Transcript Regents Unit 15b: Halides, Alcohols, & Ethers

Hydrocarbon Derivatives:
Halocarbons, Alcohols, & Ethers
Hydrocarbons
• Contain only carbon & hydrogen
• But carbon can form strong covalent
bonds to other elements, incl. O, N, F, Cl,
Br, I, S, & P
Functional Group
• One or more H’s in a hydrocarbon can be
replaced by an atom or group of atoms.
• An atom or group of atoms in an organic
molecule that always behaves in the same way
is called a functional group.
• Adding a functional group changes the chemical
& physical properties in specific ways,
depending on the functional group.
Intermolecular Forces
• Determine Boiling Point & Solubility
• Van der Waals or dispersion – nonpolar –
weakest.
• Dipole-dipole – intermediate. Molecule
must have atoms with different
electronegativities & not arranged
symmetrically.
• Hydrogen bonding – strongest. Molecules
must contain H bonded to F, O, or N.
Functional Groups
•
•
•
•
•
•
•
•
Halocarbons
Alcohols
Ethers
Amines
Aldehydes
Ketones
Carboxylic Acid
Ester
• Amide
• Amino Acid
Organic Halides
• One or more of the hydrogen atoms in an
alkane is replaced with a halogen (F, Cl,
Br, or I).
• Not hydrocarbons! Often called
halocarbons or alkyl halides.
Naming Halides
• Figure out the base name.
• Use prefixes to specify substituent: fluoro,
chloro, bromo, iodo
• If more than one, use di, tri, etc. to specify
# of substituents.
• If necessary, give locations of halogens by
numbering C-atoms in backbone.
CH3Cl
CH3CHFCH3
H
H–C–Cl

H
H H H

H–C–C–C–H



H F H
chloromethane
2-fluoropropane
C 3H 7F
Naming Halides
CH3CCl2CHClCH3
H Cl H H
H–C–C–C–C–H
H Cl Cl H
2,2,3-trichlorobutane
C4H7Cl3
Ranking Halogens
• If more than 1 kind of halogen atom, list
them alphabetically.
• Chain is numbered to give lowest number
to halogen that comes first in alphabet.
Different Halogens
4
3
2
1
Chlorine is 1st alphabetically, so it
determines numbering.
2-chloro-4-fluoro-3-iodobutane
Name:
Br
CH3CH2CHCHCH3
I
3-bromo 2-iodo pentane
F Cl
HCCH
F Cl
1,1-dichloro-2,2-difluoroethane
Properties of Halocarbons
• For an alkane & an alkyl halide of similar
size & shape, the alkyl halide has the
higher boiling point & higher density.
Why? Stronger intermolecular forces.
• CH4: bp = -162C & density = 0.423 g/ml
• CH3Cl: bp = -24C & density = 0.911 g/ml
What intermolecular forces for CCl4?
CH3CH2CH2CH2CH3
pentane
CH3CH2CH2CH2CH2F
1-fluoropentane
CH3CH2CH2CH2CH2Cl
1-chloropentane
CH3CH2CH2CH2CH2Br
1-bromopentane
CH3CH2CH2CH2CH2I
1-iodopentane
Boiling Point
(C)
36
Density
(g/ml)
0.626
63
0.791
Inc
108
0.882
130
1.218
155
1.516
Inc
Uses of Alkyl Halides
• Cleaners & solvents
• Teflon & PVC’s are alkyl halides.
• Refrigerants. (used to be
chlorofluorocarbons. Now
hydrofluorocarbons.)
• Starting materials in many reactions.
Halogen Derivatives
•
•
•
•
•
•
CH3Cl = local anesthetic
CHCl3 = solvent, general anesthetic
CHI3 = antiseptic
CCl4 = dry cleaning solvent
CF2Cl2 = refrigerant
Fluorocarbons = teflon, lubricants, synthetic
blood
• Chlorofluorocarbons = aerosol propellants,
refrigerants
Table R
• General Formula for halocarbons: R-X
• R represents the entire hydrocarbon part
of the molecule. (The alkyl part.)
• X represents the halogen (F, Cl, Br, or I).
Alcohols
• An –OH group replaces a H in a
hydrocarbon.
• The –OH group is called the hydroxyl group.
H
HCH

H
-OH
H

HCOH

H
Alcohols are nonelectrolytes!
• The hydroxyl group resembles the
hydroxide ion of inorganic bases, but it
does not form ions in water!
• The hydroxyl group is polar. So alcohols
are soluble in water.
Naming AlcohOLs
• Based on alkane name.
• Name the parent chain.
– Drop the –e and add –OL.
• If the parent chain has 3 or more C atoms,
number the C’s & give the location of the –
OH group.
Naming
H H H H
HCCCCH
OH H H H
1-Butanol
bp = 100C
H H H H
HCCCCH
H OH H H
2-Butanol
Bp = 115C
Note: Never more than 1 –OH group per C
More than 1 hydroxyl group
• Prefixes di-, tri-, tetra- used before the –ol
ending to tell the # of hydroxyl groups.
• So don’t drop the -e from the alkane
name.
• These hydroxyls are on different C atoms!
Classifying Alcohols
• By # of hydroxyl groups
–Monohydroxy: 1 hydroxyl group
–Dihydroxy: 2 “ “
–Trihydroxy: 3 “ “
• By position of each hydroxyl group on
main carbon chain.
Monohydroxy Alcohols
• Primary: hydroxyl group attached to end
C of chain or branch.
• Secondary: hydroxyl group attached to C
in a chain – C is bonded to 2 other C’s.
• Tertiary: hydroxyl group attached to C at a
branch point – C is bonded to 3 other C’s.
HHHH
H-C-C-C-C-O-H
HHHH
HHHH
H-C-C-C-C-H
HHOH
H
1-butanol
primary
2-butanol
secondary
H
H-C-H
H H
H-C-C-C-H
HOH
H
2-methyl 2-propanol
Tertiary
HH
H-C-C-H
OO
HH
Dihydroxy
HHH
H-C-C-C-H
OOO
HHH
Trihydroxy
Properties of Alcohols
• Contain a H bonded to an O atom.
• Therefore Hydrogen Bonding occurs.
• Alcohols have a higher boiling point than
the corresponding alkane.
• Like dissolves Like. Alcohols tend to be
very soluble in water.
R
R
-
O
H
+
O
H
+
-
Which compound has the highest
boiling point?
A.
B.
C.
D.
CH4
C 2H 6
C 3H 8
C3H7OH
Correct response = D.
Table R
• General Formula for Alcohols: ROH.
• R represents the entire hydrocarbon part
of the molecule.
• OH is the hydroxyl group.
Ethers
• General formula is ROR where R may
or may not be the same as R.
• R and R are hydrocarbon branches.
• O is an oxygen bridge.
• Ethers are not linear. They are bent, like
water.
Properties of Ethers
• In a pure ether, no hydrogen bonding – no
H bonded to O. Do have weak dipoledipole interactions – bent, like H2O.
• Dipole-dipole interactions are between
dispersion forces & hydrogen bonding.
• Ethyl ether once used as anesthesia
Properties of Ethers
• Compared to alkanes:
– Higher boiling pts than similar alkanes.
– More soluble in water than alkanes.
• Compared to alcohols:
– Lower boiling pts than similar alcohols.
– Much less soluble in water than alcohols.
Naming Ethers
• If the 2 hydrocarbon branches are
identical, name the branch (once) & add
the word ether.
• If the 2 branches are different, list them in
alphabetical order followed by the word
ether.
H
H
HCOCH
H
H
Methyl Ether
H H H
H H H
HCCCOCCCH
H H H
H H H
Propyl Ether
H
H H H
HCOCCCH
H
H H H
Methylpropyl Ether