Transcript principle group

Chapter 8
Introduction to Alkyl Halides, Alcohols, Ethers,
Thiols, and Sulfides
Alkyl Halides
• Organic compounds containing at least one carbon-halogen
bond (C-X)
– X = F, Cl, Br, or I
– X replaces an H
• Properties and some uses
– Fire-resistant solvents
– Refrigerants
– Pharmaceuticals and precursors
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Nomenclature
• Two systems:
1) Common
2) IUPAC
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Common Naming Rules
• Generally used only for simple compounds
1) Identify the alkyl group and name it as a substituent
• change the ending from “-ane” to “-yl,” if
applicable
2) Identify the halide and name it
3) Leave a space between the two names from steps 1
and 2.
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Alkyl Halides
• Other common names to learn:
8.1 Nomenclature
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IUPAC Naming Rules
1) Identify the longest carbon chain and name it as the parent
• Contains double or triple bond if present
2) Number the parent chain beginning at the end nearest any
substituent (alkyl or halogen)
3) If more than one of the same kind of substituent is present,
number each and use the Greek prefixes to indicate how
many
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4) If different substituents are equidistant from the
ends of the parent chain, begin at the end nearer
the substituent whose name comes first in the
alphabet.
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Problems
• Name the following alkyl halides using
common nomenclature
• Name the following alkyl halides using IUPAC
nomenclature:
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Problems
1) CHCl3 is commonly known as chloroform.
What is its IUPAC name?
2) Based on what you know from question #1,
what are the common and IUPAC names for
CHBr3, CHI3, and CHF3?
General Classifications
• Alkyl halides can be classifed as methyl,
primary, secondary, or tertiary based on the
number of organic groups bonded to the
halogen bearing carbon
8.1 Nomenclature
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Problem
• Draw 4-chloro-3,4-dimethyl-1-octene. Classify
this alkyl halide based on degree of
substitution.
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Alcohols
• Contain an OH group connected to
a saturated (sp3-hybridized)
Carbon
– Important solvents and synthesis
intermediates
– Methanol (Methyl Alcohol)
• Common solvent
• Fuel additive
– Ethanol (Ethyl Alcohol)
• Solvent
• Fuel
• Beverage
– Isopropanol (Isopropyl Alcohol)
• Rubbing alcohol
• Solvent
• Disinfectant
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Phenols
• Compounds containing an OH group
bonded to a carbon in a benzene ring
• Building polycarbonates, epoxies,
Bakelite, nylon, detergents and a
large collection of drugs, herbicides
and pharmaceuticals.
BPA
Eugenol
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Glycols
• Compounds containing two or more hyrodoxyl (-OH)
groups
– Diol: contains two –OH groups
• Geminal: OH’s are on the same carbon
• Vicinal: OH’s are on adjacent carbons
• General: OH’s located in non-geminal/nonvicinal positions
Ethylene Glycol
Resorcinol
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General Classification
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Nomenclature
• Two types:
– Common
– IUPAC
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Common Naming Rules
• Used for simple and common alcohols
1) Identify the alkyl group to which the hydroxyl group
is attached and name this as a substituent
• Ethane  Ethyl
2) Add the word “Alcohol”
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IUPAC Naming Rules
1) Select the longest carbon chain containing the hydroxyl
group, and derive the parent name by replacing the “-e”
ending of the corresponding alkane with “-ol “
2) Number the chain from the end nearest to the hydroxyl
group
3) Number substituents according to position on chain and
then list them in alphabetical order as usual
2-chloro-5-methyl-1-hexanol
Or 2-chloro-5-methylhexan-1-ol
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4) If there are more than one hydroxyl groups,
use Greek prefixes to indicate how many
•
Do not drop the final e of the alkane
5) If stereochemistry is known, indicate it
Naming Phenols
1) Use “phenol” (the French name for benzene)
as the parent hydrocarbon name, not
benzene
2) Name substituents on aromatic ring by their
position from OH
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Problems
1) Name the following molecules:
2) Classify the first two molecules above based
on level of substitution (1°, 2°, 3°
alcohol)
3) Draw the following molecules
–
–
1,2,3-propanetriol
2-ethyl-3-methylphenol
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Thiols
• Compounds that contain a carbon bonded to a
sulfhydryl group (-SH)
• Sulfur analogs of alcohols
• R-SH vs. R-OH
Ethanethiol
vs.
Ethanol
• Stinky molecules
• Also known as “Mercaptans”
• The –SH group is also called a “mercapto” group
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Nomenclature of Thiols
• Common:
– Named in the same fashion as alcohols
• The word mercaptan replaces alcohol in the
name of the equivalent alcohol compound
– Example: CH3SH would be methyl
mercaptan, just as CH3OH is called methyl
alcohol.
Methyl mercaptan
Methyl Alcohol
•
IUPAC
1) Identify the longest carbon chain containing the
sulfhydryl group. Name this chain and add “thiol” to
the end (no space).
2) Number the chain so that the carbon connected to
the –SH group has the lowest number possible
3) Name and number all of the substituents and place
them, in alphabetical order, in front of the parent
chain name.
2-hexanethiol
2-ethyl-1-hexanethiol
Problems
• Name the following compounds:
• Draw:
– 3,3-dimethyl-1-butanethiol
– 2-ethylcyclohexanethiol
– Trans-3-heptene-2-thiol
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Hmmmmm….
Principle Group and Principle Chain
• Principle Group: the functional group upon
which the name of a molecule is based
• Cited as the suffix in the name
• Example: Pentanol
• Have priorities in a molecule
• All other substituents are cited as prefixes (except
multiple bonds)
• Carboxylic acid > anhydride > ester > acid halide >
amide > nitrile > aldehyde > ketone >
alcohol/phenol > thiol > amine
8.1 Nomenclature
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1) Identify the principle group (e.g., -OH > -SH)
2) Identify the principle chain
•
•
The carbon chain on which is the name is based
Priorities for picking the principle chain:
a) The carbon chain with the greatest number of
principle groups
b) The carbon chain with the greatest number of double
and triple bonds
c) Of greatest length
d) With the greatest number of other substituents
Principle Group and Principle Chain
3) Number the carbons of the principle chain
giving the lowest numbers:
a)
b)
c)
d)
For the principle groups
For multiple bonds (C=C > CC)
For other substituents
For the substituent cited first in the name
8.1 Nomenclature
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Principle Group and Principle Chain
4) Begin construction of the name with the
name of the hydrocarbon corresponding to
the principle chain
a) Cite principle group by suffix and number
•
Will be last number in molecular name
b) If there is no principle group, name the
compound as a substituted hydrocarbon
c) Cite the names and numbers of other
substituents in alphabetical order
8.1 Nomenclature
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Problems
• Name the following compounds: