Download functional groups 1. PPT

- Functional Groups
- Halogens, Alcohols & Ethers
Functional Groups
Besides hydrogen or carbon bonded to carbon
Many other atoms can bond to carbon and these
Lead to the formation of what are called
“Functional groups”
Each Functional group has it’s own unique chemical
And physical properties
So what kind of functional groups are there?
Check out Table R in your Reference Table.
TABLE R – Functional Groups
-Halides
-Alcohols
-Ethers
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.
Properties of Alkyl Halides
Alkyl halides are extremely unreactive
Often used when chemical inertness
is important
-Examples: CFC’s (refrigerants, Aerosol
propellants, Teflon (polymer), Brominated
compounds (Fire retardant clothing)
-many of these compounds are now banned
from use for health and environmental
reasons.
Properties of Alkyl Halides
 Alkyl halides due to there high molecular wt. have
considerably higher B.P. than their corresponding alkanes
Propane
Chloropropane
Bromopropane
B.P. (deg. C)
-42
47
71
Density (g/ml)
(Gas)
.890
1.335
 Bonds are polar but compounds are not soluble in water
 Probably because they can’t form H bonds
Is CHCl3 a polar compound? Yes
What about CCl4?
No
Naming Organic Halides
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 by numbering C-atoms in
backbone so that the halide has the lowest number.
c-c-c-c-c
Br Br
2,3-dibromopentane
Naming Halides
CH3Cl
CH3CHFCH3
H
H–C–Cl
H
H H H
H–C–C–C–H
H F H
Chloromethane
“Chloroform”
2-fluoropropane
C3H7F
Name the following Compound:
CH3CCl2CHClCH3
H Cl H H
H–C–C–C–C–H
H Cl Cl H
2,2,3-trichlorobutane
C4H7Cl3
Name this compound:
3-Bromo-2-Iodopentane
Name this compound:
F
H-C
F
Cl
1,1-dicloro-2,2-difluoroethane
Cl
One of the “freons”
C-H
Alcohols
• Alcohols contain the polar -OH functional group
– OH groups are capable of Hydrogen bonding
• This polar functional group affects physical
properties
– B.P is much higher than the corresponding Alkane
• Ethanol (C2H5OH) +78C // Ethane (C2H6) -89C
– Low Mol. Wt. Alcohols are very soluble in water
Hydroxyl groups
Alcohols can hydrogen bond because they have a
Hydrogen atom that is bonded to oxygen.
This results in
Much higher B.P.’s
And higher water
solubulity
CH3–CH2–O-H
CH3–CH2–O-H
H-O-H
Physical properties of Alcohols
Name
Formula
B.P. (C)
Sol.
(g/100g H20)
Methanol
CH3OH
64.5
Fully miscible
Ethanol
CH3CH2OH
78.3
Fully miscible
Propanol
CH3(CH2)2OH
97
Fully miscible
Butanol
CH3(CH2)3OH
118
7.9
Naming Alcohols
• Select as the parent structure the longest continuous
carbon chain that contains the –OH
• Drop the –e from the alkane name of the carbon chain and
add –ol
• Indicate by a number (if necessary) the position of the –OH
group
ethanol
2-propanol
Types of Alcohols
 Alcohols are also considered to be either
- primary, secondary, or tertiary alcohols
 Designations correspond to which carbon atom
the –OH group is bonded to
- Affects Chemical Reactivity/Properties
- Tertiary more reactive than Primary
Primary alcohol:
Secondary alcohol:
Tertiary alcohol:
OH bonded to –CH20H
OH bonded to –CHOH
OH bonded to -COH
Types of Alcohols
Primary alcohol
Secondary Alcohol
Tertiary Alcohol
Ethers
 Even though ethers have an oxygen atom in their
Structure they are unable to form hydrgen bonds with
themselves
- alkyl groups are bonded directly to Oxygen
- No hydrogen bonded to Oxygen
 Ethers are not linear; They have a bent shape similar to water
Ether’s Properties
 BP’s tend to be low
Comparable to similar MW hydrocarbons
No internal H-bonding
 Solubility in water is reasonably high for lower
M.W. ethers
H-Bonding to Water is possible
Propane
Dimethylether
Diethylether
M.W.
44
46
74
B.P. (deg. C)
-42
-24
35
Sol in Water
(g/ml)
Na
Na
8
Naming Ethers
(common names)
• Name the groups (alkyl) on either side and add ether to the
end.
• List attached alkyl groups in order of increasing size
• If they are the same the side chain is labeled “Di”
• NO NUMBERS NEEDED to designate location of Oxygen!
Naming Ethers
Name this compound:
Dimethyl ether
Name this compound:
Ethylpropyl ether