Transcript Chapter 26 Functional Groups and Organic Reactions

“Organic compounds and
Nomenclature”
Root of the name
This depends on the number of carbon
atoms in the longest unbroken chain.
1 carbon chain …. Meth2 carbon chain …. Eth3 carbon chain …. Prop4 carbon chain …. But5 carbon chain …. Pent
The “default”
This is a hydrocarbon that contains only
single bonds. It has the suffix (ending) –
ane
Example
A three carbon chain with only carbons,
hydrogens and single bonds is called
propane. CH3CH2CH3

Unsaturation



If a molecule contains double or triple bonds
it is said to be unsaturated (meaning that it
would be possible to fit in more hydrogens if
the double bonds were changed to single).
Chains with one double bond take the suffix ene. Example: ethene CH2=CH2
Chains with one triple bond take the suffix –
yne. Example: Ethyne CHΞCH
Functional Groups
 Most
organic chemistry involves
substituents
–often contain the elements O, N,
S, or P
–also called “functional groups”they are the chemically functional
part of the molecule, and are the
non-hydrocarbon part
Functional Groups
 Functional
group - a specific
arrangement of atoms in an
organic compound, that is
capable of characteristic chemical
reactions.
–What is the best way to classify
organic compounds? By their
functional groups.
Functional Groups
 The
symbol “R” is used to
represent any carbon chains or
rings
 These
are called alkyl groups
 CH3 - methyl group
 CH3CH2 - ethyl group
 CH3CH2CH2 - propyl group
Halogen Substituents
- class of
organic compounds containing
covalently bonded fluorine,
chlorine, bromine, or iodine
 Halogenocarbons
–General formula: R-X
 Naming? Name parent as normal,
add the halogen as a substituent (or
prefix) -
Halogen Substituents
The more highly halogenated the
compound is (I.e. the more greater the
number of halogen atoms), the higher
the b.p.
 Few halogenoalkanes are found in
nature….
– but, readily prepared and used
– halothane and also the
hydrofluorocarbons

Alcohols and Ethers
 OBJECTIVES:
–Describe the structures and
naming of alcohols and
ethers.
Alcohols
Alcohols - a class of organic
compounds with an -OH group
– The -OH functional group in alcohols
is called a “hydroxyl” group; thus ROH can represent the formula, where
“R” is an alkyl group
 How is this different from the hydroxide
ion? (covalently bonded to the carbonnot ionically as in hydroxides)

Alcohols
Both systematic and common names
 systematic:
– drop the -ane ending of the parent
alkane name; add ending of -anol,
number the position of –OH if needed
– parent is the longest chain that
contains the carbon with the attached
hydroxyl.

Alcohols
 The hydroxyl group is given
the lowest position number
 Alcohols containing 2, 3, and 4
of the -OH substituents are
named diols, triols, and tetrols
respectively (not needed fro
year 10)
Alcohols
 Common names:
–similar to halogenoalkanes,
meaning name the alkyl
group root followed by the
suffix -anol
–One carbon alcohol = methanol = methanol
Properties of Alcohols
 Glycerol
(propan 1,2,3 triol) - used
as a moistening agent in cosmetics,
foods, and drugs; also a
component of fats and oils
 Ethyl alcohol (ethanol) used in the
intoxicating beverages; an
important industrial solvent
Ethers
A class of organic compounds in which
oxygen is bonded to 2 carbon chains:
R-O-R is the formula
 Nomenclature: The larger of the two R
groups is the root and the other R group
is prefixed as alkoxyExample:
CH3CH2OCH3 methoxyethane

Alkanals and Alkanones
 The
C=O group is called the
“carbonyl group”
–it is the functional group in both
alkanals and alkanones
 Alkanals - carbonyl group always
joined to at least one hydrogen
(meaning it is always at the end!)
Alkanones
 Alkanones
- the carbon of the
carbonyl group is joined to two
other carbons (meaning it is
never on the end)
Alkanals and alkanones
 Nomenclature
–Alkanals: identify longest chain
containing the carbonyl group, then
the -ane ending replaced by -anal,
such as methanal, ethanal, etc.
–Alkanones: longest chain with the
carbonyl, then new ending of anone; number it
 propanone, 2-pentanone, 3-pentanone
Aldehydes and Ketones
 Propanone
(common: acetone) is a
good solvent; miscible with water in
all proportions
 why is it a good substance used in
nail-polish removers? (a powerful
solvent-able to dissolve both polar
& non-polar substances)
Carboxylic Acids
 Also
have a carbonyl group (C=O),
but is also attached to a hydroxyl
group (-OH) = “carboxyl” group
 general formula: R-COOH
–weak acids (only slightly
dissociate into ions)
 Named by replacing -ane with anoic and followed by the word acid
 methanoic acid; ethanoic acid
Carboxylic Acids
 Abundant
and widely distributed in
nature, many having a Greek or
Latin word describing their origin
–acetic acid (ethanoic acid) from
acetum, meaning vinegar
–many that were isolated from fats
are called fatty acids