Unit 4 Chemistry of Carbon Organic Chemistry studies the compounds of the element carbon In many of these compounds carbon is found bonded to Hydrogen, oxygen, nitrogen, phosphorus, sulfur, and halogens Contrasting organic and inorganic compounds Type of Compound Organic Type of bonds Covalent Melting point Low Boiling point Low Combustibility Burns easily Number of molecules Millions Water solubility Mostly nonpolar (insoluble) Conductivity Nonelectrolytes Elements found in organic compounds Element Lewis dot structure Carbon C
Hydrogen
# of bonds
Inorganic Ionic High High Does not burn easily Thousands Most are polar or ionic (soluble) Electrolytes
Bond arrangements
H
Oxygen O
Sulfur S
Nitrogen
Halogens F, Cl, Br, I
3/08
N
Cl
1
Hydrocarbons: The simplest carbon compounds (Composed of only hydrogen and carbon.) The main source of hydrocarbons is oil. Importance of hydrocarbons: 1. Energy Small hydrocarbons (1-4 C’s) are gases, medium sized (5-17C’s) hydrocarbons are liquids, and big hydrocarbons (over 17 C’s) are solids like waxes. They burn well : CxHy +O2 Æ H2O + CO2 + energy (calories) There is a lot of energy given off when this reaction occurs. Liquid hydrocarbons are excellent fuels for cars and trucks or any other transportation form. 2. Building blocks for every day materials We have become dependent on plastics or, to use the chemical, term polymers. From car parts to fabrics to packaging, it is hard to find anything that does not contain plastics. Also the building blocks for many pharmaceutical drugs come from hydrocarbons. General formula Alkanes
CnH2n+2
saturated
Alkenes
Example Full Structural formula
H
CnH2n
H
H
H
C
C
C
H
H
H H
Condensed structural formula
H
Name
CH3CH2CH3
propane
CH2CHCH3
propene
CHCCH3
propyne
H
unsaturated
C
C
C
H
H H
H
H
Alkynes
CnH2n-2
unsaturated
H
C
C
C
H
H
Hydrocarbons can also have a ring structure: which is usually indicated by having cyclo in its name Benzene: (A cyclic structure that doesn’t use the phrase cyclo – because it is “special”) H C HC
CH
HC
CH C H
It has an aromatic structure, which is extremely stable and unreactive. It is unsaturated, but behaves as if it is saturated due to it’s high stability.
3/08
2
Types of Carbon Primary 1o Bonded to only 1 other carbon Secondary 2 o Bonded to 2 other carbons Tertiary 3 o Bonded to 3 other carbons Quarternary 4 o Bonded to 4 other carbons
H
H
CH3
H
H
H
H
C
C
C
C
C
C
H
CH3
H
H
CH3
H
H
Alkanes Name
Molecular
Full Structural formula
Condensed structural formula
Formula
CH4
H
Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Nonane
Decane
3/08
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
H
H
H
H
H
H
H
H
H
H
C
H
H H
H
C
C
H
H H
H H
H
C
C
C
H
H H
H H
H H
H
C
C
C
C
CH3CH3
CH3CH2CH3
CH3CH2CH2CH3 H
Or CH3(CH2)2CH3 CH3CH2CH2CH3
H H
H H
H H
H H
H
C
C
C
C
C
H H
H H
H H
H H
C
C
C
H H
H H
C
H
Or
H H
H
CH3(CH2)3CH3 CH3CH2CH2CH2CH2CH3
C
C
C
H H
H H
H H
C
C
C
H
H
H
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
H
H H
H H
H H
H H
H H
H H
H H H H
H
C
C
C
C
C
C
C
C
H H
H H
H H H H H H H H H H H H H H
H
C
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
H
H
Or
H H
H
CH3(CH2)4CH3 CH3CH2CH2CH2CH2CH2CH2CH3
C
C
C
H
H
H
Or
H
C
CH3(CH2)5CH3 CH3(CH2)6CH3
CH3(CH2)7CH3 H
CH3(CH2)8CH3 H
3
Side Chains and Side Groups (Subtituents) Name
Full Structure
Example
H
methyl
C
H
H
H H H H
C
C
H
H
H
isopropyl
fluoro
C
C
C
H
H
H
H
4-methyloctane
H
H
CH3H
H
ethyl
propyl
H
Name 2- methylpropane
H
H
H
C
C
C
H H
H
H H
C
C
C
H
H
H
H
C
H
H
C
H
H
H
H
C
C
C
H
H
H
H
H
H
H
C
C
C
C
C
H
H
H
H
H
CH3CH2CH2CH2CH2CHCH2CH2CH2CH3
5-propyldecane
CH2CH2CH3
4-isopropylheptane
CH3 H
H H
H
H
H
C
C
C
H
H
H
F
H
C C H
CH3 H
H
H
C
C
C
H
H
H
H
H
C
C
H
H
Cl
Cl
H
Fluoroethane F
Chloromethane
H
chloro
H
C
H
H
bromo
Br
H
H
Br H
C
C
H
iodo
3/08
I
H
2-bromopropane
C
H
H
H
H
H
H
H
C
C
C
C
H
H
H
H
1-iodobutane I
4
Classes of Compounds and Functional Groups Class of compound name Alkane
Functional group
C
C
Functional group description Single bonded carbons
Example Name Ethane H
Alkene C
Double bonded carbons
C
H
H
C
C
H
H
H
Ethene H
H C
C
H
Alkyne
C
Aromatic
C
C C
C
Triple bonded carbon atoms Aromatic ring of six carbons
H
Ethyne H
C
C
Benzene H H
H
C C
C
H
C
C
C
C
C C
H
H
H
Alcohol
O
H
hydroxyl
Methanol H 3C
Ether
Oxygen bonded to 2 carbons
O
Methoxymethane O H 3C
Aldehyde
C
carbonyl
O
OH
O
CH3
Methanal O
C
H H3C
Ketone
Carbonyl between 2 carbons
O
C
H
2-propanone O
C H3C
Carboxylic acid
carboxyl
O
C
CH3
Ethanoic acid O
C
OH H3C
Ester
Carboxyl group with H replaced by C
O C
Thiol
O S
O C
O
CH3
Methanethiol H3C
Amine
OH
Methylmethanoate H 3C
H
C
S
H
Amino methane H
N H 3C
Amide
C
3/08
N
H
O N
5
General naming Rules for organic compounds: For most compounds there are no spaces (there are exceptions) (Yes, these can get very long!) The following will give you a general idea of how to name simple organic compounds. 1. Find any functional groups present. That functional group will identify the ending in the name of the compound, it will also help you to determine the main chain. (ie. ane, ene, one, anol etc) 2. Find the longest continuous hydrocarbon chain which includes any functional groups. That main chain will identify the length of the main chain name used near the end of the name. (ie. 6 C’s in uses hex.) 3a) If there are no functional groups present (all single bonds and no O, N or sulfur, but there may be halogens) then: Number the carbons in this chain from the end that will give the side chains the smallest total number. 3b) If there is a functional group (other than halogens) then the functional group gets the lowest possible number and the direction of counting is determined by that. 4. Number the side chains with the number of the carbon they are attached to, followed by a hyphen and then the name of the side chain. (i.e. 2-methyl) 5. If there are more than one of the same side chain use the numbers (in numerical order) separated by commas and then use di, tri, tetra, penta, etc. (2,2,3-trimethyl) Remember that each side chain must have a number to tell where it is! 6. Number the functional groups by placing the number then a hyphen in front of the main chain length name. (ie.2-pentanone) 7. If there are more than one kind of side chain or functional group put them in alphabetical order with a hyphen separating any number and letter. (4-ethy-3-methyl) 8. Beware that some functional groups never require a number since they can only be in position 1 (ie aldehydes) 9. Rarely, the number need not be provided because the size of the carbon chain length limits the available positions of the functional groups. (ie. butanone not 2-butanone) 10. Some compounds have a cyclic structure, for most of those we add in the term cyclo in front of the main chain name and the numbering starts, by following the rule that functional groups get lowest numbers and then total number should be the lowest. (ie 2-methyl-1-cyclobutanol)
General rules for drawing Organic compounds: 1. Draw the main chain carbons first, a straight line is the easiest. 2. Attach any functional groups to appropriate positions. (Usually from left to right is easiest) 3. Attach all side chains to appropriate positions. (Determined by your functional group placement) 4. Add in appropriate number of hydrogens. (Recall the HONC rule - each C needs 4 bonds.)
3/08
6
Alkanes H
H
H
Cl H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
H H H HC HHC H H H H HC C C C C H H H H HC H H
H
H H H H H H H H HC C C C C C C C H H H H H H H H HC H H
H C H H H C C C H H H H
CH2CH3
CH3CH2CHCH2CH2CHCH3
CH3 H H
H
H
H
C
C
C
H
H
H
C
CH3 H
H
H
C
C
C
C
H
H
H
H
F
H
Cl
CH3CH2CCH2CHCH2CH3 CH(CH3)2
CH2CH2CH3
CH3 CH3 CH3CH2CH2CCH2CHCH2CH3 CH(CH3)2
3-fluoro-2-methylhexane
4-ethyl-3-methylheptane
Octane
1-bromo-2-methylcyclobutane
2,2,4-trimethylpentane (isooctane)
Octane and 2,2,4-trimethylpentane both have the same formula C8H18 (they are isomers of each other). The difference is that 2,2,4-trimethylpentane is more branched. The branched chained molecules are better for gasoline mixtures. Straight chain molecules ignite too explosively causing “knocking”. Branched molecules burn more smoothly. Isooctane has an octane number of 100 because of its anti-knocking properties. Heptane has an octane rating of 0. It has poor anti-knocking quality. A 95 octane rating would be like having 95% isooctane and 5% heptane. For diesel engines, just the opposite is best. Diesel engines work better on less branched molecules. Diesel engines run on hexadecane, 16-carbon molecules.
3/08
7
Physical properties: Boiling point increases with an increase in molar mass or increase in the number of carbon atoms. Number of C atoms Uses Boiling point 1-4 Natural gas < 30 5-12 Gasoline 30-200 12-16 Jet fuel 200-250 15-18 Diesel 250-350 18-25 Motor oil 350-450 >25 Tar, asphalt Solid, does not boil Boiling point decreases with an increase in branching. Very low solubility in water as they are nonpolar.
Functional Groups Groups of atoms or single atoms can be added to hydrocarbon chains that greatly influence the physical and chemical properties of these molecules. Double and triple bonds are functional groups. Also, many functional groups contain oxygen or nitrogen. Alkenes and Alkynes Importance of Alkenes and Alkynes: Alkenes used to synthesize a wide variety of polymers. Alkynes, especially ethyne is a specialized fuel. Naming: Alkenes and alkynes are named the same way with the longest chain that contains double bond, change ane to ene, triple bond, change ane to yne. The double or triple bond gets the lowest possible number, and is only numbered from the start of the bond Remember, each carbon can only have 4 bonds. These are referred to as unsaturated hydrocarbons. H
H
H
H
C
C
C
H
H
H C
C
H
H
H
H
H
C
C
H
C
C
H
H
H
H H H H
C
H
C
C
H
H
C
CH3 H
H
H
C
C
C
C
H
H
H
H
H H
H
H
C
C
H
H
H C
C
C
H
H
CH2CH3 CH2CHCHCH2CH2CHCH3 CH2CH2CH3
4-methyl-3-heptene 3/08
HC
CH
2-butyne 8
Aromatic Hydrocarbons Importance of aromatic compounds: Aromatic compounds contain a benzene ring. They are very stable compounds and react in many ways. They are found in fuels, biological molecules, plastics, drugs, explosives, foods, flavors, and dyes just to name a few. They tend to have a characteristic odor or aroma, hence the name aromatic. Structure and Naming: Functional Group: Aromatic ring What you need to know: 1) What it looks like: a 6 membered ring with alternating single and double bonds. 2) It is very stable 3) It is unsaturated but the stability allows it to behave as a saturated hydrocarbon. CH3
OH
H C HC
CH
HC
C
C
CH C H
HC
CH
HC
CH
HC
CH
HC
CH C H
C H O
O
OH
H3C
HC
C
C
C
OH
NO2
C H
Acetylsalicylic Acid
CH
HC
H C N
C HC
CH
HC
Salicylic Acid HC
C
CH3
O
CH
CH3
CH
HC
C HC
H C
O
C H
C H
CH
C
O HO
N-Acetyl-para-aminophenol (Tylenol)
Cinnamaldehyde
C CH
H C O
Vanillin CH3
OH
HO HO
CH
C HC
CH3 C CH3
O
CH3
OH OH
Pelargonidin This molecule is responsible for the red color we see in raspberries and strawberries.
3/08
CH C
CH C H
HO
C
HC
OH
C
NO2
C
C
C HC
C
O2N
O
O
C
HC
CH3
O 2-tert-butyl-4-methoxyphenol Also called BHA an antioxidant. Molecules in food cause fat molecules to oxidize or rot or break down into smaller molecules and become rancid. BHA attacks the molecules that oxidize the food before they can attack the food.
9
Alcohols Importance of alcohols: Fermentation: Yeast ferments sugars found in grains like corn and barley or fruits like grapes and apples to produce ethanol. Combustion: In some ways our bodies are like the engines in our cars. Both can combust or burn alcohol to produce carbon dioxide and water and energy. In our bodies the reaction is more complicated but the result is the same Ethanol + Oxygen Æ carbon dioxide + water CH3CH2OH + O2 Æ CO2 + H2O Caloric value: Calories/gram Fat = 9 Alcohol = 7 Carbohydrates = 4 Protein = 4 Ethanol Economics: Structure and Naming: Functional group: -OH General Formula: R-OH Three types of alcohols: H
H
H
OH
C
C
C
H
H
H
hydroxyl group ROH
H
H
1-propanol Primary 1o The hydroxyl (OH) group is attached to a primary or methyl carbon
H
H
H
C
C
C
H
OH H
H
H
2-propanol Secondary 2 o The hydroxyl (OH) group is attached to a secondary carbon
H
CH3H
C
C
H
OH H
C
H
2-methyl-1-propanol Tertiary 3 o The hydroxyl (OH) group is attached to a tertiary carbon
1. Change the name of the longest chain that contains the –OH from ane to ol and number the chain giving the OH the lowest number. H
CH3OH
H
and
H
C
C
H
H
H
H
OH H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
2-propanol 3/08
H
OH
H
H
H
H
H
H
H
H
H
H
OH
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
CH3H
H
CH3H
H
H
C
C
C
C
C
C
H
H
H
OH CH3H
H
C
H
H
CH3
2-methyl-3-pentanol 10
Ethers Importance of ethers They have been used as anesthetics for many years. They are very volatile and explosive. Structure and Naming: Ethers are similar to alcohols in that they contain an oxygen with 2 single bonds. They differ in that the oxygen is not bonded to a hydrogen but to 2 carbons. Functional group: General Formula:
COC R-O-R’
1. Name the longest continuous hydrocarbon chain with its normal alkane name. 2. Change the name of the other, shorter hydrocarbon chain, with the oxygen, from its normal alkane name from ane to oxy. It is treated as a side chain with a number. H H
H
C
O
H
H
C
H
H
H
H
H
C
C
H
H
O
H
H
H
H
H
OH
C
C
C
C
C
C
H
H
H
H
H
H
H
H
C
C
H
H
O
CH3
H
H 3C
C
H
H
H
C
C
C
H
H
H
H
CH3
O
CH3
MTBE fuel additive used to increase oxygen in the fuel for cleaner burning .
2-methoxybutane 3-methyl-2-ethoxy butane Thiols Importance of thiols: These molecules have a very strong odor and are found in perm solutions, foods, coffee and skunks! Structure and Naming: These molecules are similar to alcohols but the oxygen is replaced by a sulfur with 2 bonds Functional group: -SH sulfhydryl General Formula: R-S-H Name the same as alcohols but use the suffix thiol instead of just ol. CH3CH2SH CH3SH Added to natural gas to detect leaks through odor Found in oysters and cheese H
S
H
H
H
C
C
C
H
H
H
H H
Onions O
SH C
C H2
C H
2-furymethanethiol coffee scent. 3/08
S
C
C
C
H
H
H
2-propene-1-thiol Garlic
HC HC
H
H
H
S
H
H
CH3
C
C
C
H
H
H
CH3
3-methylbutane-1-thiol skunk scent 11
Aldehydes Importance of aldehydes: Aldehydes are quite reactive due to the oxygen atom and are used to make many other types of molecules. Vanillin (see below) contains 3 functional groups and is responsible for the flavor of vanilla. Thomas Jefferson introduced this flavor to the United States. Structure and Naming: Aldehydes have a carbon double bonded to an oxygen at the end of a hydrocarbon chain O O Functional group: O C is called the carbonyl group CH CH General Formula: R RCHO Change the name of the longest continuous hydrocarbon chain that has the CHO from ane to al. There is no number since the functional group is always on the end or first carbon. O H O Very toxic. Used to preserve specimens. Ethanol is oxidized in the liver into this H C Kills bacteria. H C C molecule which is somewhat responsible for the “hangover” H H
H
Acetaldehyde
Formaldehyde CH3 O
O C
O H
HO
Benzaldehyde responsible for the flavor of almonds
H
Vanillin (notice 3 functional groups and benzene)
Butanal
2-methylbutanal
Ketones Importance of ketones: Acetone is found in nail polish remover, found in many flavorings O O Structure and Naming: O C Functional group: is called the carbonyl group C C C C R' General Formula: R RCOR 1. Change the ending of the name the longest hydrocarbon chain that contains the carbonyl from ane to one. 2. Number the carbon with the carbonyl so that it has the lowest number. O O Acetone found in nail polish remover. Very flammable. H2 H2
H 3C
C
C
C
CH3
Produced by bacteria. Found in the smell of H 3C C C CH3 armpits and unwashed feet. Butanedione: the flavor of butter and margarine. O
C
CH3
O
2-methyl-3-pentanone 3/08
H 3C
butanone
5-methyl-3-hexanone 12
Carboxylic acids Importance of Carboxylic acids: These are weak acids. The hydrogen in the carboxyl group can ionize a little bit in aqueous solution. They are found in all types of food, giving a sour taste. Structure and Naming: The functional group is a combination of a carbonyl and a hydroxyl or a carboxyl. O Functional group: called a Carboxyl group OH C O General Formula: RCOOH C
R
OH
Esters are named with 2 words 1. Change the ending of the name of the longest chain that contains the carboxyl group from ane to oic acid. There is no number since the carboxyl group is always on the end. (It always starts at position 1) Lactic Acid Found in milk, and Alcohol is oxidized to this and O O that is why cheap wines taste like pickles Responsible for sore H CH CH 3 vinegar. Certain bacteria break OH muscles from heavy activity or H C C O H down the sugar maltose in dough heavy drinking. when OH into acetic acid, giving sour sugars.breakdown. H dough. Acetic acid: found in vinegar. O C
OH
Kills bacteria and is used as a preservative in foods, cosmetics and toothpaste.
CH3CH2COOH
Benzoic Acid Injected by stinging ants Methanoic acid . Also called formic acid.
Pentanoic acid
2-methylhexanoic acid
3/08
13
Esters Importance of esters The food industry relies heavily on esters for the flavoring of food. Many natural flavors are due to esters. Structure and Naming: Esters are similar to carboxylic acids in that they contain 2 oxygens one with a single bond and one with a double bond. They differ in that the functional group is not on the end of the molecule. O
Functional group:
C
O
O
General Formula: RCOOR C O R' R Esters are named with 2 words 1. The 2nd word is made by changing the ending of the name the longest hydrocarbon chain that contains the carbonyl from ane to anoate 2. The 1st word is the alkyl group that is attached to the single bonded oxygen. It is named like a side chain- but there is no number. 3. There is no number since the carboxyl group is always on the end. (It always starts at position 1) O
O H 3C
C
O
CH3
CH3CH2CH2CH2CH2CH2CH2
H
CH3COOCH2CH2CH2CH2CH3. (This is responsible for the flavor of bananas.)
H C H
H H
H
H O
O
C
CH3
H
C C C C C O C H H H H H HC H H
amyl acetate Methyl salicylate: This molecule is responsible for the flavor of O wintergreen. is a mild irritant when rubbed on the skin. This induces a brief and minor O inflammation of the skin which delivers more blood and OH more heat to the skin and subcutaneous regions such as muscles. This is why methyl salicylate is an active ingredient in many liniments.
Recently methyl salicylate has been shown to be an anti-aphrodisiac in moths. During mating, a male moth transfers a sperm packet, which contains sperm and nutrients, into the body of the female. During the next 24 - 48 hours the female will lay eggs which are fertilized by this male's sperm. In order to discourage other males from mating with the female, the sperm packet is also laced with methyl salicylate. It has been observed that other males will approach a recently mated female, but are repelled by the Oil of Wintergreen. It appears that the females do not become attractive again until about 5 days after their first mating. The first male therefore derives a reproductive advantage in having more of his offspring in the next generation.
Propyl ethanoate
Butyl 3-methylpentanoate
H 3C
3/08
14
Amines Importance of amines Amines can accept a hydrogen which makes them weak organic bases. They are an important part of amino acids. They generally smell bad. Structure and Naming: Amines have all single bonds and contain a nitrogen. H Functional group: Called the amino group H
N
H R
N H RNH2 General Formula: 1. Add amino to the name of the longest hydrocarbon chain with the amino group and indicate its position with the smallest possible number. H NH2CH2CH2CH2CH2CH2NH2 Putrescine: The horrible odor from rotting flesh H N CH2CH3
H H H H H H HC C C C C N H H H H H HC H H
H2 C
CH
CH3 H3C
N CH3
Responsible for the odor of rotting fish. When lemon is squeezed onto cooked fish the citric acid in the lemon neutralizes the amine (organic base) and forms a salt getting rid of the fishy taste. Trimethylamine H2 C
CH3
H2 C
H N
CH3
NH2
Amphetamine
Methamphetamine Also called “speed”.
This molecule absorbs UV light HO C NH2 from the sun and is found in sun block. para-aminobenzoic acid Also called PABA O
2-aminopentane
It is both an amine and a carboxylic acid.
Amides Importance of amides Amides are neutral. They are an important part of proteins. Structure and Naming: (you will not name the amides, just recognize the structure, class functional group) O
Amide
Functional group: C
N
O
RCONH2
General Formula: R
H O H N
CH
Methanamide 3/08
C
N
R'
H C
H O H N
CCH3
Ethanamide
O
H N CH2CH3
N-ethylmethanamide 15
Polymers Polymers are enormous molecules made up of repeating units called monomers. “Mer” simply means unit. Just like a train is a long chain of repeating similar train cars hooked together, a polymer is a long chain of similar molecules chemically hooked together. You wear polymers, you drive with polymers, you work with polymers, you chew polymers. They are everywhere. The properties of polymers depends on the individual repeating units and how they are hooked together. Polymers can be “man made” but are also found in nature. Protein is a polymer. Polyethylene is a very common plastic. It is found in bags, plastic wrap and milk bottles. If you have seen the triangle symbol with HDPE, you are using polyethylene. Here is how it is made: H
H C H
Ethene (ethylene) is hooked together: H
H
+
C
C
H
+
C H
H
H
H C
etc. Æ
C H
H
H
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
This chain can be hundreds or thousands of ethene units. The chains can be long and straight like spaghetti or the chains can be “cross linked”. This means that the chains hook up with other chains from the side forming a web-like structure. Common Polymers Name Basic Unit (monomer) Polymer Use H CH H CH3H CH3H CH3 3 Polypropylene Clothing, carpets C C C C C C C C H
H
Polydichloroethylene (Saran) Polytetrafluoroethylene (Teflon) Polyvinyl chloride PVC
H
Cl
C
C
H
Cl
F
F
C
C
H H
H H Cl H
H H Cl H
H Cl
C
C
C
C
C
C
H
Cl H
F
F
F
F
Cl H F
F
C
C
C
C
C
C
F
F
F
F
F
Sandwich wrap
Cl
Non-stick coatings
F
F
H
Cl
H
Cl
H
Cl
H
Cl
H
C
C
C
C
C
C
H
H
H
H
H
H
C
F
C
H
Polystyrene
H C HC HC
C H2C
CH
H C CH
HC
CH
CH
HC
H
H
C
H
H
C
C
C
C
C
C
C
C
H CH
H HC
C
H CH
H
CH
HC
HC HC C H
CH
Hoses, pipes, garbage bags
Coffee cups, insulation, Styrofoam
CH C H
Other common polymers include polyester (an ester) , rubber (a natural hydrocarbon) , chewing gum (a type of rubber), nylon (an amide). 3/08
16
Physical Properties Boiling point: Size: In the same functional group the boiling point increases with increasing molar mass or chain length. methane pentane hexane hexadecane CH4 -161ºC C5H12 +36ºC C6H14 +69ºC C16H36 +287ºC Branching: If two compounds have the same molar mass the one with the least branching will generally have the higher boiling point. 2,5-dimethylhexane 2,2,4octane 2-methylheptane Trimethylpentane CH3CH2CH2CH2CH2`CH2CH2CH3
C8H18
+125 ºC
CH3CHCH2CH2CH2CH2CH3 CH3
C8H18
CH3CHCH2CH2CHCH3 CH3
+119 ºC
C8H18
CH3
+108 ºC
CH3
CH3CCH2CHCH3 CH3
C8H18
CH3
+99 ºC
Functional Group: The more functional groups that are present the higher the boiling point. 1-propanol 1,3-propandiol 1,2,3-propantriol CH3CH2CH2OH + 97 ºC
CH2OHCH2CH2OH +210 ºC
CH2OHCOHCH2OH +290 ºC
The more polar a compound is the higher the boiling point: Use the following trends. Nonpolar Polar H- bond Polar and H-bonds alcohols carboxylic acids Ethers Alkanes amines amides aldehydes Alkenes ketones Alkynes esters Aromatics Lowest boiling Highest boiling Propane –42ºC Propanone / Propanal +46ºC 1-propanol +96ºC Propanoic acid +141ºC Methyl ethanoate +56ºC Propanamide +213ºC Solubilty: Size: In the same functional group the solubility increases with decreasing molar mass or chain length. Functional Group: The more functional groups that are present the higher the solubility. The more polar a compound is the higher the solubilty: Use the following trends. Nonpolar Polar Can H- bond Polar and H-bonds alcohols carboxylic acids Ethers Alkanes amines amides aldehydes Alkenes ketones Alkynes esters Aromatics Least soluble Most soluble ~0 C’s / group ~3 C’s / group ~5 C’s / group ~6 C’s / group Pentane trace 3-pentanone 0.7 g/100mL 1-pentanol 2.7 g/100mL pentanoic acid 5.7 g/100mL 3/08
17
