Download - Unit A: Organic Chemistry
• This PowerPoint is available on the Plone Site.• It is your responsibility to print off the notes
that you would like. • You will not be able to write everything down
in class as this will inhibit the time we have to spend on practicing concepts and performing labs.
Unit A: Organic Chemistry
Assessment
Homework will be taken in randomly Even though homework may not be taken in every
day, this does not mean you are not required to complete it fully. This is a 30-level course and the expectation is that you keep up with practicing concepts daily as we will continue to move forward each day.
3 Quizzes will be given throughout the unit You should use these to your advantage as they
test smaller sections of the curriculum and help prepare you for the Unit Exam
Labs – one formal Stations Lab to be handed in Unit Exam – test format will be given to you
later
Unit A: Chapters 9 and 10
Organic
ChemistryToday’s Objectives:
1)Define organic compounds as compounds containing carbon, recognizing inorganic exceptions such as carbonates, cyanides and carbides
2)Identify and describe significant organic compounds in daily life, demonstrating generalized knowledge of their origins and applications
3)STS: Demonstrate an understanding that science and technology are developed to meet societal needs and expand human capability
Section 9.1 (pg. 354-361)
Organic Introduction
Today’s Agenda:
1)Introduce organic chemistry and review the origins and applications of some major organic compounds
2)“Carbon – The element of life” video
What is Organic Chemistry?
The early definition related to compounds obtained only from living things.
Today, it is a major branch of chemistry that deals with compounds of carbon, called ORGANIC compounds*. *Carbon compounds that are exceptions and
considered INORGANIC are compounds like: Oxides carbon monoxide (CO(g) ) and carbon dioxide (CO2(g) ),
and Ionic compounds of carbon-based ions, such as
carbonate CO32-, cyanide CN-, and carbide ions, SiC (silicon
carbide)
The major source of carbon compounds is still living or previously living things, such as plants, animals and all types of fossil fuels.
Organic or Inorganic??
Formula Organic or Inorganic?
CaCO3(s) Inorganic (carbonate ion)
C25H52(s) Organic
Ca2C(s) Inorganic (carbide ion)
CCl4(l) Organic
CH3COOH(l) Organic
CO2(g) Inorganic (oxide)
KCN(s) Inorganic (cyanide)
C12H22O11(s) Organic
Why is carbon special?
There are millions or organic compounds and only a thousand inorganic compounds. WHY? Carbon has a bonding capacity of 4
Remember Lewis Dot Diagrams from Chem 20?? This means carbon can bond extensively and can
bond together to form chains effectively = called Polymerism
Carbon covalently bonds by sharing 4 pairs of electrons. These bonds may be single, double or triple, all producing stable compounds
Compounds can form with same number of each type of atom but different structures = Isomerism
So why do we care about bonding capacity? If we know how many bonding e-’s an atom has, we can
predict what structure a molecular compound will have
Determining Lewis Formulas
Atom Number ofvalence electrons
Number ofbonding electrons
Bonding capacity
carbon 4 4 4
nitrogen 5 3 3
oxygen 6 2 2
halogens 7 1 1
hydrogen 1 1 1H
I.e. Carbon can form 4 single bonds, 2 double bonds, 1 triple and 1 single, or 1 double and 2 singles
Polymers
Examples of repeating carbon chains:
Isomers
Compounds with the same number of each type of atom but different structures (C4H10)
We will talk about this in more detail later
Importance of Organic Chemistry
Building units of all living matter: carbohydrates, proteins, fats All foods are organic compounds Photosynthesis is a reaction that makes carbon a part of our
food. Carbon is passed along through food chains and sugar from photosynthesis is modified and combined with other materials.
Dead organisms are food for other organisms, or are buried in the earth and converted to fossil fuels like peat, coal and petroleum
Petroleum is the source of fuel and starting material for plastics, fabrics and industrial chemicals
The carbon cycle is an illustration of the interrelationship of all living things with the environment and with technologies that refine and use fossil fuels
We will continually outline the importance of organic compounds in our daily lives
Carbon: The Element of LifeComplete the worksheet provided as you watch the following video (20 min)
Today’s homework
Ensure video worksheet is complete and in your notes to review later
Work on Are you Ready pg. 354-355 # 1- 6 – due tomorrow
What is coming up tomorrow? Naming alkanes, branched
alkanes and cycloalkanes
Section 9.2 (pg. 366-374)
Naming Organic Compounds
Today’s Objectives:1)Name and draw structural, condensed structural, and line diagrams and formulas for saturated and unsaturated aliphatic (including cyclic)
• Containing up to 10 carbon atoms in the parent chain/cyclic structure
• Containing only one type of a functional group or multiple bond
• Using the IUPAC nomenclature guidelines
2)Identify types of compounds from the functional groups, given the structural formula
3)Define structural isomerism and relate to variations in properties
Four Types of Formulas
1. Molecular Formulas C5H12(g) Not very
useful for organic compounds because so many isomers can exist
2. Structural Formulas
1. Condensed Structural Formulas
2. Line Diagrams
– end of line segment represents carbon
– it is assumed to satisfy each carbon’s octet
Naming Organic Compounds
Aliphatic Hydrocarbons – contains only hydrogen and carbon atoms Straight line chains of carbon atoms Alicyclic hydrocarbons have carbon atoms forming a
closed ring. Still considered aliphaticAlkanes Alkenes Alkynes
Only single C-C bonds
Double C-C Bond present
Triple C-C bond present
General formula CnH2n+2
General formula: CnH2n
General formula:CnH2n-2
Saturated Unsaturated Unsaturated
In organic chemistry, names have a root and a suffix. The root describes the
number of carbons present in the chain or ring.
The suffix describes the type of compound it is.
Naming Organic Compounds
Naming Organic Compounds
Naming ALKANES
1. Find the parent chain (the longest continuous chain of carbon atoms). Use the appropriate root and the suffix-ane.
Naming ALKANES
1. Find the parent chain. Use the appropriate root and suffix.
2. Number the carbon atoms, starting from the end closest to the branch(es) so that the numbers are the lowest possible
3. Identify any branches and their location number on the parent chain (us the suffix –yl for branches)
4. Write the complete IUPAC name, following the format: (number of location, if necessary) – (branch name) (parent chain)
2-methylheptane
If more than one of the same branch exist, use a multiplier to show this (di, tri). Remember to include all numbers
Draw 2,4,6-trimethylheptane
Naming ALKANES
If different branches exist, name them in alphabetical order
ethyl before methyl (e before m in the alphabet)
Naming ALKANES
If there is more than one branch of the same type, a locating number is given to each branch and a prefix indicating the number of that type of branch is attached to the name.
This numbering prefix does not affect the alphabetical order of the branches
Draw the structural formula for 3,4-dimethylhexane
Naming ALKANES
Summary of Naming Alkanes
1. Find the parent chain. Use the appropriate root and suffix.
2. Number the parent chain carbon atoms, starting from the end closest to the branch(es) so that the numbers are the lowest possible
3. Identify any branches and their location number on the parent chain (us the suffix –yl for branches)
4. If more than one of the same branch exist, use a multiplier (di, tri) to show this. Remember to include all numbers
5. If different branches exist, name them in alphabetical order
6. Separate numbers from numbers using commas, and numbers from words using dashes (no extra spaces)
Don’t forget
Questions will specifically ask about structural, condensed structural or line structural formulas.
You must be comfortable drawing any of the three
Practice
Write the IUPAC name for the following
2,5-dimethyl-4-propyloctane
Correct the following names: 4-ethyl-2-methylpentane
ACTUALLY 2,4-dimethylhexane ALWAYS LOOK FOR LONGEST CHAIN!!
Correct the following name: 4,5-dimethylhexane
Actually 2,3-dimethylhexane **Want branch numbers to be as low as
possible
CYCLOALKANES
Based on evidence, chemists believe that organic carbon compounds sometimes take the form of cyclic hydrocarbons:
Cycloalkanes: Alkanes that form a closed ring General Formula CnH2n
Two less hydrogens are present than in straight chain alkanes because the two ends of the molecule are joined
Are these considered saturated?? Yes, because they have only single bonds and the max amount of hydrogen's bonded to the carbons
Cyclo-compounds will have a higher boiling point than their straight chain partners (because there is an additional bond present)
Cycloalkanes are named by placing the prefix cyclo in front of the alkane name, as in cyclopropane and cyclobutane
If branches are present, treat the cycloalkane as the parent chain and identify the branches.
Since there is no end at which to start the numbering, use the lowest numbers possible
Naming CYCLOALKANES
Name the following:
1. 2.
1,2-dimethylcyclopentane ethylcyclohexane
**Why don’t we need a number?
Today’s homework
HW Book page 1 – check over as a class Pg. 370 #7 (a-c) ,9(a-c), 10 (a-b) 11 (a-
c) Pg. 372 #5-6 (Extra)
What is coming up tomorrow? Naming Alkenes, Alkynes, Cycloalkenes
and Cycloalkynes Comparing properties of Isomers
Section 9.3 (pg. 374-380)
Naming Organic Compounds:
Alkenes and AlkynesToday’s Objectives:1)Name and draw structural, condensed structural, and line diagrams and formulas for saturated and unsaturated aliphatic (including cyclic
• Containing up to 10 carbon atoms in the parent chain/cyclic structure
• Containing only one type of a functional group or multiple bond
• Using the IUPAC nomenclature guidelines
2)Identify types of compounds from the functional groups, given the structural formula
3)Define structural isomerism and relate to variations in properties
Review:
Find and name all of the isomers of pentane (C5H12(l))
Structural Isomerism
Compound with the same molecular formula but different structures They will have different chemical and
physical properties – based on their different structures
Alkenes and Alkynes
Alkenes – hydrocarbons containing a double C-C bond General formula (CnH2n) - (like cycloalkanes)
Alkynes – hydrocarbons containing a triple C-C bond General formula (CnH2n-2) – (like cycloalkenes)
Alkenes and Alkynes are considered unsaturated compounds. They do not have the maximum number of hydrogen atoms surrounding each carbon.
Reactivity: Alkynes (highest), Alkenes, Alkanes (lowest)
Naming Alkenes and Alkynes
1. Find the parent chain. It MUST contain the multiple bond.
If the bond is a double, the suffix for the parent chain will be -ene
If the bond is a triple, the suffix for the parent chain will be –yne
2. Count carbon atoms so that the multiple bond will be on the lowest possible number. Indicate the number that the multiple bond falls on directly before the suffix
3. Name branches as before
Naming Alkenes and Alkynes
Draw the following as condensed structural formulas:
4-methylpent-2-yne
methylpropene(why don’t we need a number?)
Naming Alkenes and Alkynes
Name the following:
3-methylbut-1-ene
5-methylhex-2-ene
Naming Alkenes and Alkynes
4. It is possible for a molecule to have more than one double bond. These are called alkadienes and have the same general formula as alkynes (CnH2n-2)
If this is the case, indicate both numbers where the double bond is formed, and change the suffix to –diene.
a) Draw buta-1,3-diene:
b) What is the IUPAC name for the following:
buta-1,2-diene
Cycloalkenes and -ynes
The rules for naming cycloalkenes and cycloalkynes are the same as naming cycloalkanes The numbering for the carbon atoms begins
with the double bond; the carbons of the double bond are carbons 1 and 2; lowest numbers possible
Draw 3-methylcyclohexene as a condensed structural
formula
Today’s homework
HW Book page 2 – go through as a class Pg. 377 #1-5 Pg. 380 #6 (a-b) , 7 (a-b), 11 (a-b) Due tomorrow /22 marks
What is coming up tomorrow? Hydrocarbon Quiz #1 (MON) Naming Aromatics Boiling point and Chemical Properties
Analysis
Section 9.4 (pg. 381-385)
Naming Organic Compounds:
AromaticsToday’s Objectives:
1)Name and draw structural, condensed structural, and line diagrams and formulas for aromatic carbon compounds
• Using the IUPAC nomenclature guidelines
2)Identify types of compounds from the functional groups, given the structural formula
3)Define structural isomerism and relate to variations in properties
Hydrocarbon Quiz #1
Aromatics
Originally, organic compounds with an aroma or odour were called aromatic compounds
Now, aromatics refer to compounds containing a benzene-ring structure Benzene’s formula is C6H6, which would suggest a
highly unsaturated and reactive compound Benzene is actually quite unreactive and is
considered more stable than alkenes and alkynes Did You Know?? Benzene is a carcinogen and is
found naturally in petroleum – why would this be a problem?
What do we know about benzene? Formula is C6H6 (3D link) Unreactive – so no true double or triple
bonds Carbon-carbon bonds are the same length
and strength Each carbon is bonded to a hydrogen So what does benzene look like??
The three double bonds resonate resulting in an overall bond length somewhere in
between a single and a double bond, explaining benzene’s stability
We will use this line structural
formula to represent
benzene in compounds
Common Aromatic Compounds
Include Aspirin and Vanillin (one of the flavour molecules in vanilla) You will notice many aromatic molecules are often
depicted using a condensed structural formula except for the benzene ring, which is shown as a line structural formula.
This combination is commonly used by chemists, and we will use this method when drawing aromatics.
Naming Aromatics
1. If an alkyl branch is attached to a benzene ring, the compound is named as an alkylbenzene.
Alternatively, the benzene ring may be considered as a branch of a large molecule: in this case, the benzene ring is called a phenyl branch. Which has a phenyl branch?
An alkylbenzene Contains a phenyl branch
Naming Aromatics
2. If more than one alkyl branch is attached to a benzene ring, the branches are numbered using the lowest numbers possible, starting with one of the branches.
Given the choice between two sets of lowest numbers, choose the set that is in both numerical and alphabetical order
1-ethyl-2,4-dimethylbenzene 3-phenyl-4-propyloctane
Practice Naming Aromatics
Draw 1,2-dimethylbenzene Are there any isomers of this compound?
There is also classical way of naming these isomers. The arrangements are denoted by the prefixe:s ortho (o), meta (m) and para (p). These names are still used in industry so you may encounter them in other references.
1,2-dimethylbenzen
e
1,3-dimethylbenzen
e
1,4-dimethylbenzen
e o-dimethylbenzen
e
m-dimethylbenzen
e
p-dimethylbenzen
e
Practice Naming Aromatics
Draw the line structural formula for 1-ethyl-3-methylbenzene
Draw the line structural formula for 2-phenylpentane
Practice Naming Aromatics Draw 3-phenylpent-2-ene
Name the following propylbenzene
Why is no number needed?
Are the hydrogen’s wrong??
Summary
We have now learned about both aliphatic and aromatic hydrocarbons. You will need to be comfortable naming all of the following:
Teacher Note:
End if not enough time for two dry labs Can use during the Station Lab Periods
Review of Intermolecular Forces London Forces – temporary dipoles resulting
from an uneven distribution of e- in all molecules Temporary (-) end will repel e- in neighbouring
molecules and so on Depends on size of molecule (number of e-’s) Weakest of the intermolecular forces
Dipole-Dipole – only exists in polar molecules Attraction between + and – ends of molecule
Hydrogen Bonding – super strong force Only exists when H-N, H-F, H-O bonds are present
Applications Read pg. 384 Lab Exercise 9.A – complete the parts in red
Purpose: To test the generalization that aromatic hydrocarbons react like saturated rather than unsaturated hydrocarbons
Design: cyclohexane, cyclohexene and benzene are all mixed with potassium permanganate (purple). Evidence for a reaction is a change in the initial purple colour of the solution.
Prediction: Based on your current knowledge, predict the order in which the compounds will react, from least reactive to most reactive. Explain your reasoning.
Analysis: On the basis of the evidence, determine the order of the reaction rate for the three compounds.
Evaluation: Determine if your prediction was verified or falsified. Was the generalization about aromatic hydrocarbons acceptable based on the evidence? Was the purpose of the investigation accomplished?
Sample lab report for 9.A
Applications Read pg. 384 Lab Exercise 9.B – complete the parts in red
Purpose: To test the ability of the concept of London forces to predict the relative boiling points of aliphatic and aromatic compounds (Remember: the more electrons in a compound = the stronger
the intermolecular forces = the higher the boiling point needed to pull the molecules apart)
Problem: What is the relative order of the boiling points of hexane, hex-1-ene, cyclohexane, cyclohexene, and benzene?
Prediction: Determine the number of electrons in each molecule and use these numbers to determine the order of boiling points
Analysis: On the basis of the evidence given, determine the order of the boiling points. (from lowest to highest)
Evaluation: Determine if your prediction was verified or falsified. Was the predictive power of the concept of London forces judged to be acceptable based on the evidence? Was the purpose of the investigation accomplished?
Extra Practice for Lab Reports Complete pg. 355 #6
Complete the prediction, analysis and evaluation
Remember lab report guidelines in textbook starting on pg. 790
Today’s homework
Pg. 385 #3-5 – due tomorrow
What is coming up tomorrow? Review Aromatic and Aliphatic
Compounds
Section 10.2 and 10.3 (pg. 417-435)
Organic Chemistry:Organic Halides and
Alcohols Today’s Objectives:
1)Name and draw structural, condensed structural and line diagrams and formulas for organic halides and alcohols
2)Identify types of compounds from their functional groups, given the structural formula and name of the functional groups
Today’s Agenda: Review
You will have another Hydrocarbon Quiz next class covering all aliphatic and aromatic compounds
Today’s agenda: Review Quiz – go over common
mistakes Homework Book page 3 and 4 Pg. 380 #6 (c-e), 7 (c-e) Pg. 385 #6-8
**7d) 4-methyl (not 3-methyl) Make the change in your book if not
done already
Aliphatic and Aromatic Compounds
Hydrocarbon Quiz #2
Review of Intermolecular Forces London Forces – temporary dipoles resulting
from an uneven distribution of e- in all molecules Temporary (-) end will repel e- in neighbouring
molecules and so on Depends on size of molecule (number of e-’s) Weakest of the intermolecular forces
Dipole-Dipole – only exists in polar molecules Attraction between + and – ends of molecule
Hydrogen Bonding – super strong force Only exists when H-N, H-F, H-O bonds are present
Organic Halides
Organic compounds where one or more hydrogen has been replaced with halogens (F, Cl, Br, I) Common example: CFC (chlorofluorocarbons)
Nomenclature is similar to naming branch chains of hydrocarbons, but the branch name used is based on the halogen used chloro-, fluoro-, bromo-, iodo-
Organic Halides
What do you need to know about organic halides? May by polar or nonpolar molecules or may have a
relatively nonpolar (hydrocarbon) end and a polar (halide) end (**Remember Electronegativity differences)
Have higher boiling points than similar hydrocarbons Have very low solubility in water but higher
solubility than similar hydrocarbons Are typically good solvents for organic materials
such as fats, oils, waxes, gums, resins or rubber Usually toxic or ecologically damaging (DDTs and
PCBs)
Practice Naming Organic Halides
Draw 1,2-dichloroethane
Draw 2,2,5-tribromo-5-methylhexane
Practice Naming Organic Halides
Name the following: CH2Cl2
1,2-dibromoethene
Bonus: Try 1,2-dibromo-1,2-dichloroethene
chlorobenzene
dichloromethane
Did You Know?
There is always a new concept to learn that extends what you have already learned.
In addition to the structural isomers that you know about, there are cis and trans isomers
Stop and Practice
Homework Book pg. 5 and 6
Alcohols
An alcohol is an organic compound that contains the –OH functional group (hydroxyl) General formula is R-OH (R = rest of molecule)
Alcohols are classified as primary, secondary or tertiary depending on the number of carbons bonded to the carbon that contains the hydroxyl group
Common Alcohols
Methanol (also called wood alcohol) is extremely toxic, causing death and blindness
Ethanol (also known as grain alcohol) is the alcohol found in alcoholic beverages and is used in the production of vinegar
Gas line antifreeze, windshield de-icer, windshield washerfluid – all containmethanol
Naming Alcohols
1. Locate the longest chain that contains an –OH group attached to one of the carbon atoms. Name the parent alkane
2. Replace the –e at the end of the name of the parent alkane with –ol (i.e. butane becomes butanol)
3. Add a position number before the suffix –ol to indicate the location of the –OH group
REMEMBER to number the main chain of the hydrocarbon so that the hydroxyl group has the lowest possible position number
propan-1-ol
Naming Alcohols
4. If there is more than one –OH group (called polyalcohols), leave the –e in the name of the parent alkane and put the appropriate prefix before the suffix –ol (i.e. diol, triol, tetraol)
4. Name and number any branches on the main chain. Add the names of these branches to the prefix.
Draw 2,3-dimethylbutan-2-ol
Practice Naming Alcohols
Draw line structural formulas for:
1. cyclohexanol
2. phenol
1. The three isomers of C5H11OH that are pentanols
These are the only two cyclic or aromatic alcohols you will need to
know as they get very complicated
Alcohols
What do you need to know about alcohols?Question: Why is the propane used in a barbecue a gas at room temperature, but propan-2-ol (also known as rubbing alcohol) a liquid at room temperature?
Answer: Propane is a non-polar hydrocarbon with weak intermolecular forces, thus it has a low boiling point and is a gas at room temperature.
Propan-2-ol is an alcohol, with a polar hydroxyl group and strong intermolecular forces, thus it has a higher boiling point than propane and is a liquid at room temperature
Alcohols
What do you need to know about alcohols?Question: Glycerol (propane-1,2,3-triol) is more viscous than water, and can lower the freezing point of water. When added to biological samples, it helps to keep the tissues from freezing, thereby reducing damage. From your knowledge of the molecular structure of glycerol, suggest reasons to account for these properties of glycerol.
Answer: Each molecule of glycerol contains three hydroxyl groups which can hydrogen-bond with water, interfering with the attractions between water molecules and thus interfering with the freezing of water. When water in tissues does not freeze, there is less damage to the tissues.
Application Question
Predict the order of increasing boiling points for the following compounds, and give reasons for your answer.
butan-1-ol pentane 1-chlorobutane
Answer: (Lowest b.p.): pentane, 1-chlorobutane, butan-1-ol
Why? All molecules have a similar number of electrons. Pentane has the lowest boiling point, because it is non-polar so will only have London forces between the molecules. 1-chlorobutane is polar so will have dipole-dipole forces as well as London forces. Butan-1-ol has the highest boiling point because its molecules will have all three intermolecular forces, most importantly, hydrogen bonding
Today’s homework
Homework Book pg. 5 and 6 Pg. 419 #3 Pg. 430 #5,6,7a,9a
Due tomorrow
What is coming up tomorrow? Carboxylic Acids and Esters
Section 10.4 (pg. 436-443)
Organic Chemistry:Carboxylic Acids and
EstersToday’s Objectives:
1)Name and draw structural, condensed structural and line diagrams and formulas for carboxylic acids and esters
2)Identify types of compounds from their functional groups, given the structural formula and name of the functional groups
Carboxylic Acids
A carboxyl group is composed of a carbon atom double bonded to an oxygen atom and bonded to a hydroxyl group (-COOH) Note: Because the carboxyl group involves
three of the carbon atom’s four bonds, the carboxyl is always at the end of a carbon chain or branch
methanoic acid ethanoic acid
Examples:
Carboxylic acids are weak organic
acids
Naming Carboxylic Acids
1. Name the parent alkane
2. Replace the –e at the end of the name of than parent alkane with –oic acid
3. The carbon atoms of the carboxyl group is always given position number 1. Name and number the branches that are attached to the compound.
Draw 3-methylbutanoic acid
HOOC
Remember COOH or HOOC can also
represent the carboxyl group
Naming Carboxylic Acids
1. Draw trichloroethanoic acid (key ingredient in chemical peels)
CCl3COOH
2. Draw 3-propyloctanoic acidDo you need the CH3 here? No – but sometimes you will see it written this way. Don’t be confused because it doesn’t change the meaning
Esters
The reaction between a carboxylic acid and an alcohol produces an ester molecule and a molecule of water This reaction is known as a condensation or esterification
reaction
The ester functional group –COO– is similar to that of a carboxylic acid, except that the H atom of the carboxyl group has been replaced by a hydrocarbon branch.
Esters are responsible for natural and artificial fragrance and flavourings in plants and fruits.
In naming an ester you have to recognize that an ester has 2 distinct parts. The main part contains the C=O group which comes from the parent acid. The second part is the alkyl group.
Esters
Naming Esters
1. Identify the main part of the ester, which contains the C=O group. This part comes from the parent acid.
2. Begin by naming the parent acid but replace the –oic acid ending of the name with –oate. (propanoic acid becomes propanoate)
3. The second part is the alkyl group that is attached to the single oxygen atom. Name this as you would any other alkyl group (in this case = methyl)
4. Put the names together. Note that esters are named as two words.
Naming Esters
Name the following ester and the acid and alcohol from which it can be prepared.
ethyl butanoate
ethanol
butanoic acid
water
Tip: The branch attached to the oxygen (of the –COO) comes first in the name, the chain attached to the carbon (of the –COO) comes second
A strong acid catalyst, such as H2SO4(aq) is used along with some
heating to increase the rate of the
organic reaction
Naming Esters
Name the following ester and the acid and alcohol from which it can be prepared.
ethyl benzoate
ethanol
benzoic acid
water
What is missing from this esterification reaction?
Today’s homework
Pg. 438 #1,2 Pg. 441 #3-5 Homework Pg. 8 (All Organic Compounds)
Due tomorrow
What is coming up tomorrow? Physical Properties of Organic
Compounds Crude Oil Refining Full Naming Quiz (tomorrow)
Section 9.5 and 9.6 (pg. 386-400)
Properties of Organic Compounds & Crude Oil
RefiningToday’s Objectives:
1)Compare boiling points and solubility of organic compounds
2)Describe fractional distillation and solvent extraction
3)Describe major reactions for producing energy and economically important compounds from fossil fuels
Physical Properties of Simple Hydrocarbons
Alkanes Non-polar moleculesOnly intermolecular forces are London ForceBoiling point and melting point increase with number of carbonsAll insoluble in water (like dissolves like) – nonpolar and polar don’t mix1-4Cs = gas, 5-16Cs = liquid 17 and up = solid at SATP
Alkenes Non-polar molecules, therefore insoluble in waterBoiling points slightly lower than alkanes with the same number of carbons due to less electrons (unsaturated), resulting in lower London Forces
Alkynes Non-polar molecules, therefore insoluble in waterHigher boiling points than alkanes and alkenes with similar C #sAccepted explanation: Linear structure around triple bond allows electrons to come closer together than in alkanes/enes, resulting in greater London Force
Branching
The more branching, the less significant the London Force (~lower b.p.) - more surface area in straight chain hydrocarbons allows more separation of charge, resulting in greater London Force - see Table #3 pg. 378 (i.e. pentane (with 5Cs) has a b.p. of 36oC which is much higher than dimethylpropane (5Cs) -12oC) = because branching decreased the strength of the London force
Physical Properties of Hydrocarbon Derivatives
Alcohols Much higher boiling points than hydrocarbons (1-12Cs are liquids at SATP) due to hydrogen bonding between hydroxyl groups of adjacent moleculesSmall alcohols are totally miscible in water, but the larger the hydrocarbon part of the alcohol (nonpolar part), the more nonpolar the alcohol is
Carboxylic Acids
Like alcohols they have hydrogen bonding, but is more significant due to the C=O. This means greater bps and solubility than alcohols with same number of Cs.
Carboxylic acids with 1-4Cs arecompletely miscible in water
Esters Fruity odour in some casesPolar but they lack the –OH bond therefore do not have hydrogen bonding, so lower bps than both alcohols and carboxylic acidsEsters with few carbons are polar enough to be soluble in water
Compound Boiling Point (oC)
butane -0.5
butan-1-ol 117.2
butanoic acid
165.5
Summary Table - OrganicIn your homework book (pg. 7), there is a summary table of all of the organic compounds we have studied. This will be a good page to reference when studying
Sample Question
Predict the relative order of boiling points of the following compounds (lowest to highest). Explain your reasoning.
butanol but-1-ene cyclobutane butanoic acid butane
Lowest -------------------------------------------------------------> Highest
but-1-ene butane cyclobutane butanol butanoic acid
Reasoning: but-1-ene has lower LF’s for than butane because it is unsaturated, cyclobutane has an additional bond because cyclic, butanol has H-bonding, butanoic acid has stronger H-bonding)
Which would be soluble in water? Butanol and butanoic acid – because they are the only polar
molecules and like dissolves like!
Crude Oil Refining
Crude oil is a complex mixture of hundreds of thousands of compounds, all of which have different boiling points We can take advantage of these different b.p.’s
and physically separate the different components using heat
This process is called fractional distillation or fractionation
A fractional distillation tower contains trays positioned at various levels.
Heated crude oil enters near the bottom of the tower.
The bottom is kept hot, and the temperature gradually decreases toward the top of the tower.
As compounds cool to their boiling point, they condense in the cooler trays. The streams of liquid (called fractions) are withdrawn from the tower at various heights along the tower.
Electronic Visual
A more detailed look… The vaporized components of the
crude oil rise and gradually cool.
To get from one level to the next, the vapours are forced to bubble through the liquid condensed in each tray.
The figure shows the bubble caps used to allow this to happen.
If a gas cools to its boiling point, it will condense and be piped out through the draining tube Q: How does the number of carbon atoms in a
hydrocarbon chain affect its boiling point? Smaller molecules have fewer electrons, so weaker
London forces compared with larger molecules. The fractions with higher boiling points are found to contain much larger molecules (see Table 1 pg. 387)
Crude oil is heated in the fractionation tower without air being present to reduce the risk of mixtures starting
to burn or explode
Cracking
Cracking: large hydrocarbons are broken into smaller fragments
Historically, thermal cracking used extremely high temperatures but created large quantities of solid coke.
Now, catalytic cracking uses a catalyst to speed up the reaction and produce less residual products like tar, asphalt and coke Example: C17H36(l) C9H20(l) + C8H16(l) + C(s)
larger molecules smaller molecules + carbon
In 1960, hydrocracking was developed, which combines catalytic cracking and hydrogenation and produces no coke. Example: C17H36(l) + H2(g) C9H20(l) + C8H16(l)
larger molecule + hydrogen smaller molecules
Oil Refining
The refining of crude oil can be divided into two main categories:
1. Physical Processes Fractional Distillation: see previous slides Solvent Extraction: solvent is added to selectively dissolve and
remove an impurity or to separate a useful product from a mixture
2. Chemical Processes Cracking – larger molecules are broken down into smaller ones Reforming – large molecules are formed from smaller ones These chemical processes are needed because fractional distillation
does not produce enough of the hydrocarbons that are in demand (i.e. gasoline) and produces too much of the heavier fractions
Catalytic Reforming and Alkylation
Catalytic Reforming: improves the quality of the gasoline
aliphatic molecule aromatic molecule + hydrogen
Alkylation: increases the branching; improves the quality of the fuel
aliphatic molecule more branched molecule (AKA: isomerization because it converts molecules into a
branched isomer)FYI pg. 392 on
Octane Numbers
Combustion Reactions
Burning of hydrocarbons in the presence of oxygen Complete Combustion: abundant supply of oxygen;
products are carbon dioxide, water vapour and heat Ex. C3H8(l) + 5O2(g) 3CO2(g) + 4H2O(g)
Incomplete Combustion: limited supply of oxygen; products are carbon monoxide, soot (pure carbon) or any combination of carbon dioxide, carbon monoxide and soot in addition to water vapour and heat Ex. 2C8H18(l) + 17O2(g) 16CO(g) + 18H2O(g)
OR 2C8H18(l) + 9O2(g) 16C(s) + 18H2O(g)
** Assume complete combustion unless specified otherwise
Balancing FYI
Ex. 2C8H18(l) + 17O2(g) 16CO(g) + 18H2O(g)
Can also be balanced using a fraction (you need to be
comfortable using this method) – divide each number by 2
C8H18(l) + 17/2 O2(g) 8CO(g) + 9H2O(g)
Ex. 2C8H18(l) + 9O2(g) 16C(s) + 18H2O(g)
can also be balanced as …
C8H18(l) + 9/2 O2(g) 8C(s) + 9H2O(g)
Today’s homework
Read pages 410-416 Pg. 388 #2 Pg. 391 #11 Pg. 397 #4 b, c, d only Pg. 430 #11
What is coming up tomorrow? Hydrocarbon Quiz #3 (all organic
compounds) Use Homework Book pg. 8 as practice quiz
Hydrocarbon Reactions Addition, Substitution and Elimination
Section 10.2,10.3 and 10.4 (pg. 419-444)
Hydrocarbon Reactions:Addition, Substitution and
EliminationToday’s Objectives:
1)Define, illustrate and provide examples of simple addition, substituion, elimination and esterification (condensation)
2)Predict products and write and interpret balanced equations for the above reations
All Organic Compounds
Hydrocarbon Quiz #3
Hydrocarbon Reactions
1. Addition alkenes and alkynes + H2(g) alkanes (hydrogenation)alkenes and alkynes + HX (or X2) organic halides
2. Substitutionalkanes and aromatics + X2 organic halides
Eliminationalcohols alkenes + water (dehydration)
organic halides + OH- alkenes + halide ion + water
Esterification (already covered) carboxylic acid + alcohol ester + water
1. Addition Reactions: reaction of alkenes and alkynes with hydrogen gas, a halogen compound, or a hydrogen halide compound.
Addition reactions usually occur in the presence of a catalyst
a) Addition with H2(g) (also called hydrogenation)
1. Addition Reactions: reaction of alkenes and alkynes with hydrogen gas, a halogen compound, or a hydrogen halide compound
b) Addition of a halogen
Since addition reactions involving multiple bonds are
very rapid, the alkene product 1,2-
dibromoethene can easily undergo a
second addition step to produce 1,1,2,2-
tetrabromomethane.
Excess bromine promotes this second
step.
1,2-dichloroethane is a useful solvent and is
used to produce chloroethene, the monomer used to
make PVC.See Pg. 417 equation
1. Addition Reactions: reaction of alkenes and alkynes with hydrogen gas, a halogen compound, or a hydrogen halide compound
c) Addition of an HX (hydrogen halide) molecule Show both possible isomers when predicting the
products
The addition of hydrogen halides (HF, HCl, HBr or HI) to unsaturated compounds can produce structural
isomers, since the hydrogen halide molecules can add in different orientations. However, the type of isomers
produced are not always equal.
For example only a tiny amount of 1-chloropropane is produced compared to 2-chloropropane in the above
reaction.
Practice Addition Reactions
For each of the following questions, draw condensed structural diagrams and name all products
1. ethene + bromine
2. hydrogen chloride + ethene
3. 3-methylbut-1-yne + excess hydrogen
1,2-dibromoethane
chloroethane
__2-
methylbutane
2. Substitution Reactions – breaking of a C-H bond in an alkane or an aromatic ring and replacing it with another atom or group of atoms
Usually occur slowly at room temperature, so light may be necessary as a catalyst
Often substitutes a halogen for a hydrogen No change in saturation
Propane contains hydrogen atoms bonded to end carbons and the middle carbon atom, so two different products (isomers)
are formed, in unequal proportions
2. Substitution Reactions – breaking of a C-H bond in an alkane or an aromatic ring and replacing it with another atom or group of atoms
Benzene rings are stable, like alkanes, so they react slowly with halogens, even in the presence of light.
As with alkanes, further substitution can occur in benzene rings, until all hydrogen atoms are replaced by halogen atoms
(in the presence of excess halogens)
Would all three isomers be created equally?
NO
Practice Substitution Reactions
For each of the following questions, draw condensed structural diagrams and name all products
1. propane + fluorine
2. ethane + chlorine
1-fluoropropane + 2-fluoropropane + hydrogen
fluoride
chloroethane + hydrogen chloride
H - FF - F
3. Elimination Reactions – involves eliminating atoms or groups of atoms from adjacent carbon atoms; decreases the level of saturation
3. Alkane cracked into an alkene (uses high temperatures)
4. Alcohol is reacted with a catalyst to produce an alkene and water (dehydration – removes a water molecule from the alcohol)
a) Alkyl halide reacts with a hydroxide ion (OH-) to produce an alkene (dehydrohalogenation – removes a hydrogen and halogen atom)
Practice Elimination Reactions
Write a structural formula equation for the preparation of but-2-ene from chlorobutane, in the presence of a strong base
Write a structural formula equation for the preparation of but-2-ene from butan-2-ol
Reaction type
Complete Combustion
Addition Elimination Substitution Esteri-fication
Reactants Hydrocarbon* + O2
ene or yne + HOH, X2, HX, or H2
alcohol or alkyl halide
alkane or aromatic + X2
alcohol + carboxylic acid
Products CO2(g) + H2O(g) or (l)
alcohol, alkyl halide*, alkane
alkene + HOH or HX
alkyl halide ester + water
Other triple or double to single
single to double
slow; needs uv light
acid catalyst needed
Other more bonds*
fewer bonds*
Today’s homework
Homework Book Pg. 9 Pg. 422 #7,8 (Addition and Substitution) Pg. 433 #18-19 (Elimination)
What is coming up tomorrow? Polymerization STS Connections
Section 10.5 (pg. 445-459)
Organic Chemistry: Polymerization Reactions
Today’s Objectives:
1)Define, illustrate, and give examples of monomers, polymers, and polymerization in living and non-living systems
STS: 2) Illustrate how science and technology are developed to meet societal needs and expand human capabilities
STS: 3) Illustrate how science and technology have both intended and unintended consequences
Polymerization
Polymers are large molecules made of chains of monomers, small molecules that link together. Polymerization is the formation of
polymers from these small units
Polymers can occur naturally (proteins, carbohydrates) and can be synthesized (nylon, Teflon, polyethylene)
They play an integral part in the function of life systems and have revolutionized the way society functions
Addition Polymerization
Many plastics (synthetic polymers) are made by this process
The polymerization process is initiated with a free radical (a species with an unpaired electron). The free radical attacks and breaks the double bond forming a new free radical that attacks another monomer
Addition Polymerization always results in one product, the polymer
Requires unsaturated hydrocarbon monomers and bond saturation occurs when the polymer is made
Common polymers produced by addition polymerization:
Things to know about addition
polymers…
The polymer names end in –ene (i.e. polystyrene, polypropene). Does this mean they have double bonds? No, the double bonds are saturated by adjacent monomers,
as the polymer is made. The name refers to the starting monomer (i.e. polyethene is started by the monomer ethene)
What properties make Teflon a good product for non-stick materials? Teflon is made up of C-F bonds which are very strong (not C-H
bonds). These very strong bonds make the Teflon highly unreactive (non-sticking), it has a high melting point and it has a slippery surface
Condensation Polymerization Monomers combine to form a polymer and a bi-
product. Each time a bond forms between monomers, small molecules, such as water, ammonia, or HCl are “condensed” out.
The polymerization of nylon:• For condensation
polymerization to occur, monomers must be bifunctional, meaning they have at least two functional groups.
• If they only had one functional group, then only one bond would form.
Condensation Polymerization Condensation polymerization also produces
natural polymers, called proteins. Amino acids (monomers) polymerize to make
peptides (short chains of amino acids) or proteins (long chains of amino acids)
Comparison of Addition and Condensation Polymerization
Needs a double or triple bond in the monomer
Produces only one product, the polymer
Needs bifunctional monomers (have two functional groups)
Produces two products: the polymer and the biproduct (water, ammonia or HCl)
Addition Condensation
Polyester When a carboxylic acid reacts with an alcohol in an
esterification reaction, a water molecule is eliminated and a single ester molecule is formed.
This esterification reaction can be repeated so many esters are joined in a long chain… a polyester This is created using a dicarboxylic acid (an acid with a
carboxyl group at each end) and a diol (an alcohol with a hydroxyl group at each end)
The ester linkages are formed end to end between alternating acid and alcohol molecules
Polyester: Dacron
Another example of a polyester: Note the two carboxyl groups in the
dicarboxylic acid and the two hydroxyl groups in the polyalcohol that start the chain reaction
Natural Polymer Examples
Starch, wood, silk, DNA
Today’s homework
Make Your Own Polymer Pg. 448 #2-4 Pg. 452 #13 Pg. 455 #16, 17
Due tomorrow
What is coming up tomorrow? Esters Lab
Chemistry 30 Organic Review
Unit Exam
Learning Tip Pg. 441