|Unit 3 Organic Chemistry
|Are You Ready?
Page 176 Answers
|So far we have dealt with the metals and non-metals and
the compounds made up from them. Group 14 on the periodic table. The Carbon
group, was deliberately avoided because of the material involved in ORGANIC
chemistry. All of the inorganic chemicals known worldwide number approximately
50,000 but the number of organic compounds number 500,000 and about 2,000
more are added each year.
|Organic chemistry is the study of compounds made primarily
from carbon. These compounds have unique properties based mainly on the
fact that carbon can bond to itself covalently almost indefinitely. The
most important aspect of the atoms involved in organic chemicals are their
valence bond electrons.
|A quick review is needed. Carbon has four valence electrons
which results in 4 covalent bonds. Hydrogen has only one electron and has
only one covalent bond. Oxygen has 6 valence electrons but 4 are bound
up in two lone pairs leaving only 2 single bonding electrons. Nitrogen
has 5 valence electrons but 2 are bound in a lone pair leaving 3 covalent
bond electrons. Most of the other elements follow this same general rule.
- C - H- -N -O- -S- Cl- Br-
Activity 3.1 Testing Fats and Oils
Hydrocarbons are the simplest of all the organic molcules. They consist of only carbon and hydrogen, hence the term hydrocarbon. The very simplest of all the hydrocarbons is methane.
|It can be shown in one of three ways.
|Each type of formula has its own benefits. Molecular
formulas show what is in a compound but very little about how the atoms
are put together. The structural formula shows the position of each atom
and its relationship to every other atom, but it is time consuming to write
out. The skeletal equation shows all covalent bonds, and all atoms except
|Organic chemistry uses certain prefixes that indicate
the number of carbon atoms in a particular molecule. You should
memorize these if you have not already done so.
|There are of course more but these will be sufficient for this course.|
|Using methane, CH4, as a starting point we can add more carbons, one at a time, and more hydrogens to fill out the bonds on the carbons. This first group is called the alkane series and it has the general formula:|
|Look at the list very carefully. Each successive
compound increases by only CH2. Also the molecular weight increases
by only 14.03, that is CH2. It also seems that as
the length of the carbon chain increases from 1 to 11 the melting point
increases as well as the boiling point.
|All of the above are straight-chain alkanes. That is,
each additional carbon is added to the end to form one long continuous
chain and there are only single bonds in the main chain of the molecule.
|Propane has three carbons in a main chain, hence, prop,
and there are only single bonds in this main chain therefore (ane). Octane
has eight C's in a main chain hence, oct, and again the main chain has
only single bonds between beach carbon therefore it is an "ane". Both of
the above are members of the alkane series. Draw several more to verify
for yourself how these compounds are put together.
|IUPAC Rules For Naming Organic Compounds.
(International Union of Pure and Applied Chemists)
|1. Find the longest continuous carbon chain. Count the
number of carbons in it and determine the prefix.
|2. Check to make sure that all the bonds in this long
chain are single. The ending will be "ane"
|3. Put the prefix and ending together.
|Naming compounds with side chains|
|How do we name something like this?|
|First find the longest carbon chain. It has 11 carbons
in it therefore this compound is a "undec" something. Check to see if
it contains only single bonds. It does, therefore it is an "ane" as well.
The compound is a "undecane". What about the C-C group?
|Two carbons is "eth" and it has single bonds therefore
it is ethane but it is attached to the longer chain. Take the "ane" off
and add "yl". This is an ethyl group. If you count bonds it is not C2H6
but it is in fact C2H5-. The "-" indicates
the point of attachment to the long undecane chain. So this compound is
ethylundecane. But where is the "ethyl" group attached. Start counting from
the end of the undecane. The ethyl group is either 5 from one end or 6
from the other end. When this happens always choose the lowest number. So
we can name this as 5-ethylundecane. That is, an 11 carbon alkane called
undecane with an ethyl group stuck on it at the 5th carbon from
|IUPAC Rules For Naming Branched Compounds|
|1. Determine the longest continuous chain, this will
be the parent chain. Give the parent chain a prefix matching the number
of carbon's in it.
|2. Assign #'s to each C of the parent chain so that the
numbers of all attached side pieces add up to the smallest sum.
|3. Determine the correct name for each branch or other
atom or group.
|4. Attach the name of the alkyl group or other substituent
to the name of the parent as a prefix. Place the location # in front and
separate from the name by a hyphen.
|Parent chain is 7 carbons long with all single bonds,
therefore heptane. Side group is one carbon, therefore "meth" and because
it is attached to the parent we add "yl" so we get methyl. The methyl group
is attached to the parent chain at carbon number 3 not carbon number 5.
Count for yourself. Put it all together 3-methylheptane.
|5. When 2 or more groups are attached, name each, and
locate them by number. Always use hyphens to separate the #'s from each
|Ethyl comes before methyl alphabetically, it just happens
to come that way numerically in this example as well.
|In this example ethyl still comes first alphabetically
before methyl. The numbers that locate their point of attachment go with
|6. When 2 or more of the substituents are identical, use special prefixes such as "di" for 2, "tri" for three and "tetra" for 4 and specify the location #'s of every group. eg.|
|7. When identical groups are on the same carbon in the
parent chain, repeat the number on the parent
|Add-on Substitution Groups
The following are substitution groups that can be added on to a main parent chain.
|In addition to the above there are the halogen
F is fluoro
Cl is chloro
Br is bromo
and I is iodo
Go to Organic Worksheet #1 - Simple Chain Nomenclature
|An alkene is simply a C=C, that is a double bond between
two carbon atoms. The position of the double bond will often determine
what is the parent chain. If a double bond exists then the parent chain
must include it. The double bond also uses up 2 bonds that normally hold
hydrogen so the general formula for alkenes is CnH2n.
The double bond also locks the molecule in a certain position so that attached
groups can't rotate around the double bond. This means some special naming
conventions. Easy stuff first:
Butene CH2=CH-CH2-CH3 or CH3-CH=CH-CH3
|There are two structural formulas for butene. This is
because the double bond can come between the 1st and 2nd
C or between the 2nd and 3rd carbon. We get around
this by naming the position of the "ene". You'll also have noticed that the
names have changed from "ane" to "ene" indicating the presence of a double
|These two are isomers. They have the same molecular formula, C4H8, but different structural formulas. We also have a new problem.|
|The cis means (same side) and the CH3- methyl groups are both above the C=C bond and on the same
side (top). Trans means transverse and the CH3-
methyl groups are in a trans position to each other across the C=C bond.
|Some more examples:
|The longest chain of carbons is 7. Therefore this is
a "hept" molecule. There is also a C=C double bond therefore it is a heptene.
Counting from both ends the double bond starts at either 3 or 4. Choose
the lowest number. The molecule is now hept-3-ene. The longest chain is
also split around the C=C bond in a transverse fashion therefore it is
|This accounts for everything about the parent chain.
Since we choose the C=C number to be 3 we have now locked in place a numbering
system for this molecule. That means there is a methyl group at carbon
4. The name of the molecule is therefore: 4-methyl-trans-hept-3-ene.
|Look for the longest continuous carbon chain. There are
9 carbons therefore it is a "nona" and there is a C=C at carbon 4 therefore
it is non-4-ene. The sides of the chain of the parent are both on the same
side. In this case, on top of the double bond therefore it is cis-non-4-ene.
There is a methyl group at carbon 4 and an ethyl group at carbon 5. Therefore
the full name is 5-ethyl-4-methyl-cis-non-4-ene.
Go to Organic Alkene Series Worksheet
Cyclic Alkanes (Cycloalkanes)
|When does an alkane act like an alkene?|
|When its cyclic! Some alkanes circle around and join up with themselves. They lose two hydrogens when they join up and so cyclic alkanes have the same general formula as alkenes (CnH2n).|
|What would iso-propyl-cyclopentane look like?|
|The parent ring will be 5 C's and 10 H's. Then pick any of the C's and remove a hydrogen and replace it with an isopropyl group.|
|Cyclic compounds can also have cis and trans configurations
because things can stick up or down below the equator of the molecule.
Go to Organic Cycloalkanes Worksheet
|The alkyne series is very similar to the alkane and alkene
series. They all have at least one triple bond. Please note the fact that
a single letter change results in a dramatic change in the structure of
Ethyne C2H2 Propyne C3H4
|And the pattern continues just as it did for the alkanes
and alkenes. The general formula of an alkyne is CnH2n-2.
The triple bond prevents rotation but it also prevents the formation if
cis and trans structures in the parent chain.
|In the event a parent chain has both an alkyne and an
alkene the alkyne is more important.
|8 carbons long therefore an "oct". Has both alkene and
an alkyne bonds. The alkyne is the most important therefore number so
that it has the lowest possible number. Therefore we now have "3-yne"
and an alkene at 5 and at 7. Therefore the full name would be oct-5,7-diene-3-yne.
|All the other rules previously learned still apply.
Go to Organic Alkenes and Akynes Nomenclature Worksheet
Extension Exercise 3.1 Naming and Drawing Hydrocarbons
Extension Exercise 3.1 Condensed Structural Fotmulas
Isomers have the same chemical formula but different structure. The more carbon atoms in a formula the more isomeric structures that are possible.
Activity 3.3 Building Molecular Models
Extension Exercise 3.2 Identifying Isomers
Combustion is a reaction with oxygen which produces heat as a result. Hydrocarbons react with oxygen to produce carbon dioxide and water as products as well as heat. The hydrocarbon that burns is referred to as a fuel.
fuel + oxygen -----> water vapor + carbon dioxide
When there is not enough oxygen present, water still gets created but carbon canonly grab one oxygen aton resulting in carbon monoxide. Carbon monoxide is a clear, colorless, odourless gas which is a toxic poison.
fuel + inadequate oxygen -----> water vapor + carbon monoxide
|1. Halogenation with light:
This is a substitution reaction:
R-H + halogen ----------->
R-F, R-Cl or R-Br +
HF, HCl or HBr (R can be any alkane)
|Reactions of the Alkenes and Alkynes|
|When a substitution is made across a C=C or triple bond the H will be added to the carbon that already has the most H's on it. When a dehydration occurs across a C=C or triple bond then the H removed will be from the C that has the most H's on it.|
| 3. Addition of Hydrogen
This is an addition or saturation reaction.
Read Page 193 - 196
Questions Section 3.3 Page 1 through 6
Activity 3.3 The Great Marble Race
Extension Exercise 3.3 A Fractionation Tower
Self Quiz 3.1 - 3.3
Investigation 3.4 Separating A Mixture by Distillation
|Common Functional Groups - Alcohols|
|The alcohol functional group is an -OH. The polar oxygen gives the molecule properties of solubility with other polar solvents such as water. It's polar properties also cause the molecules to stick together by electrostatic attraction more readily. Ethane is a gas at room temperature whereas ethanol (ethyl alcohol) is a liquid at room temperature.|
|eg. CH3CH2OH ethanol (ethyl alcohol).|
|The parent name is kept and the "e" from ethane was dropped
and replaced by "ol". Alcohols are more important than double or triple
bonds. If both an alcohol and a double and/or triple bond appear in a molecule
then name it as an alcohol. If something more important than alcohol is
in a molecule the alcohol gets named as "hydroxy" and a number just like
any other attached group.
Go to the Organic Alcohols Worksheet
Demonstration 3.5 Bending Liquids
Extension Exercise 3.5 Functional Groups
Self Quiz 3.4 - 3.6
Extension Exercise 3.7 Comparing Alcohols and Ethers
Extension Exercise 3.7 Naming and Drawing Alcohols
Investigation 3.8 Properties of Alcohols
-O- found only in the interior of two longer chains.
eg. CH3CH2-O-CH3 ethyl methyl ether or methoxy ethane
CH3CH2-O-CH2CH3 diethyl ether or ethoxy ethane
Aldehydes - short form -COH or
|Aldehydes can only be found on the very end of a molecule
at the primary carbon. If you take a close look three of the four bonds
on the aldehydes carbon are taken up with the oxygen and the hydrogen. Therefore
there is only one bond left for bonding with another carbon and therefore
it must be primary.
Extension Exercise 3.9 Naming and Drawing Aldehydes
|example CH3CH3COH propanal or propyl aldehyde|
Be careful about spelling since a simple letter change results in a vastly different molecule. If the aldehyde is not important the group name changes to 'al' with the # of the appropriate parent chain carbon.
|Why? As you can see only 2 of the carbon's bonds are
used by attachment to the oxygen. Two bonds are available for bonding and
to be a ketone these two must be attached to a carbon on each side, hence
it must be inside a molecule. But what if one of these bonds is attached
to a H? Then its an aldehyde and not a ketone.
The ending "one" is added to the alkane name prefix. If the ketone is not important it's name switches to 'keto' and is treated just like any other substitution group. The ketone is more important than an alcohol and an aldehyde.
Go to Organic Aldehydes and Ketones Worksheet
Extension Exercise 3.9 More Functional Groups
Extension Exercise 3.9 Naming and Drawing Ketones
|Safe Use of Solvents
Read pages 215 - 217
Questions Page 217 1 through 4
Alternative Exercise 3.10 Safety on the Job
Carboxylic Acid propanoic acid
|The -COOH group can only exist at the end of a molecule
for the same reasons as those of the aldehydes. The root parent name of
the above was propane and the "e" is dropped and "oic acid" is added. If
you have two -COOH groups in a molecule you have a "dioic acid". There is
a three carboxylic acid molecule known. It is known as citric acid in citrus
Extension Exercise 3.11 Naming and Drawing Carboxylic Acids
Activity 3.11 Making Aspirin
Investigation 3.12 Properties of Carboxylic Acids
Self Quiz 3.7 - 3.12
Esters can only be found in the interiors of a molecule. An ester is made by dehydration of a water molecule from between an alcohol and a carboxylic acid. When naming the ester molecule the alcohol portion is named first.
|eg. methyl ethanoate|
|Methyl methanoate is made by reacting methyl alcohol
or methanol with methanoic acid (old name formic acid). The alcohol label
is dropped and the "ic acid" is replaced by "ate". The names are not joined
indicating they came from two separate starting molecules.
Examples of some of the more common esters are:
|ethyl formate||C3H6O2||Fruity, rum-like|
|ethyl acetate||C4H8O2||wine, brandy|
|ethyl butyrate||C6H12O2||buttery, fruity|
|ethyl valerate (ethyl pentanoate)||C7H14O2||apple|
|ethyl hexanoate||C8H16O2||apple, banana, pineapple|
|ethyl octanate||C10H20O2||cognac, apricot|
|ethyl decanoate||C12H24O2||cognac, nutty|
|methyl propionate||C4H8O2||rum / black current|
|methyl butyrate||C5H10O2||apple, banana|
3.13 Naming and Drawing Esters
Extension Exercise 3.13 Artificial Flavours
Activity 3.14 Synthesis of Esters
|Amide eg . propamide|
|Amides are found in many biological compounds. They are
a major part of amino acids (proteins) and urea (urine).
|Amine -NH2 without an "O" The
key to these compounds is to remember that the N atom has three possible
bonds. There are three types of amines based upon these bonding patterns.
They are named depending upon the carbon to which they are attached.
|Macromolecules have molecular masses in the thousands.
Each macromolecule is made up of single monomers which are then joined
repeatedly over and over. The joining together of smaller units (monomers)
into very large molecules is called polymerization.
|Nylon 6,6 is made from two molecules "adipyl chloride
and hexadiamine" Nylon is called nylon 6,6 because they join at the
6th carbon in each molecule.
|If you look closely you can see the alternating units
of 6 carbons, and a nitrogen, repeating endlessly.
|Saran is made up the the monomer 1,1-dichloro-ethane
1,1-dichloro-ethane The polymer is below and is called "Saran"
|vinyl chloride becomes polyvinyl chloride(PVC)
|Acrylnitrile becomes polyacrylnitril (Orlon)
|Styrene becomes polystyrene a high impact plastic used
|methyl methacrylate (an ester) becomes polymethyl
methacrylate or "plexiglass"
|Dacron, a polyester is made from two monomer units.
methyl terephthalate and ethylene glycol and forms the polyester "Dacron"
|Unit 3 Summary
Unit 3 Review Page 256 - 257 Questions 1 - 17
Unit 3 Self Quiz