Year 13 Chemistry Notes 2015

Chemistry 3.6 (5 credits)

Describe properties of organic chemistry

Name:

Townshend 2

Learning Outcomes

Use IUPAC conventions to name and draw alkanes with up to eight carbons in their longest chain.

Draw and name the constitutional isomers for an alkane’s given molecular formula.

Explain how the number and arrangement of carbons effects the melting and boiling points of alkanes.

Use IUPAC conventions to name and draw alkenes with up to eight carbons in their longest chain.

Draw and name the constitutional and geometric isomers for an alkene’s given molecular formula.

Explain how the geometric arrangement of the alkene effects the melting and boiling point

Use IUPAC conventions to name and draw haloalkanes with up to eight carbons in their longest chain.

Draw and name the constitutional isomers for an alcohol’s given molecular formula.

Describe how to test for the presence of 1⁰, 2⁰ and 3⁰ alcohols.

Use IUPAC conventions to name and draw amines with up to eight carbons in their longest chain.

Describe how to test for the presence of amines.

Use IUPAC conventions to name and draw aldehydes and ketones with up to eight carbons in their longest chain.

Describe how to test for the presence of aldehydes.

Use IUPAC conventions to name and draw carboxylic acids with up to eight carbons in their longest chain.

Describe how to test for the presence of carboxylic acids.

Use IUPAC conventions to name and draw esters with up to eight carbons in their longest chain.

Describe how to test for the presence of esters.

Townshend 3

Use IUPAC conventions to name and draw acyl chlorides with up to eight carbons in their longest chain.

Describe how to test for the presence of acyl chlorides.

Use IUPAC conventions to name and draw amides with up to eight carbons in their longest chain.

Draw and name triglycerides, glycerol, alanine, glycine.

Identify optical isomers by recognising chiral carbon atoms.

Describe how enantiomers can be distinguished by using polarised light.

Organic Chemistry

Organic chemistry is the study of carbon compounds.

Revision

Organic compounds are made up of chains of carbon atoms bonded together and to hydrogen atoms and other functional group.

Functional group is the group of atoms responsible for the chemical properties of a compound.

Molecular Formula gives the type and number of each atom in a compound eg C2H6.

Structural Formula shows how each atom is arranged and bonded in a compound.

Townshend 4

Alkanes

Use IUPAC conventions to name and draw alkanes with up to eight carbons in their longest chain.

These contain only C-C and C-H bonds. They are called saturated hydrocarbons as the have the maximum number of C-H bonds possible and contain only hydrogen and carbon atoms. Rules for naming organic compounds When naming a specific alkane we need to follow the following steps.

Identify the organic family the molecule is a member of, this will form the last part of the name.

Identify the largest carbon chain. This is the main part of the name.

Count the number of carbon atoms in the longest chain to work out the base of the name. Use the following table to work out the base name of the organic molecule.

Number the carbons on the carbon chain so any branches coming of have the smallest number possible.

The branches are named first with the number of its position on the longest chain preceding it. The name of each branch is dependent on the number of carbons in the branch.

Alkyl branches have the following names Multiple groups are named one after each other. Each identical group must have its own name. Multiple groups have the prefix di (two identical groups), tri (three identical groups) or tetra (four identical groups).

Number of C 1 2 3 4 5 6 7 8 9 10

Prefix meth eth prop but pent hex hept oct non dec

C H

H

H

C C

H

H

H

H

H C C C

H

H

H

H

H

H

Hmethyl ethyl propyl

C C C C CH

H

H

CH2

H H

H H

CH3

H

H

H

CH3

Townshend 5

Exercises

1. Name the following molecules

a) b) c)

2. Draw the following molecules

a) methylpropane b) 2,3-dimethylpentane c) 4-ethyl-2-methyloctane

Condensed Structural Formula

The structural formula represents how the atoms in an organic compound are joined to each other. The structural formulas can be drawn in a condensed form. Each carbon atom in the longest chain is written with atoms attached to written to the right of it.

Brackets can be used to identify alkyl branches(i) or condense long structural formulae(ii).

C C C C CH

H

H

H

H CH3

CH3H

H

H

H

HC C C C CH

H

H

H

H CH3

CH3H

H

H

H

H C C C C CH

H

H

H

CH2

CH3H H

H

C

CH3

H H

H

H

H

C C C CH

H

H

H

H H

H H

H

H CH3CH2CH2CH3

Structural formula Condensed structural

formula

C C C CC

H

CH3

H

H CH3

CH3H

H

C

H

H

H H

H

H

CH3CH(CH3)CH2CH(CH3)2CH2CH3

C C C CC

H

H

H

H H

H H

H

C

H

H

H H

H

H

CH3(CH2)4CH3

i

ii

i

Townshend 6

Exercise

3. Draw the structural formula for each of the following condensed formulae.

Constitutional Isomers

Draw and name the constitutional isomers for an alkane’s given molecular formula.

Alkanes that have the same molecular formula but different structural formulae are called constitutional isomers. Constitutional isomers generally have different physical properties as the shape of each isomer affects intermolecular attraction forces. They can also have different chemical properties.

Drawing Constitutional isomers

Draw the carbon frame.

Starting with the longest chain, draw all possible structure.

Draw all of the possible structures for second longest chain, then third longest chain etc…

Check that each of the structures you have drawn is different to each other.

Draw the complete structures for each of the isomers.

The constitutional isomers of C4H10

Four carbons in the longest chain

Three carbons in the second longest chain

CH3(CH2)8CH3 CH3CH(CH2)CH3

C C CC

C CC

C Each C-C bond can rotate 360° this structure is four carbons in the longest chain. The 1

st carbon is just

twisted up instead of being straight.

Ball and stick model

Townshend 7

So there are just two constitutional isomers for C4H10

Exercise

4. Circle the six different unique constitutional isomers of C6H14.

Six C in the longest chain

Five C in the second longest chain

Four C in the third longest chain

C C C CC C

C C C CC

C

C C C CC

C

CCCC C

C

C C C CC

C

C C C C

C

C

C C C C

C C

C C C C

C

C

C CC

C

C CC

C

These are representations of the same molecule as if you flip one 180⁰ you will get the other.

C C CC

H

H H

H

H

H

HH

H

H

C CC

C

H H

H

HH

H

H

H

H

H

butane methylpropane

C C C C

C

C

Townshend 8

Exercise

5. Draw and name the eight constitutional isomers of C7H16.

Physical Properties of Alkanes

Explain how the number and arrangement of carbons effects the melting and boiling points of alkanes.

The boiling and melting of alkanes generally increase with increasing molecular mass.

Number of C atoms 1 2 3 4 5 6 7 8 9 10

Melting point (°C) -182 -183 -188 -138 -130 -95 -90 -57 -53 -29

Boiling point (°C) -161 -88 -42 0 36 69 99 126 151 174

The most important thing that effect. The difference in electronegativity between carbon and hydrogen is very small so are essentially non-polar.

When a substance dissolves in water the following happen. The hydrogen bonds between the water molecules have to break to accommodate the new molecules and the weak intermolecular bonds between the dissolving molecules need to break. Also weak intermolecular attractions between the molecules and water are formed. The solid will dissolve if the bonds formed are stronger than the bonds broken. In the case of alkanes dissolving in water very strong hydrogen bonds between the water molecules have to be broken but only weak temporary dipole attractions are formed between the alkane molecules and the water particles. The ΔH of this reaction is positive so a lot of energy is needed in order for the alkanes to dissolve. Essentially they are insoluble in water.

Exercises

6. Plot the melting point against the number of carbon atoms and the boiling point against the number of carbon atoms.

Townshend 9

M.p. and B.p vs number of carbons in alkane

On the previous graph, draw a horizontal line at 25° to represent room temperature.

What alkane molecules are liquid at room temperature?

All alkanes are insoluble in water as the intermolecular attractions between alkanes and water are a lot weaker than the intermolecular attractions between water molecules.

Number of carbon atoms

Tem

per

atu

re (

°C)

Townshend 10

Alkenes CnH2n

Use IUPAC conventions to name and draw alkenes with up to eight carbons in their longest chain.

Draw and name the constitutional and geometric isomers for an alkene’s given molecular formula.

Explain how the geometric arrangement of the alkene effects the melting and boiling point

Alkenes are a group of hydrocarbons that contain a double bond. They are unsaturated as the carbons with double bond could potentially have more atoms attached to them.

Naming

Alkenes have the suffix ene instead of ane. The number of the carbon atoms on the main chain the double bond is bonded to is placed before the ene. A cis or trans prefix is used when the alkene is a geometric isomer.

The C=C has more importance than the alkyl functional group so should have the smallest number.

Hint: Be sure each carbon atom only has 4 bonds coming of it.

Stereo isomer - Geometric isomers

Atoms at the end of a single bond can swivel 360, this means it makes no difference at what position a substituent is placed around a carbon atom. However atoms at either end of a double bond cannot rotate and substituents are held firmly in place on one side of the alkene. This gives us two different types of geometric isomers.

C C

H H

4-methylpent-2-ene

C C

CH3

CH3

H

H

C C

H

CH3

H

CH3

C C

CH3

CH

H

H

CH3

CH3

cis trans

Townshend 11

C C CH

H H H

H

H

C C C C

H

H

H H H H

H

H

C C C C

H

H

H H

H CH3

H

H C C C C C

H

H

H Cl

Cl

H

H

H

H

H

An alkene will have geometric isomers if the following two conditions are met:

It has a double bond

It has different substituent groups coming of each carbon of the double bond

The polar cis isomer will have higher melting and boiling points due to the increased strength of the intermolecular attractions caused by the dipole-dipole attractions.

Exercise

7. Draw the following molecules

a) cis but-2-ene b) pent-1-ene c) trans hex-2-ene d) 7-methyloct-2-ene

8. Name the following molecules

a) b) c) d)

C C

H

Cl H

Cl

C C

H

Cl Cl

H

δ- δ- δ-

δ-

δ+ δ+ δ+ δ+

The difference in electronegative between the chlorine and carbon atom produces dipoles. These dipoles, along with the asymmetric shape of the cis isomer cause the molecule to be polar.

The trans isomer also has dipoles, however as this shape is symmetric the dipoles cancel out and the molecule is non-polar.

Townshend 12

Identifying alkenes

The presence of double or triple bonds in a molecule can be identified by using bromine water or permanganate (MnO4

-).

Add 10 drops of alkene ample to 2 mL of bromine water. The orange brome water will become colorless on shaking.

Alkynes CnH(2n-2)

Organic molecules that have a triple bond are called alkenes. These are unsaturated hydrocarbons.

Naming

Alkenes have the suffix yne instead of ane

The number of the carbon atoms on the main chain the double bond comes of is placed before the yne.

.

C C

C C CC

H

H

C

H

H

H H

H

H

C C CH

H

H

H

CH3

C Br

pent-2-yne 1-bromo-3-methylbutane

C C CH

H

H

H H

H + Br2(aq) C C CH

H

H

H

Br

H

Br

H

orange colourless

Townshend 13

Townshend 14

Haloalkanes

Use IUPAC conventions to name and draw haloalkanes with up to eight carbons in their longest chain.

Organic molecules that have a halogen (group 17) functional group are called haloalkanes.

Naming

The main part of the name is the same as for alkanes. The halogen substituents are named, Cl, chloro, Br, bromo and are more , or 3important that alkyl groups when naming.

Classification (1°, 2°, or 3°)

Haloalkanes, alcohols or amines can be classified as primary (1°), secondary (2°) or tertiary (3°) depending on the number of carbon atoms the carbon that is attached to the functional group is bonded to.

C

H

X

C C CH

H

H

H

Br

H

H

HC C CH

H

H

H

CH3

H

H

C

H

Br

H

2-bromopropane 3-methyl-1-bromobutane

C C C C CH

H

H

H

CH2

Cl H H

H

C

CH3

H H

H

H

H

Br C C C

CH2

CH3CH3H

H

C

CH3

H

H

F

H

C C C C CH

H

H

H

H CH3

CH3H

Cl

H

H

H

C C C C CH

H

H

H

H CH3

CH3

H

F

H

H

H

primary tertiary

secondary

secondary

primary

Townshend 15

Exercise

9. Draw the following molecules

a) 1 chloro hexane b) 2,2 dibromo pentane c) cis 2,3 dichloro hex-2-ene

10. Name the following molecules

a) b) c) d)

C C C C CH

H

H

H

H Cl

Cl H

H

H

H

HO C C C

H

CH2

CH3CH3H

Cl

C

CH3

H

Br

H

H

C C C C CH

H

H

H

H CH3

Br

H

OH

H

H

H

C C C C CH

H

Cl

H H H

H

C

Cl H

H

H

H

H

CH3

Townshend 16

Alcohols (Alkanols)

Draw and name the constitutional isomers for an alcohol’s given molecular formula.

Describe how to test for the presence of 1⁰, 2⁰ and 3⁰ alcohols.

An alcohol is an organic compound that contains an OH functional group. The general formula for an alcohol is R-OH where R represents an alkyl group (CH3-, CH3CH2-, CH3CH2CH2-).

Naming

Alcohols are named with the suffix ol replacing the e of an alkane. A number in front of the -ol identifies the carbon the OH substituent is attached to.

Exercise

11. Draw the following molecules.

a) methanol b) propan-2-ol c) butan-1,2-diol d) 3 methyl butan-2-ol

12. Name the following molecules

a) b) c) d)

C

H

OH

pentan-2-ol 5-methylhexan-2-ol

C C C C CH

H

H

H

OH H

H H

H

H

H

H C C C C C CH

H

H

H

CH3H

H H

H OH

H H

H

H

Hydroxyl groups are given the lowest number possible

C C C C CH

H

H

H

H CH3

CH3H

OH

H

H

H C C C C CH

H

H

H

H CH3

CH3OH

H

OH

H

H C C C C CH

H

H

H

CH2

OH H H

H

C

CH3

H H

H

H

H

O C C C

H

CH2

CH3CH3H

H

C

CH3

H

H

H

H

Townshend 17

Identifying alcohols – Oxidising agents

Primary or secondary alcohols react with the common oxidants acidified dichromate (Cr2O72-

/H+) and

acidified permanganate (MnO4-/H

+)

Add 10 drops of acidified permanganate to alcohol sample. Purple solution will quickly become colourless is 1° or 2° alcohol is present.

Add 10 drops of acidified dichromate to alcohol sample and heat. The orange solution will turn green/blue if 1° or 2° alcohol is present

Identifying alcohols – Lucas Reagent

The ability and rate of primary, secondary and tertiary alcohols reacting with Lucas reagent can be used as a way to distinguish between these three types of alcohol. Lucas reagent is a mixture of concentrated hydrochloric acid and ZnCl2 (This acts as a catalyst)

Add 5 drops of alcohol sample to 2 mL of Lucas Reagent in a test tube. Shake and observe. If the solution goes cloudy a tertiary alcohol is present. If the solution does not do cloudy, place the test tube in a water bath 30° for 5 min. If the solution goes cloudy after the second step a secondary alcohol is present.

C C C CH

H

H

H

H OH

H H

H

H

Cr2O7

2-/H

+

C C C CH

H

H

H

H O

H

H

H

C C C

H

H H

H H

OH

HH

MnO4

-/H

+

C C C OHH

H

H

H

H O

C C C CH

H

H

H

H OH

CH3H

H

H

HCl/ZnCl2

C C C CH

H

H

H

H Cl

CH3H

H

H

C C C

H

H OH

H H

H

HH

HCl/ZnCl2

C C C

H

H Cl

H H

H

HH

Heat 5 min.

Townshend 18

Hydrogen bond Hydrogen atom bonded to same

carbon as N, O or F atom.

Lone pair of electrons on N, O or F

atom.

Townshend 19

Townshend 20

Amine

Use IUPAC conventions to name and draw amines with up to eight carbons in their longest chain.

Describe how to test for the presence of amines.

Amines are a group of organic molecules that contain the –NH2 functional group. Amines can be classified as primary, secondary or tertiary amines.

Amides can be classified as 1, 2 or 3 depending on how many carbons are bonded to the N atom.

Naming

Primary amines are named by putting the prefix amino and the name of the alkane chain. A number may be needed to say which carbon the NH2 is attached to.

Identification of amines

The smell of decomposing fish is caused by a 3° amine. All amines are weak bases, they form alkaline solutions when they are mixed with water and can be neutralized by reacting them with acids.

Add 10 drops of amine sample to 2 mL of water in a test tube and shake. Test the solution with some red litmus paper, if it goes blue then the sample is basic and probably an amine.

C

H

NH2

2-aminopropane 3-aminoheptane

C C CH

H

H

H

NH2

H

H

H C C C C C C CH

H

H

H

H NH2

H H

H H

H H

H

H

H

H

C C C

H

H NH2

H H

H

HH C C C

H

H NH3

+

H H

H

HH+ OH2 OH3

++

C C C

H

H H

NH2

H

H

H

H

C C N CH3

HH

H

H H

H1⁰ 2⁰ 3⁰

C C N CH3

CH3H

H

H H

H

Townshend 21

Exercise

13. Name the following molecules

a) b) c) d)

e) NH2CH2CH3 f) CH3(CH2)6CH(NH2)CH3 g) CH3CH2CH(NH2)CH2CH3

14. Draw the following molecules

a) 1-aminoheptane b) aminomethane c) 3-aminooctane

15. Classify the following as 1, 2 or 3 amines.

a) b) c)

C C C C HH

H

H

H

H NH2

H H

H

NH2 C C C

CH3

H

H

NH2

H

H

H

C C C C CH

H

NH2

H H H

NH2

C

Cl H

H

H

H

H

CH3

NH2 C C C

CH2

H H H

H

C

CH3

H

Br

H

H

NH2 C C C

CH2

H H H

H

C

CH3

H

Br

H

H C C C C CH

H

H

H H H

H

C

Cl H

H

H

H

NH2

CH3

NH2 C C C

CH3

H

H

NH2

H

H

H

Townshend 22

Aldehydes and Ketones

Use IUPAC conventions to name and draw aldehydes and ketones with up to eight carbons in their longest chain.

Describe how to test for the presence of aldehydes.

Aldehydes

Aldehydes are a group of organic compounds that contain a double bond oxygen at the end of a molecule

Naming

Aldehydes are named on the same way as alkanes but the e on the end of an alkane is replaced by al.

Ketones

Ketones are a group of organic compound that contain a carbon oxygen double bond not at the end of a molecule.

Naming

Ketones are named by replacing the e of alkane with one and by placing the number of the carbon the double bond oxygen is attached to just before.

.

C

O

H

butanal 3-ethyloctanal

C C C CH

H

H

H

H H

H

O

HC C C C C C C C

CH2

CH3

O

H

H

H

H H

H

H

H

H

H

H

H

H

H

H

C

O

propanone 2-bromhexan-3-one

C C CH

H

H O

H

H

H C C C C C CH

H

H

H

Br O

H

H H

H H

H

H

Townshend 23

Exercise

16. Draw the following molecules

a) pentanal b) butan-2-one c) methanal d) 5-methyl-heptan-2-one

17. Name the following molecules

a) CH3CH2CH2CHO b) CH3COCH2 c) CH3CH2COCH2CH3

d) e) f)

Identification of aldehydes and ketones

The carbonyl group in ketones is attached directly to carbon atoms so they cannot be easily oxidised. As aldehydes have a hydrogen atom attached directly to the carbonyl group the can be easily oxidised by weak oxidising agents containing Cu

2+

and Ag+. These oxidising agents will not oxidise alcohols so they are a specific test

for the presence of an aldehyde group.

Tollen’s reagent is a common test for aldehydes. It is distinctive as it produces a silver mirror when aldehydes are present.

Fehling’s solution is another test for aldehydes. Fehling’s solution contains Cu2+

ions and so has a distinctive blue colour. When the solution has a positive reaction with an aldehyde group orange Cu2O(s) is produced.

C C C

H

H H

H

O

HH C C C

H

H H

H

O

O-

H+ 2H2O+2[Ag(NH3)2]2+

+ OH-

4NH32Ag(s) + +

Tollen's reagent silver mirror

C C C C HH

H

H

H

H O

H

H

C C C C

CH3

H

H O

H

H

H

HH

C C C C CH

H

H

H H H

H

C

Cl H

H

H

HO

Townshend 24

Carboxylic acids

Use IUPAC conventions to name and draw carboxylic acids with up to eight carbons in their longest chain.

Describe how to test for the presence of carboxylic acids.

Carboxylic acids are a group of organic compounds that contain the COOH functional group.

Naming

Carboxylic acids are named by putting a suffix –oic acid on the end of the name.

Exercise

30 Draw the following molecules

a) propanoic acid b) hexanoic acid c) methanoic acid d) 5-ethyloctanoic acid

31 Name the following molecules

a) CH3CH2CH2COOH b) CH3(CH2)5CO2H c)

C

O

OH

propanoic acid 5-bromohexanoic acid

C C CH

H

H O

OH

H

H

CH3 CH CH2CH2CH2C

Br O

OH

The numbering always starts from the COOH functional group.

C C C C CH

H

H

H

H H

H H

H O

OH

Townshend 25

Identification of carboxylic acids

All carboxylic acids are weak acids, they form acidic solutions when they are mixed with water and can be neutralized by reacting them with bases.

Add 10 drops of carboxylic acid sample to 2 mL of water in a test tube and shake. Test the solution with some blue litmus paper. If the paper goes red then the sample is acidic and possibly a carboxylic acids.

C C C

H

H H

H

O

OHH C C C

H

H H

H

O

O-

H+ OH2 OH3

++

Townshend 26

Esters

Use IUPAC conventions to name and draw esters with up to eight carbons in their longest chain.

Describe how to test for the presence of esters.

Esters are a group of organic compounds that contain the –COO- functional group.

Naming

Esters have two parts to their name. If we split the molecule at the -O- bond then there is an alkyl side and the side with the carbon oxygen double bond.

Exercise

39 Draw the following molecules.

a) methylpropanoate b) propylbutanoate c) pentylethanoate

40 Name the following molecules

a) b) c) CHOOCH2CH2CH3

d) e)

ethylpropanoate propylmethanoate

C

O

O

C C C

O C C

OH

H H

H

H

H H

HH

H C

O C C C

O

H

H H

H H

H

H

H

C C C O C C

H

H

H H

H O H

H H

H

H

CCCOCC

H

H

HH

HOH

HH

C

H

H

H

H

COCC

OH

HH

C

H

H

H

H

H

C C C O C C

H

H

H H

H O H

H H

C

H

H

C

H

H

C

H

H

C

H

H

H

H

Townshend 27

Identification of esters

Esters are insoluble in water and will often appear as an oily layer floating on top of water. They have a sweet fruity smell.

Townshend 28

Acyl chlorides CnH2n

Use IUPAC conventions to name and draw acyl chlorides with up to eight carbons in their longest chain.

Describe how to test for the presence of acyl chlorides.

Acyl chlorides are a group of organic compounds that contain the COCl functional group.

Naming

Acly chlorides are named by replacing the e of alkane with oyl chloride and by placing the number of the carbon the double bond oxygen is attached to just before.

Exercise

18. Draw the following molecules

a) butanoyl chloride b) ethanoyl chloride c) heptanoyl chloride

19. Name the following molecules

a) CH3COCl b) c) CH3(CH2)4COCl

d) e) f)

C

O

Cl

ethyl chloride butanoyl chloride

C C ClH

H

H O

Cl C C C C

O

H

H H

H H

H

H

C C C ClH

H

H

H

H O

ClCCH2CH2CH2

O

CH3 Cl C C C C

O

H

H CH3

H H

H

H ClCCCC

O

H

HH

HH

H

C

H

C

Br

H

H

H

Townshend 29

Identification of acids chlorides

Acyl chlorides react violently when added to water.

Add five drop of acyl chloride sample to water. Test the gas evolved with moist blue litmus paper. If the sample reacts vigorously and the gas evolved is acid then the sample is an acyl chloride.

C C C

H

H H

H

O

ClH C C C

H

H H

H

O

OHH+ OH2 + HCl(g)

Townshend 30

Amides

Use IUPAC conventions to name and draw amides with up to eight carbons in their longest chain.

Amides are a group of organic compounds that contain the CONH2 functional group.

Amides can be classified as 1, 2 or 3 depending on how many carbons are bonded to the N atom.

Naming

Primary amides are named by replacing the e of alkane with amide. Secondary amides are named by using thre prefix N istead of a number to when aming the alkyle group.

.

Exercise

20. Draw the following molecules

a) methanamide b) heptanamide c) propanamide

21. Name the following molecules

a) CH3CONH2 b) CH3CH2CH2CONH2 c)

C

O

NH2

butanamide N-methylethanamide

C C NH

H

H O

CH3

H

NH2CCCC

O

H

HH

HH

H

H

C C C C CH

H

H

H

H H

H H

H O

O

NH2

C C C

H

H H

H O

O NH2H C C C

H

H H

H O

O NH CH3

H

C C C

H

H H

H O

O NH CH3

CH3

1⁰ 2⁰ 3⁰

Townshend 31

Townshend 32

Amino acids

Draw and name triglycerides, glycerol, alanine, glycine.

Identify optical isomers by recognising chiral carbon atoms.

Describe how enantiomers can be distinguished by using polarised light.

Amino acids are a group of organic compounds that contain the both the COOH and the NH2 functional groups. There are 20 different amino acids that the human body uses to synthesize proteins. 12 of these our bodies can make themselves, 8 have to be sourced from our diet already made, they are called essential amino acids

Naming

Each Amino acid has its own specific name. We need to learn the name and structure of the two simplest α amino acids glycine and alanine.

.

Optical Isomers

Alanine has a carbon atom that has four different substituents attached to it, this is called a chiral carbon. Because of this Alanine can be one of two mirror images (enantoimers).

C C NH2

O

OH

R2

R1

C C NH2

O

OH

H

H

C C NH2

O

OH

CH3

H

glycine alanine

CCNH2

OH

OH

H

L R

Townshend 33

An optical isomer cannot be superimposed (placed on top) of its image.

Right and left hands are optical isomers as they are mirror images but cannot be superimposed on top of each other.

Biological systems are so picky that only one of these optical isomers is used by our body. Optical isomers have identical physical and chemical properties but different biological properties.

A pure mixture of an enantiomer will rotate polarised light in an opposite direction to its optical isomer.

Exercise

22. Draw the following molecules

a) Alanine b) Glycine

L

L

R

R

Chiral carbon

Townshend 34

23. Which of the following molecules can exist as optical isomers, draw the molecules and put an * beside any asymmetric carbon?

a) 2-methylbutan-2-ol b) 1-chloropropane c) pentan-2-ol

24. Draw a 3-D representation for the two enantiomers of 2-chlorobutane.

Solubility of Organic compounds

There are two major factors that affect the solubility of organic compounds.

The molar mass of the molecule: The larger the molar mass of an organic molecule the less likely it will be soluble in water.

Presence of NH2 or OH functional groups: The amine and hydroxyl functional groups are able to form an especially strong type of intra-molecular attraction with water. This attraction is called a hydrogen bond.

Melting and boiling point of Organic compounds

There are three major factors that affect the solubility of organic compounds.

The molar mass of the molecule. The more carbon atoms an organic molecule has the larger the molar mass and the larger the inter-molecular attraction

Highly electronegative elements O, N and the halogens can create polar molecules increasing inter-molecular attractions

The presence of NH2 or OH functional groups: The amine and hydroxyl functional groups are able to form especially strong hydrogen bond between molecules.

Townshend 35

Exercise

25. Name the following molecules

1. 2.

3. 4.

5. 6.

7. 8.

9. 10.

11. 12.

13. 14.

15. 16.

17. 18.

CH3 CH2 CH2 CH2 CH3

CH3 CH2 CH2 CH3

CH3 CH2 CH3

CH3 CH3CH3 CH2 CH2 CH CH2 CH3

OH

CH3 CH2 CH2 CH CH3

OHCH3 CH2 CH2 CH2 OH

CH3 CH CH3

OHCH3 CH2 OH

CH3 CH2 CH CH CH2 CH3 CH3 CH CH CH2 CH3

CH3 CH CH CH3 CH2 CH CH3

CH2 CH2 CH3 C C CH2 CH2 CH3

CH C CH2 CH2 CH3 CH3 C C CH3

CH3 CH CH2 CH3

CH3

Townshend 36

19. 20.

21. 22.

23. 24.

25. 26.

27. 28.

29. 30.

31. 32.

33. 34.

35. 36.

37. 38.

CH3 CH2 Cl

CH3 CH CH3

Br

CH C CH3 CH CH

CH3 CH2 CH2 C CH2 CH3

CH3

CH3

CH3 CH CH CH2 CH3

CH3

CH3

CH3 C CH3

CH3

ClCH3 CH3

CH3 CH2 CH2 CH CH2 CH3

Cl

CH3 CH2 CH2 CH CH3

Cl

CH3 CH2 CH2 CH2 Br

CH3 CH2 C OH

O

CH3 CH2 CH2 CH2 CH2 C OH

O

CH3 CH2 CH2 C OH

O

CH3 CH2 CH CH2 Br

OH

CH2 CH CH2 CH2 OH

CH3 CH2 CH CH2 Cl

CH3CH3

C C

CH3H

H

H

C C

CH3H

HH

C C

CH3CH3

H

Townshend 37

39. 40.

41. 42.

43. 44.

45. 46.

47. 48.

49. 50.

51. 52.

53. 54.

55. 56.

57. 58.

CH3

C C

CH2H

H

CH3CH3 CH2 C O CH2 CH3

O

CH3 CH2 C O CH3

O

CH3 C O CH2 CH3

O

CH3 CH2 C O CH2 CH3

O

CH3 O C CH2 CH2 CH2

O

CH3

CH3 CH2 CH2 CH OH

OH

CH3 C CH2 CH OH

Cl

H

Cl

CH3 C CH3

CH3

NH2

CH2 CH2

NH2

NH2

CH3 CH2 CH2 C CH2 CH3

O

CH3 CH2 CH2 C CH3

O

CH3 C CH3

O

CH3 CH2 CH2 C H

O

CH3 C H

O

CH3 CH2 CH2 CH2 CH2 C NH2

O

CH3 CH2 CH2 C NH2

O

CH3 CH2 CH C NH2

OH O

CH3 CH2 C Cl

O

CH3 CH2 CH2 C Cl

O

Townshend 38

59. 60.

61. 62.

63. 64.

CH3 CH2 CH C Cl

CH3 O

CH3 CH2 C O CH2 CH3

O

CH3 CH2 C N CH3

O H

CH3 C NH CH2 CH3

O

NH2 CH2 C OH

O

NH2 CH C OH

O

CH3

Townshend 39

Exercise

26. Describe the expected observations for each of the distinguishing tests below.

Functional Group Distinguishing tests Observations

Alkene Add 5 drops to bromine water

Add 5 drops to permanganate solution

1⁰ alcohol Add 5 drops to acidified dichromate

Add 5 drops to acidified permanganate

2⁰ alcohol Add 1 ml to Lucas reagent

Add 5 drops to acidified dichromate

3⁰ alcohol Add 1 ml to Lucas reagent

aldehyde Add 5 drops to Fehling’s solution and heat.

Carry out silver mirror test (Tollen’s reagent)

amine Test with red litmus paper

enantiomer Shine polarised light through a solution of one of the enantiomers

carboxylic acid Test with blue litmus paper

Mix with sodium bicarbonate solution

acid chloride Add 5 drops to water. Test solution with moist blue litmus paper

C

H

H

NH2

Cl C

H

CH3

NH2*

C X

C

H

H

OH

C

OH

H

C

OH

H

C

O

OH

C

O

Cl

C

O

H

Townshend 40

Exercise

27. Describe a sequence of tests you could carry out to distinguished between

unlabeled samples of propan-1-ol, propan-2-ol, propanal and propanone.

Townshend 41

28. Describe how you could distinguished between unlabeled bottles of the liquids of

1-aminobutane, butanoic acid, butanoyl chloride, butan-1-ol and butanone using

just water and blue and red litmus paper.

Townshend 42

Exercise

29. Highlight and name the functional groups present in each og the following

organic molecules that we meet in our everyday lives.

dopamine

Dopamine is commonly associated with the pleasure system of the brain, providing feelings of enjoyment and reinforcement to motivate a person proactively to perform certain activities.

tetrahydrocannabinol (chocolate)

salicylic acid (aspirin)

paracetamol

vitamin C

Salbutamol (asthma)

Townshend 43

In the central nervous system, serotonin is believed to play an important role in the regulation of anger, aggression, body temperature, mood, sleep, vomiting, and appetite.

serotonin

oestrogen

testosterone

cholesterol

Townshend

Key Word Definitions

acyl chloride

alanine

alcohol

aldehyde

alkane

alkene

alkyl group

alkyne

amide

amine

amino acid

boiling point

bromine water

carbonyl group

carboxylic acid

chiral carbon

cis

classification

condensed structural formula

Townshend

constitutional isomer

double bond

enantiomer

ester

functional group

geometric isomer

glycine

haloalkane

hydrocarbon

hydroxyl group

Intermolecular attraction forces

isomer

ketone

litmus paper

Lucas reagent

melting point

molecular formula

optical isomer

polarised light

room temperature

saturated

Townshend

soluble

structural formula

substituents

Tollen’s reagent

trans

unsaturated