C C C

C H

H

H

H

HH

H H H H H

H H H H H

Organic Chemistry

1. Organic Chemistry

- Organic chemistry is the study of carbon compounds.

- The properties of organic compounds are determined by two factors:i. A molecular skeleton called a hydrocarbon. This is a series of carbon atoms

linked together to form a stable framework that is almost completely unreactive. The unbonded electron positions are then filled (saturated) with hydrogen atoms.

ii. A series of different reactive groups, called functional groups, can then be added. They determined the basic “chemistry” of the molecule.

- Carbon atoms have unique properties that allow them to make many compounds:i. Carbon atoms can form four bonds ( C )

ii. They link together with covalent bonds to form chains and rings of different sizes,

Electron dot formula structural formula

iii. They form single, double and triple covalent bonds.

- Hydrocarbons tend to have some unique properties that are determined by their covalent bonds:

i. Hydrocarbons are easily decomposed by heat.ii. Hydrocarbons reactions are generally slow.

iii. Most hydrocarbons are insoluble in water. Their molecules are nonpolar and are not attracted to the polar water molecules.

2. Alkanes

a) Continuous –Chain Alkanes- The simplest hydrocarbons are the alkanes that contain only hydrogen and carbon atoms with atoms with single covalent bonds.

2 + 6

- The formula for and alkane can be given several ways: C5H12 (molecular formula)

1) H-C – C – C – C – C – H (complete structural formula)

2) CH3-CH2-CH2-CH2-CH3 (condensed structural formula or semi-structural)

1

C C C

C C C C C C C C C

H C C

3) C-C-C-C-C (skeletal structural formula)

4) (line structural formula)

- The simplest alkanes form a chain. The first ten compounds in this homologous series are to be memorized:

1 CH4 Methane2 C2H6 Ethane3 C3H8 Propane4 C4H10 Butane5 C5H12 Pentane6 C6H14 Hexane7 C7H16 Heptane8 C8H18 Octane9 C9H20 Nonane10 C10H22 Decane

Note: i. The names for the alkanes end in “-ane”.

ii. The general formula for alkanes is CnH2n+2

b) Branched – Chain Alkanes

- Sometimes and atom or group of atoms can replace a hydrogen atom in an alkane. The added atom is called a substituent.

CH3-CH2-CH3 CH3-CH(Br)-CH3

If the substituent is another hydrocarbon, it is called and alkyl group.

CH3-CH2-CH3 CH3-CH(CH3)-CH3

An alkyl group (methyl) joined to the parent chain (propane)

-When an alkyl group is attached to a parent chain, it creates a branched-chain alkane.The names of the alkyl groups are based on its alkane name but ending in “yl”.Examples:

Methyl (-CH3)Ethyl (-CH2-CH3) or (-C2H5)Propyl (-CH2-CH2-CH3) or (-C3H7)

Note: i. An alkyl group cannot exist by itself; it must be attached to some molecule.

ii. The general formula for alkyl groups is CnH2n+1

Example: CH3-CH2-CH-CH2-CH3

2

CH2

CH2-CH3

This shows an ethyl group attached to a heptane molecule.

The formula can also be given as CH3-CH2-CH(C2H5)-CH2-CH2-CH3

Nomenclature for Branched-Chain Alkanes

1. For One Branch1. Find the longest chain and name it.2. Number the carbons in order to locate the alkyl group. (Begin from the end that

gives the branch the lower number).3. The alkyl group name is placed in front of the parent chain name.4. The number must be separated from the name with a hyphen.

Example: CH3-CH2-CH2 - longest chain = hexane

CH-CH2-CH3 - branch name = methyl

CH3 - branch location = 3rd atom

NAME: = 3 - methylhexane

2. For More Than One Branch- Each branch is again located on the main chain.- The branch names are listed alphabetically.- Prefixes are used if an alkyl group appears more than once.

Example: CH3-CH2-CH2 - longest chain = octane

CH-CH3 - branches = methyl at 4 and 5= ethyl at 4

CH3-C-CH2-CH3

CH2-CH2-CH3

NAME: = 4,5-dimethyl, 4-ethyl- octaneNote:

i. Branches can be identified in condensed formulas by placing them in brackets. From the previous example (4-ethyl-4,5-dimethyloctane) CH3-CH2-CH2-CH(CH3)-C(CH3)(C2H5)-CH2-CH2-CH3

ii. Don’t forget: Count from the end that gives the lowest numbers

2c) Structural Isomers

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- It is possible to draw the structures of two or more hydrocarbons that have the same molecular formula but different structural formulas. These compounds are called structural isomers.

C4H10

CH3-CH2-CH2-CH3 CH3-CH(CH3)-CH3

butane 2-methylpropane

- Isomers will only be a different chemical only if they can be given a different name.- Isomers have different chemical and physical properties.

Try This: 1. How many structural isomers are possible for each of the first five straight-chain

alkanes.2. Give the condensed structural formula and name for

a) all of the isomers for C5H12

b) the five isomers of C6H14

3. Optional Challenge – Name all 18 isomers of C8H18.

3. Alkenes and Alkynes

- Remember that carbon can also form multiple bonds. Hydrocarbons containing a double bond are called alkenes

( C=C ).

- Alkenes are unsaturated hydrocarbons because they contain fewer hydrogen atoms. These atoms were removed in order to create the double bond.

- The other unsaturated hydrocarbon is the alkyne which contains a triple bond ( -CC- ).

Nomenclature: 1. Find the longest chain containing the multiple bonds (Its name will now end in “-

ene” or “-yne”).2. The main chain must now be numbered to give the multiple bonds the lowest

number (instead of the branched chains). This number will be used in front of the name of the main chain.CH3-CH=C(CH3)-CH(CH3)-CH3 (3,4-dimethyl-2-pentene)CH3-CH2-CH(C2H5)-CCH (3-ethyl-1-pentyne)

Note: i. The general formula for an alkene is CnH2n and for an alkyne is CnH2n-2.

ii. The physical properties of the unsaturated substances are similar to those of the alkanes.

iii. The most important difference in chemical properties is that multiple bonds are quite reactive.

Try This: Name or provide the structural formula for these compounds:i. CH3-C(CH3)=CH-CH(CH3)-CH3

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CH3

CH2CH3

ii. CH3-CH2-CH(C2H5 )-CCHiii. 5,6-dimethyl-2-octyneiv. 2-methyl-1-propene

Summary

Number of C

Name of the

prefix for

Hydrocarbons molecule alkane

CnH2n + 2

Hydrocarbons molecule alkene

CnH2n

Hydrocarbons molecule alkyne

CnH2n -2

1 Meth CH4 nil nil2 Eth C2H6 C2H4 C2H2

3 Prop C3H8 C3H6 C3H4

4 But C4H10 C4H8 C4H6

5 Pent C5H12 C5H10 C5H8

6 Hex C6H14 C6H12 C6H10

7 Hept C7H16 C7H14 C7H12

8 Oct C8H18 C8H16 C8H14

9 Non C9H20 C9H18 C9H16

10 Dec C10H22 C10H20 C10H18

4. Cycloalkanes (Geometric Shapes)

- In some alkanes, the two ends of the chain have attached to form a ring. These are called cycloalkanes.

Examples:1) cyclobutane 2) cyclohexane

H2C – CH2 H2

CH2C – CH2

H2C CH2

or orH2C CH2

CH2

Note: i. Cyclohexanes have only single bonds and that there general formula is CnH2n.

Cycloalkenes and cycloalcynes also exist.ii. Cycloalkanes have strained bonds that lead to a less stable molecule than its

equivalent alkane.Nomenclature: The ring carbons are numbered so as to give the substituents the lowest possible number (One substituent will always be 1).

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H3C

CH3

HC

HC

CH

CH

CH

CH

HC CH

CH

CH

HC CH

CH3

H3C H3C H3CCH3

CH3

CH3

1,3-dimethylcyclooctane 1-ethyl-2-methylcyclopropane

Try This: Give the structural formula for these compounds.a) 1-ethylcyclobutaneb) 1,3-dimethylcyclopentanec) 1,1-dimethylcyclopropaned) cyclopropylcyclohexane (!)

5) Benzene

- The most important group of cyclic hydrocarbons is the aromatic compounds, the simplest of which is benzene (C6H6). After benzene forms a ring, each carbon atom has one extra electron that is free to make half of a double bond.

The benzene ring can be shown as or

Resonance occurs when two valid structures can be drawn for the same molecule. Resonance is the result of the combination of blending of the two possible structures. The actual substance is an average of all the possible arrangements.Molecules that exhibit resonance are very stable.

Nomenclature: 1) One substituent Added: or C6H5(CH3)

(branch) Methylbenzene (or toluene)

2) When Used as a Substituent – named phenyl (-C6H5) *(CnHn-1)CH3-CH-CH2-CH3 or CH3-CH(C6H5)-CH2-CH3

2-phenylbutane3) Two Substituent Added (note the positions)

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1,2-dimethylbenzene 1,3-dimethylbenzene 1,4-dimethylbenzene or or oro-dimethylbenzene m-dimethylbenzene p-dimethylbenzene(“ortho” position) (“meta” position) (“para” position)

Note: that one Substituent must be in the “l” position.

6 a) Fractional Distillation

Directions: Use the key words and phrases with its matching step in the diagram to give a step-by-step explanation of the fractional distillation of oil.

Towera) Crude oil, fraction, alkanesb) Heater, 350oC, boiling point, vaporizingc) Bubble cap, rising gases, condensation, trays

Fractions1. Residue, (tars, asphalt), highest boiling point (400oC), C30

2. Lubricants and waxes, 3500C, approximately C20 – C30

3. Heating/diesel oil, 250oC, C16 – C20

4. Kerosene, 180oC, approximately C12 – C16

5. Gasoline, 110oC, approximately C5 – C12

6. Natural gases, lowest boiling points, C1 – C4, LPG

6 b) Hydrocarbon Reaction

1. Cracking

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Large fractions form the fractionation process is chemically broken with heat and a catalyst to produce more valuable fuel hydrocarbons with 5-12 carbon atoms per molecule. Large molecule small moleculesExample: C17H36 C8H18 + C9H18

alkane alkene

2. ReformingThis is the opposite of cracking. It can convert low-grade gasolines into higher grades with the use of heat and a catalyst. Small molecules large molecule Example: 2 C5H12(l) C10H22(l) + H2(g)

3. CombustionMost hydrocarbons are used as fuels (95%).Hydrocarbon + O2(g) CO2(g) +18H2O(g) + heatExample: 2C8H18 + 25O2 16CO2 + 18H2O + heat

4. HydrogenationThis process converts unsaturated hydrocarbons to saturated ones.Alkene + H2(g) alkaneAlkyne + H2(g) alkeneExample: CH2=CH-CH2-CH3(g) + H2(g) CH3-CH2-CH2-CH3(g)

1-butene butane

Try This:1. Identify and complete each reaction. You must not break the Law (of

Conservation of Matter)a) C14H30 into octane b) ethane into octane c) 1-octene into octane d) 1-octyne into octane

2. Show the complete combustion of: a) pentane b) hexane c) hexene

7. Functional Groups

- The hydrocarbon skeleton of an organic molecule is chemically inert. Most organic chemistry, then, involves the atoms and molecules that are attached to this main chain.

a) Structures - Functional groups are the atoms in an organic compound that have been added to a hydrocarbon chain. They are the only part of the molecule that is capable of reacting chemically.- Compounds are classified according to their functional groups. Since these groups can be attached to any chain, we will represent the inert hydrocarbon chain with “R”.

Family Name Condensed Formula Example (3C’s) General Formula

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1. Halocarbons R(X) CH3-CH2-CH2(Cl) CnH2n+1X

2. Alcohols R(OH) CH3-CH2-CH2(OH) CnH2n+2O

3. Ethers R1 – O – R2 CH3-O-CH2-CH3 CnH2n+2O

4. Aldehydes R – C(=O)H CH3-CH2-C(=O)H CnH2nO

Ketones R1 – C(=O) – R2 CH3-C(=O)-CH3 CnH2nO

5. Carboxylic acids R – C(=O)(OH) CH3-CH2-C(=O)(OH) CnH2nO2

6. Esters R1 – C(=O) – O – R2 CH3-C(=O)-O-CH3 CnH2nO2

7. Polymers ( - R1 – R2 - )n (-CH2-CH2-CH2-)n

Questions:1. Why does oxygen have to bond twice in a molecule?2. How many times would these atoms bond? a) S b) Cl c) N d) F e) P 3. Which families cannot be made from methane?4. Do any groups have the same general formula?

b) Two Physical Properties

- The presence of a functional group has a major effect on the physical properties of a compound. Intermolecular forces determine many physical properties, such as solubility and boiling point:

- hydrocarbons – have only weak dispersion forces.- functional groups – may have strong hydrogen bonds.

- Remember that hydrogen bonds are created between two molecules:- One molecule contains a hydrogen atom bonded to a highly electronegative

atom (especially oxygen). These hydrogen atoms now can be considered to be a naked proton (+).

- The other molecule will be polar with a - section (especially on oxygen).

The hydrogen bonding, then, occurs between two highly polar molecules.

- Boiling Points: Compounds with hydrogen bonding have higher than expected boiling points: at SATP, C2H6 = gas but CH3OH = liquid.

- Solubilities: Compounds with hydrogen bonds are usually soluble in water (a polar molecule): C6H14 = insoluble in water but C5H11OH = soluble in water.

Solubility decreases, as the molecule gets longer. (C12H25OH =slightly soluble in water).This is because the hydrogen bonding –OH group has less effect on the larger molecule.

8. 1. Halocarbons (R – X)

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- Halocarbons are produced by the substitution of a halogen (Family VIIA) for hydrogen in the hydrocarbon chain;

Cl = chloro Br = bromo I = Iodo F = Fluoroas well as NO2 = nitro NH2 = amino

Nomenclature: The halocarbon is treated as a substituent. Don’t forget that substituents are named alphabetically.CH3-C(Br)(CH3)-CH3 2-bromo-2-methypropaneCH3-CH(Cl)-C(NO2)(C2H5)-CH2-CH3 2-chloro-3-ethyl-3-nitropentane

Try This: Name or provide the formula for the following:a) CH3-CH2(I) f) trichloromethaneb) CH2(Cl)-CH2(Cl) g) 2-chloro-3-iodo-1-butenec) CH(F)(F)-CH(Cl)(Cl) h) 1,5-dinitro-2-pentyned) CH3-CH2-CC-CH2(NH2) i) 1,3-difluorocyclopentanee) CH3-CH(NO2)-CH2(Br) j) 1,3-dibromo-3-phenylhexane

Reactions:a) Addition Reactions – A halogen (X) is added to an unsaturated hydrocarbon at the

double/triple bond. These reactions are quite rapid because there are no strong covalent bonds to be broken. R1 = R2 + X2 RX – RX

Ethyne + chlorine gas 1,2-dichlorethaneCHCH + Cl2 CH(Cl)=CH(Cl) which can be further reacted

CH(Cl)=CH(Cl) + Cl2 CH(Cl)(Cl)-CH(Cl)(Cl)

b) Substitution Reactions – A halogen replaces hydrogen in a saturated hydrocarbon. These reactions occur quite slowly at room temperature because C – H bonds are quite stable. R – H + X2 R – X + HX

Ethane + chlorine chloroethane + hydrogen chlorideC2H6 + Cl2 C2H5Cl + HCl

More complicated molecules will form isomers.CH2(Cl)-CH2-CH2-CH3 + HCl

CH3-CH2-CH2-CH3 + Cl2

CH3-CH(Cl)-CH2-CH3 + HCl

c) Elimination Reactions – This is the most common method for preparing alkenes. A halocarbon reacts with a hydroxide to produce an alkene.

R – R – X + OH- R = R + H2O + X-

CH3-CH(Br)-CH3 + NaOH CH2 = CH-CH3 + H2O + NaBr

9. 2. Alcohols

- Alcohols contain the hydroxyl (-OH) group: R – O – H

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OH

Nomenclatrue: Add “-ol” to the stem of the name of the parent chain. Number the position of the hydroxyl group.If more than one –OH group is present, use these endings:

- “-diol” (two hydroxyls)- “-triol” (three hydroxyls)

Examples: CH3-CH(OH)-CH3 2-propanolCH3-CH(CH3)-CH2-CH2(OH)3-methyl-1-butanolCH2(OH)-CH2-CH(OH)-CH3 1,3-butandiol

Phenols are alcohols in which the –OH group is attached to benzene.

[C6H5(OH)]

Try This: Name or give the formulas for the following: 1. CH3CH(OH)-CH3 5. 2-pentanol2. CH2(Cl)-CH(OH)-CH3 6. 2,2,4-pentatriol3. CH2(OH)-CH2(OH)-CH2-CH3 7. 3-ethyl-2-pentanol4. C6H4(OH)(CH3) 8. 2-ethylphenol

Reactions: 1. MAKING ALCOHOLS

i. Fermentation – producing ethanol from sugars by the action of yeast.C6H12O6(aq) 2CH3CH2OH(aq) + 2CO2(g)

ii. Substitution – the halogen in a halocarbon is replaced by a hydroxide.R – X + M – OH R – OH + MX

CH3-CH2(Cl) + NaOH CH3-CH2(OH) + NaCl

iii. Addition – a water molecule (H-OH) is combined with an unsaturated hydrocarbon.R1 = R2 + H – OH R(OH) \

CH2=CH2 + H-OH CH3-CH2(OH)

2. REACTING ALCOHOLS i. Elimination – Alcohols can be used to make alkenes when catalyzed by

concentrated sulfuric acid acid

R – OH R1 = R2 + H – OHCH3-CH2(OH) CH2=CH2 + H2O

Properties: Alcohols tend to have high boiling points due to the strong hydrogen bonding that occurs between these molecules.- Smaller molecules are also soluble in water as they can hydrogen bond with the polar water molecules.- Longer chain molecules tend to be insoluble as the hydroxyl group has less effect on the molecule. They can be good solvents for nonpolar molecular compounds (“like dissolves like”).

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O

O

O

O

Try This: 1. Write a balanced equation for the following situations:

a) reacting 2-iodopropane with Ca(OH)2

b) making 1-butene from 1-butanolc) making 1-propanol from propene

2. Why does wine bubble as it is fermenting?

10. 3. Ethers

- These are compound in which oxygen is bonded between two carbon groups.

R1 R2 Notice that this is actually a bent molecule.

Properties: Summary of Hydrogen BondingHydrogen

donorHydrogen acceptor

Boiling point increases

Solubility increases

Halocarbons X XEthers X Alcohols

Nomenclature: The two-alkyl groups are named in alphabetical order and followed by the word “ether”.CH3-CH2-CH2-O-CH3 CH3-CH2-O-CH2-CH3

methylpropyl ether diethyl ether

Try This: 1. The molecular formula C3H8O can represent either two alcohols or an ether. Give

their formulas and names.2. Would an ether be soluble in a) a halocarbon? b) an alcohol?

11. 4. Aldehydes and Ketones

- These two families share certain structural features and chemical properties.- They both contain the carbonyl group C = O, which we will show as (-C(=O)-) in our condensed formulas.- Aldehydes = chain + carbonyl group + hydrogen = R – C – H

- Ketones = chain 1 + carbonyl group + chain 2 = R1 – C – R2

Nomenclature:Aldhydes: change the “_e” ending to “_al”

H – C – H CH3-CH2-CH(=O)methanal propanal

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O

O

Ketones: count the total number of carbons present. Change the “_e” ending to “_one”. Number the carbonyl location.

CH3-C-CH3 CH3-CH2-C(=O)-CH2-CH2-CH3

propanone 3- hexanone

Properties: - They have low boiling points because they have no O – H bonds for hydrogen bonding.- When added to water, though, they can hydrogen bond to the water molecules so they are quite soluble in water.

Try This: Draw and name the aldehyde and the ketone with the molecular formula of C4H8O.

12. 5. Carboxylic Acids

- These organic acids contain the carboxyl functional group, -C(=O)-OH which include both the carbonyl group and the hydroxyl group. In molecular formulas, the carboxyl group is often presented as –COOH.

Properties: Carboxylic acids create the sour taste in foods and have distinctive odors.- They are polar molecules and are both hydrogen acceptors and hydrogen donors. Thus they will readily form hydrogen bonds, and smaller molecules are easily dissolved in water. - They have all of the properties of acids – react with metals, make indicators change color, etc.

Nomenclature: Replace the “_e” ending with “_oic acid”.

structural formula molecular formula condensed formula

CH3-CH2-C-OH C2H5COOH CH3-CH2-C(=O)-OH propanoic acid

Reactions: 1. Fermentation: glucose ethanol ethanoic acid (grape juice) (wine) (vinegar)

2. They undergo typical acid reactions (neutralization, for example) but at a slower rate.

Try This: 1. Name a) CH3-CH2-CH2-C(=O)OH b) CH3-C(CH3)(CH3)-C(=O)OH c) COOH2. Give the formula for a) hexanoic acid b) 3-methylpentanoic acid3. Use the example to write a balanced equation for the organic reaction:

a) KOH + HCl KCl + HOHKOH + CH3-COOH ?

b) 2Na + 2HCl 2NaCl + H2

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Na + CH3COOH ?

13. 6. Esters (Acid + Alcohol Ester)

- Esters are derivatives of carboxylic acids in which the – OH of the carboxyl group has been replaced by an – OR from an alcohol.

OR1-C or R1COOR2 or R1-C(=O)-O-R2

O-R2

Reactions: Esters are prepared by combining a carboxylic acid with an alcohol in a process called esterification:

O O R1-C + HO-R2 R1-C + HOH

OH O-R2

carboxylic acid alcohol ester water Nomenclature: The name of an ester has two parts:

i. Locate the alcohol branch and name it as an alkyl group.ii. Locate the acid branch. The ending of the acid name is changed from “_oic acid”

to “_oate” O alcohol acid

CH3-C CH3-CH2-C(=O)-O-CH2-CH3

O-CH3

methyl ethanoate ethyl propanoate

Properties: -Esters are “odor” chemical (fruits and flowers).- are added to foods to enhance taste + odor.

Try This: Give the esterification reaction (with formulas and names) for i. Propanoic acid and butanol

ii. Butanoic acid + propanoliii. Ethanol and methanoic acid

14. 7. Polymerization

- A polymer is a giant molecule formed by the covalent bonding together of repeating smaller molecules called monomers.

…….. + monomer + monomer + …….. polymer

- One method of creating these polymers by addition polymerization – the joining together of unsaturated (multiple bond) monomers.

If A = the monomer, the polymer will appear as -A-A-A-A- catalyst

n CH2=CH2 (-CH2-CH2-)n

ethane (ethylene) polyethylene

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catalyst

n CH3CH=CH2 (-CH2(CH3)-CH2-)n

propene (propylene) polypropylene

- A condensation polymer is formed by reacting two different compounds together. In order to do this, a small molecule (usually water) must be split off from the functional groups.

If A = first monomer and B = second monomer, then the polymer will appear as -A-B-A-B-Here is a general example:

HO-X-OH + HO-Y-OH (-O-X-O-Y) + 2H2O

“di” acid or “di” alcohol

Note: polyethylene = ice cream plastic containers, polypropylene = nylon rope

Try This: Write the formula for the following polymers, which were formed by addition polymerization.

1. Polyvinyl chloride (PVC) which is made form chloroethane.2. Teflon which is made form tetrafluoroethene.

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