). Multiplicity of bonds
6). Bond length; the longer the bond the more unstable the molecule.
7. What do you understand a conformation to be?
When an alkane has two or more carbon atoms in which the carbon can be twisted in
order to create a three-dimensional arrangement of atoms.
8. Can a conformation and a configuration be the same? Explain your answer.
The terms “conformation” and “configuration” are not interchangeable. Conformation
refers to a time variant arrangement of atoms in a particular molecule. Configuration is
a property of a particular molecule, like its boiling point or color that does not change
(unless bonds are broken).
9. How is a dihedral angle different from any other angle?
A dihedral angle is created by two intersecting planes, in which each plane is defined
by three atoms. Whereas an angle can be determined by two atoms; without necessarily
having a 3D structure.
10. What is wrong with the name cis-methylcylcohexane?
The name cis-methylcylcohexane doesn’t follow the IUPAC system. It doesn’t classify
where the substituent branches off the parent carbon chain. An example of a correct name
would be cis-1,2-dimethylcyclohexane.
11. Are anti and trans the same? If not, why?
Anti conformation is when the methyl groups are the maximum distance apart. The
prefix trans on the other hand is an indication that the substituent are on opposite sides
of the ring. Therefore, simply because substituents are on opposite sides of a carbon
chained ring, doesn’t necessarily mean that they are of maximum distance apart.