Download Notes, Part II

Classes of Organic Compounds
Mr. von Werder, WLHS
Halocarbons, Alcohols, and Ethers
► Hydrocarbons are plentiful, but when you start considering these hydrocarbons with some simple
substitutions there are even more compounds to consider.
► Here we will consider some of the main categories of organic compounds beyond hydrocarbons.
We will learn to recognize each category and learn to name several of them.
Functional Groups – an atom or group of atoms that has a characteristic chemical behavior (function)
 Halocarbons
 One or more of the hydrogens in a hydrocarbon has been replaced by a halogen(s)
R-X
 Recall: halogens are group 17 on the periodic table (F, Cl, Br. I)
X = F, Br, Cl or I
 NAMING halocarbons
 Name the halogens as branches off the main carbon chain
 The halogens are prefixes (fluoro-, chloro-, bromo-, iodo-) to the hydrocarbon name
 Use numbers to indicate the halogen position(s)
 Examples:
 Common examples/uses of halocarbons
 CFCs; chlorofluorocarbons; used as a refrigerants
 Being phased out in some applications; replaced with HFCs; hydrofluorocarbons
 CCl4; tetrachloromethane (common: carbon tetrachloride);
 Was a dry cleaning solvent (however, toxic and suspected carcinogen)
 Being replaced with dichloromethane
 DDT; largely used as a pesticide decades ago; but use was banned in the U.S. in 1972
 http://www.chem.ox.ac.uk/mom/ddt/ddt.html
 Used as intermediates in chemical reactions.
R - OH
 Alcohols
 One or more of the hydrogens in a hydrocarbon has been replaced by a hydroxyl group (-OH)
 Note: the –OH group here does not dissociate in water; so is chemically different than the hydroxide ion (OH-)
 The –OH group in alcohols makes them reasonable polar in small molecules (up to 4 carbons), and so
they dissolve well in water. (Why not longer chained alcohols?)
 NAMING alcohols – we’ll stick to the simple ones.
 Drop the “e” from the end of the hydrocarbon chain and add “-ol”
 If necessary, provide the lowest number for the position of the –OH group
 Examples:
 Common examples/uses of alcohols
 Methanol (common: methyl alcohol)
 Used to “denature” ethanol; “poisons” the ethanol making it unfit to drink. Why do that?
 Ethanol (common: ethyl alcohol, grain alcohol)
 The “alcohol” in alcoholic beverages – the intoxicating substance
 Naturally produced through fermentation of glucose
 2-propanol (common: isopropyl alcohol, rubbing alcohol)
 Used as a base for perfumes, creams, lotions, etc.
 1,2-ethandiol (common: ethylene glycol)
 Used mainly in antifreeze
 1,2,3-propantriol (common: glycerol)
 Used also as base in soaps, cosmetics, foods, pharmaceuticals…look for it.
 Ethers
 Ether – compound in which an oxygen atom bonded to two carbon atoms
 NAMING ethers – I’m not holding you to it.
R–O–R
Aldehydes and Ketones
 Carbonyl group O
- carbon atom is double bonded to an oxygen atom
– C – - found in aldehydes and ketones
 Aldehydes
 Organic molecules with a carbonyl group at the end of the carbon chain
 NAMING aldehydes – I’m not holding you to it.
 Methanal (common: formaldehyde) has been used to preserve biological specimens
O
R–C–H
 Ketones
 Organic molecules with a carbonyl group not at the end of the carbon chain.
 NAMING ketones – I’m not holding you to it.
 Propanone (common: acetone) is commonly used as a solvent; nail polish remover
O
R – C – R’
Carboxylic Acids and Esters
 Carboxyl group
- carbon atom is double bonded to an oxygen AND single bonded to a hydroxyl group
- found in carboxylic acids and in a slightly modified form in esters
 Carboxylic Acids
 Organic molecules with a carboxyl group (must be at the end of the carbon chain)
 NAMING carboxylic acids – we’ll stick to the simple ones.
 Drop the “e” from the end of the hydrocarbon chain and add “-oic acid”
 Methanoic acid (common: formic acid) first extracted from ants
 Ethanoic acid (common: acetic acid); the acid in vinegar
H-N C
 The carboxyl group is an important part of amino acids
O
R – C – OH
O
C O-H
H H
 Esters
 Organic molecules with a “carboxyl group” having the H replaced with more carbon(s)
 NAMING esters – we’ll stick to the simple ones.
 Name the carbon branch bonded to the oxygen in the chain
 Then name the carbon portion containing the double bonded oxygen by
dropping the “e” and adding “-oate”
O
R – C – O-R’
 Esters are usually formed by the reaction of an alcohol and a carboxylic acid (DEMO).
 Many esters have pleasant odors and are natural and synthetic fragrances and flavors.
Amines and Amides
 Nitrogen forms a couple of notable functional groups:
- Amines; containing an amino group (-NH2)
- Amides
 Amines
 Organic molecules with an amino group
 NAMING amines – I’m not holding you to it.
 The amino group is an important part of amino acids
O
H-N
C
H
H
R – NH2
C O-H
 Amides
 Organic molecules with an amino group attached to the carbon of a carbonyl group
 NAMING amides – I’m not holding you to it.
 The amide bond (peptide bond) is the result of amino acids linking together.
O
H-N
C
H
H
C O-H
O
O
+ H-N
C
H
H
C O-H
O
R – C – NH2
O
H-N
C
C N
C
H
H
H
H
C O-H
+
H2O