Organic Chemistry ppt 2012

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Organic Chemistry
= the study of carbon and
most carbon compounds
Bonding of Carbon Atoms
 Carbon atoms have a tendency to covalently bond with other carbon atoms and form
chains.
Straight chains
Branched chains
Ring chains
 Carbon atoms are able to form up to four covalent bonds:
**Remember: Carbon has 4 valence electrons.
 Carbon atoms can engage in single, double, or triple
covalent bonds:
saturated compounds = contain only single bonds
unsaturated compounds = contain at least 1 double or
triple bond
Saturated and Unsaturated fatty acids
This double bond between the two
carbon atoms makes this organic
compound unsaturated.
Molecular vs. Structural
Formulas
Molecular Formulas – show the atoms and the number of atoms involved in a
molecule but nothing else (ex: propane is C3H8 )
Structural Formulas – show each type of atom and how they are arranged in a
molecule. The Condensed Structural formula of propane is CH3CH2CH3
Molecular Formula
Structural Formula
Condensed Structural Formula
CH4
CH4
C 2 H6
CH3CH3
Hydrocarbons
= organic compounds that contain only atoms of hydrogen and carbon
 Homologous series of hydrocarbons:
(a) Alkanes = contain only single covalant bonds
- General formula: CnH2n+2
(b) Alkenes = contain one double covalent bond
- General formula: CnH2n
(c) Alkynes = contain one triple covalent bond
- General formula: CnH2n-2
Naming Organic Compounds
(also see Mr. Caiafa’s ppt)
 Naming straight-chained hydrocarbons:
 Use Reference Table P (Organic Prefixes) and Table Q (Homologous
Series of Hydrocarbons) to name & write the formulas.
 When naming alkenes & alkynes, indicate where the double/triple bond
is located in the molecule.
The double bond is
located on the 1st
carbon…so its name
would be: 1-butene
**The carbons are numbered so as to keep the
number for the double bond as low as possible**
Both compounds
have four carbons
(use prefix but-)
and a double bond
(use ending –ene)
The double bond is
located on the 2nd
carbon…so its name
would be: 2-butene
Both compounds
have four carbons
(use prefix but-)
and a triple bond
(use ending –yne)
The triple bond is located
on the 2nd carbon…so its
name would be: 2-butyne
The triple bond is located
on the 1st carbon…so its
name would be: 1-butyne
Naming Organic Compounds
 Naming branched hydrocarbons:
1) Find the longest carbon chain which contains the functional group or multiple bond if present and
name it (using Tables P & Q to find correct prefix & ending).
2) Number the longest chain (left to right or right to left) so that the functional group/multiple bond/longest
side chain (branch) is on the lowest numbered carbon possible.
3) Name each side group but change the ending to -yl.
4) Use a prefix di-, tri-, tetra-, etc. to denote how many side groups of each length are present.
5) Before naming the side group give the number of the carbon to which the side group is attached.
6) Arrange the side groups in alphabetical order ignoring the prefixes di-,tri-, etc.
Examples:
3.) The side group has only one
carbon, so use the prefix methand add the ending –yl: methyl.
1.) The longest chain has
5 carbons, so the prefix
pent- must be used.
2.) There are only single
bonds, so the ending –ane
must be used.
Name: 3-methyl pentane
4.) Since the side group is right in
the middle, the carbons can be
numbered from either side. The
methyl group is located on the 3rd
carbon.
3.) Each side group has only one
carbon, so use the prefix methand add the ending –yl: methyl.
Since there are 3 methyl groups,
use the prefix tri-: trimethyl.
1.) The longest chain has 4
carbons, so the prefix butmust be used.
2.) There are only single
bonds, so the ending –ane
must be used.
Name: 2,2,3-trimethyl butane
4.) Count carbons so that the
longest side chain has the lowest #.
The first 2 methyl groups are located
on carbon 2, and the next methyl
group is located on carbon 3.
Isomers
= compounds with the same molecular formula, but different structural
arrangements
**As the # of carbon atoms in a compounds increases, the # of possible
isomers also increases.**
Example of Isomers:
All of these compounds
have the molecular
formula C5H12 except
for compound (4) which
is C5H10
Functional Groups
=
atoms or groups of atoms that can replace hydrogen atoms in a
hydrocarbon and give the compound distinctive physical and
chemical properties
(1) Halides:
= when any of the halogens
(F, Cl, Br, or I) replaces a hydrogen
atom in an alkane
- named by citing the location of the
halogen attached to the chain and
adding the appropriate prefix
(fluoro-, chloro-, bromo-, or
iodo-)
Note: Table R provides examples
on how to recognize and name
compounds w/ each of the
functional groups!
(2) Alcohols:
= one or more hydrogen atoms of a hydrocarbon are replaced by
an –OH group (called a hydroxyl group)
Note: The –OH group does not
dissociate, and therefore alcohols
- named by citing the location of the –OH
are not bases/electrolytes.
However, the –OH group does make
group and changing the ending to –ol.
alcohols polar molecules.
- Classifying alcohols:
Monohydroxy alcohol:
one –OH group
Dihydroxy alcohol:
Trihydroxy alcohol:
two –OH groups
three –OH groups
- Alcohols can also be classified according to the
position of their –OH group:
PRIMARY (1o): the functional group is
bonded to a carbon that is on the end of
the chain.
SECONDARY (2o): The functional
group is bonded to a carbon in the
middle of the chain.
TERTIARY (3o): The functional group
is bonded to a carbon that is itself
directly bonded to three other carbons.
(3) Aldehydes:
= the carbonyl group (-C=O) is found on the end carbon and is
bonded to a H atom
- named by substituting –al in place of the final –e of the
corresponding alkane name
(4) Ketones:
= the carbonyl group (-C=O) is found on an interior carbon atom
that is attached to two other carbon atoms
- named by replacing the final –e from the corresponding alkane
with –one; if necessary, cite which carbon atom the carbonyl
group is attached to.
(5) Ethers:
= two carbon chains are joined together by an oxygen atom
with single bonds to two carbon atoms
- named by first naming the two methyl groups, followed by the
word ether (when both R groups are the same, use prefix di-)
(6) Organic Acids (carboxylic acids) are weak acids:
= contain the carboxyl functional group (-COOH)
- named by replacing the –e in the corresponding alkane name
with –oic acid
(7) Esters:
= have the type formula R-CO-OR’ (R-CO-O- part of formula
comes from an organic acid; the R’ part comes from an alcoholsee Esterification)
- named for the alcohol and organic acid that make up the ester
(8) Amines:
= formed when one or more of the hydrogen atoms of ammonia
are replaced by an alkyl group (ex CH3NH2 is methanamine)
- named by changing the alkane ending of –e to –amine and then
numbering the alkane chain to show the location of the amine
group
(9) Amides:
= a compound formed by the combination of an amine with a
carboxylic acid; recall from biology that amide groups are formed when
amino acids condense to form a peptide bonds
(See Condensation reaction)
- named by changing the carboxylic acid
acid reactant ending –oic acid with
-amide
Organic Reactions
(also see Mr. Caiafa’s ppt)
**Note: Generally occur more slowly than inorganic reactions. When covalently
bonded substances react, they must first break relatively strong existing
bonds before making new bonds.**
(1)
Combustion:
= Hydrocarbons burn in the presence of oxygen to produce water
and carbon dioxide
(2) Substitution:
= involves the replacement of one or more of the hydrogen atoms
a saturated hydrocarbon with another atom or group
(3) Addition:
= involve adding one or more atoms at a double or triple bond
Examples:
Ethene (CH2=CH2) and Chlorine (Cl2) react to form 1,2-dichlorethane
2-Butene (CH3CH=CHCH3) and Hydrogen (H2) react to form Butane (CH3CH2CH2CH3)
in
(4) Esterification:
= the reaction between an organic acid and an alcohol to produce an ester
plus water
Organic Acid + Alcohol  Ester + Water
(5) Saponification:
= when an ester reacts with an inorganic base to produce an alcohol and a
soap
(6) Fermentation:
= a chemical process in which yeast cells secrete the enzyme zymase and break
down sugar into carbon dioxide and two carbon fragments of alcohol
(7) Polymerization:
= the formation of large polymer molecules
Polymers = organic compounds
make up of chains of smaller units
covalently bonded to each other
(a) Addition polymerization
= involves the joining of monomers of unsaturated compounds
(b) Condensation polymerization
= involves the joining of monomers by removing water from
hydroxyl groups and joining the monomers by an ether or ester
linkage
Addition Polymerization:
Condensation Polymerization:
H2O
First 10 Alkanes in Series
Hydrocarbon
Molecular Formula
Methane
CH4
Ethane
C 2H 6
Propane
C 3H 8
Butane
C4H10
Pentane
C5H12
Hexane
C6H14
Heptane
C7H16
Octane
C8H18
Nonane
C9H20
Decane
C10H22
First 10 Alkenes in Series
Hydrocarbon
Molecular Formula
Ethene
C 2H 4
Propene
C 3H 6
Butene
C 4H 8
Pentene
Hexene
Heptene
Notice: There is no alkene
corresponding to the
methane of the alkane
series. That is b/c there
must be at least 2 carbon
atoms to form a double
bond.
C5H10
C6H12
C7H14
Octene
C8H16
Nonene
C9H18
Decene
C10H20
First 10 Alkynes in Series
Hydrocarbon
Molecular Formula
Ethyne
C 2H 2
Propyne
C 3H 4
Butyne
C 4H 6
Pentyne
Hexyne
Heptyne
Notice: There is no alkyne
corresponding to the
methane of the alkane
series. That is b/c there
must be at least 2 carbon
atoms to form a triple bond.
C5H8
C6H10
C7H12
Octyne
C8H14
Nonyne
C9H16
Decyne
C10H18

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