Organic h/w KEY

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Warm up
1. What is the difference between ionic and covalent bonds?
Ionic- transfer electrons Covlaent- share electrons
2. What type of bonding occurs: (A) in Carbon compounds?
covalent
(B) between compounds?
Vanderwaals forces
3. What are valence electrons? electrons in highest occupied energy level
Hydrocarbons
Less than 200 years ago it was thought Carbon compounds found in nature could
be synthesized only by living organisms. From the word organism came the
classification of these carbon compounds as organic.
Today organic chemistry includes chemistry of virtually all carbon compounds,
regardless of their origin.
Hydrocarbons: contain only C & H
Because a carbon atom contains four valence electrons, it always forms 4 covalent
bonds.
Ex. Methane
H

H-C-H

H
line represents shared electrons.
VSEPR shape: tetrahedral
Alkanes: Simplest hydrocarbons. All carbon-carbon bonds are single covalent
bonds and all other bonds are carbon-hydrogen bonds.
# Carbons
1
Name
Methane
Molecular Formula
CH4
2
Ethane
C2 H 6
3
Propane
4
Butane
CH3-CH3
C3H8
C4H10
Structural Formula
CH3CH2CH3
CH3(CH2)2CH3
Practice:
1. Draw complete structural formula
for pentane.
C-C-C-C-C-
2. Draw a condensed structural formula
for hexane.
CH3(CH2)4CH3
Branched – Chain Alkanes:
Longest continuous carbon chain of a branched-chain hydrocarbon is the parent
alkane. All other carbon atoms or groups of carbon atoms are regarded as
substituents called alkyl groups.
Alkyl groups named by removing ane and adding –yl.
Ex: methyl (CH3-)
ethyl (CH3CH2-) propyl (CH3CH2CH2-)
7
6 5
4
3 2 1
CH3-CH2-CH2-CH-CH-CH-CH3


4-ethyl-2,3,-dimethylheptane

CH2 CH3 CH3

CH3
1. Find the longest chain of carbons in the molecule. This chain is considered
the parent structure. In the example, the longest chain contains seven
carbon atoms. Therefore, the parent hydrocarbon structure is heptane.
2. Number the carbons in the main chain in sequence. To do this, start at the
end that will give the groups attached to the chain the smallest numbers.
3. Add numbers to the names of the substituents groups to identify their
positions on the chain. These numbers become prefixes to the name of the
parent alkane. In this example, the substituents and positions are 2 –
methyl, 3-methyl, and 4-ehtyl.
4. Use prefixes to indicate the appearance of the group more than once in the
structure. Common prefixes are di-(twice), tri-(three times), tetra-(four times),
and penta-(five times). This example has two methyl substituents. Thus the word
dimethyl will be part of the complete name.
5. List the names of alkyl substituents in alphabetical order. For purposes of
alphabetizing, ignore the prefixes di, tri-, and so on. In this example the 4-ethyl
group is listed before the 2-methyl and 3-methyl groups (which are combined as
2,3-dimethyl in the name).
6. Use proper punctuation. This is very important in writing the names of organic
compounds in the IUPAC system. Commas are used to separate numbers,
Hyphens are used to separate numbers and words. The entire name is written
without any spaces.
Practice: Name these compounds according to the IUPAC system.
1. CH2-CH2-CH-CH2-CH3

CH3

CH2

CH3
3-ethylhexane
2.
H CH3 H
  
CH3 – CH2- C – C - CH3
  
CH3 H H
2,3,-dimethyl pentane
Unsaturated compounds: contain double or triple carbon-carbon bonds.
Saturated compounds: contain maximum number of hydrogen.
Alkenes: contain 1 or more C-C double covalent bonds.
Naming Alkenes:
1. Find the longest chain that contains the double bond= parent alkene. Root Name + ene
ending.
2. Chain is numbered so that the C atoms of the double bond get the lowest possible
numbers.
Ex: CH2=CH-CH2=CH3 1-butene
Alkynes: contain one or more C-C triple covalent bonds.
Practice: 1. How many H atoms in Ethane, Ethene, Ethyne
6, 4, 2,
2. Draw and name all the alkenes with the molecular formula C4H8
1- butene,
2-butene,
methylpropene
Isomer: same molecular formula but different moleuclar structure.
Hydrocarbon Rings: 5 & 6 member rings are most abundant.
Benzene: alternating double bonds.
Have resonance so bonding electrons are shared evenly around the ring.
Functional Groups: a specific arrangement of atoms in an organic compound that is
capable of characteristic chemical reactions.
Alcohols: OH group, hydroxyl group.
to name drope -e ending of parent alkane name and add -ol. when naming number the
position of the hydroxyl the lowest possible number on longest continuous chain.
CH3-CH2-OH ethanol
Carboxylic Acids: COOH group, carboxyl group. weak acids, ionize slightly in solution.
-COOH <--> COO- + H+
to name: drop -e ending of parent alkane name and add oic acid
CH3COOH ethanoic acid.(acetic acid)
Polymerization:
Polymer: large molecule formed by the covalent bonding of repeating smaller molecules.
Monomer: smaller molecules that combine to form polymer.
Carbohydrates:
monomer: monosaccharide
C6H12O6 + C6H12O6
polymer: polysaccharide (ex: starch)
------->
- H2O
C12H22O11
Proteins:
Monomer: amino acids
polymer: polypeptide
R
R
R
R
I
I
I
I
NH2- C- COOH + NH2- C- COOH --------> NH2- C- CO-NH- C- COOH
I
I
- H2O
I
I
H
H
H
H
Practice:
1. Draw 2-butanol
C-C-C-CI
OH
2. Draw pentanoic acid
C-C-C-C-COOH
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