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- Functional Groups- Halogens, Alcohols & Ethers
Functional GroupsBesides hydrogen or carbon bonded to carbonMany other atoms can bond to carbon and theseLead to the formation of what are called “Functional groups”
Each Functional group has it’s own unique chemicalAnd 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
• NotNot 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
Bonds are polar but compounds are not soluble in water Probably because they can’t form H bonds
Is CHCl3 a polar compound?
What about CCl4?
Yes
No
Propane Chloropropane Bromopropane
B.P. (deg. C) -42 47 71
Density (g/ml) (Gas) .890 1.335
Naming Organic HalidesUse 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
HH–C–Cl H
Chloromethane
H H HH–C–C–C–H H F H
C3H7F
2-fluoropropane
“Chloroform”
Name the following Compound:
CH3CCl2CHClCH3
H Cl Cl H H
H – C C – – C C – – C C – – CC – H H Cl ClCl Cl H
2,2,3-trichlorotrichlorobutanebutane
C4H7Cl3
Name this compound:
3-Bromo-2-Iodopentane
Name this compound:
F ClH-C C-H F Cl
1,1-dicloro-2,2-difluoroethane
One of the “freons”
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 aHydrogen atom that is bonded to oxygen.
CH3–CH2–O-H
CH3–CH2–O-H
This results inMuch higher B.P.’sAnd higher watersolubulity
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 continuouscarbon 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: OH bonded to –CH20HSecondary alcohol: OH bonded to –CHOHTertiary alcohol: 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 hydrocarbonsNo 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:
Name this compound:
Dimethyl ether
Ethylpropyl ether