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Unit 2 The World of Carbon Menu Fuels Nomenclature Reactions of Carbon Compounds Polymers Natural Products.

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Presentation on theme: "Unit 2 The World of Carbon Menu Fuels Nomenclature Reactions of Carbon Compounds Polymers Natural Products."— Presentation transcript:

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2 Unit 2 The World of Carbon

3 Menu Fuels Nomenclature Reactions of Carbon Compounds Polymers Natural Products

4 Fuels

5 Crude oil Crude oil is a source of many fuels. It is also the principal feedstock for the manufacture of petroleum-based consumer products because these are compounds of carbon.

6 Petrol Petrol can be produced by the reforming of naphtha. Reforming alters the arrangement of atoms in molecules without necessarily changing the number of carbon atoms per molecule.

7 Aromatic hydrocarbon Branched-chain hydrocarbon Cycloalkane As a result of the reforming process, petrol contains branched-chain alkanes, cycloalkanes and aromatic hydrocarbons as well as straight-chain alkanes.

8 Any petrol is a blend of hydrocarbons which boil at different temperatures. A winter blend of petrol is different from a summer blend. In winter butane is added to petrol so that it will catch fire more easily.

9 Engines In a petrol engine, the petrol-air mixture is ignited by a spark. ‘Knocking’ is caused by auto-ignition. Auto-ignition is when the petrol-air mix ignites too soon due to the heat from the engine. This makes the engine perform badly. Knocking is when the engine shakes and shudders.

10 The tendency of alkanes to auto- ignite used to be reduced by the addition of lead compounds. Unfortunately the lead compounds cause serious environmental problems.

11 Unleaded petrol uses components which have a high degree of molecular branching and/or aromatics and/or cycloalkanes to improve the efficiency of burning.

12 Alternative fuels Fossil fuels are going to run out in the future. Fuels used produce carbon dioxide, which increases the “greenhouse effect”. We need other fuels which are renewable and non-polluting.

13 Sugar cane is a renewable source of ethanol for mixing with petrol. Some biological materials,(i.e. manure and straw) under anaerobic conditions, ferment to produce methane (biogas). Methanol is an alternative fuel to petrol, but it has certain disadvantages, as well as advantages.

14 Methanol Almost complete combustion No carcinogens Cheaper than petrol Less explosive than petrol Little modification to car engine Difficult to mix with petrol Very corrosive Toxic Larger fuel tanks needed.

15 Hydrogen could well be the fuel of the future. If water can be electrolysed, using a renewable energy source, such as solar power, hydrogen will be obtained. The hydrogen will burn, producing water, and so will be pollution-free. The problem with hydrogen is storing the gas in large enough quantities.

16 Fuels Click to repeat Fuels Click to return to the Menu Click to End

17 Nomenclature & Structural formula

18 Nomenclature Nomenclature means the way chemical compounds are given names. These names are produced by a special system.

19 Naming organic compounds All organic compounds belong to “families” called homologous series. A homologous series is a set of compounds with the same general formula, similar chemical properties and graded physical properties.

20 Most homologous series have a special functional group. A functional group is a reactive group of atoms which are attached to the carbon chain. The functional group is the part of the molecule where most reactions take place.

21 Functional Groups Functional Group Name of Group Homologous series noneAlkanes Double bondAlkenes Triple bondAlkynes HydroxylAlkanols (Alcohols) C C O H

22 Functional Groups Functional Group Name of Group Homologous series CarbonylAlkanals (Aldehydes) CarbonylAlkanones (Ketones) CarboxylicAlkanoic acids AmineAmines C H O C O C OH O NH 2

23 The first part of the compound’s name is decided by the number of carbon atoms in the molecule. The second part of the name is decided by the homologous series to which the compound belongs.

24 Number of C atoms First part of name Number of C atoms First part of name 1meth-5pent- 2eth-6hex- 3prop-7hept- 4but-8oct-

25 2 nd Part of Name Homologous series General Formula Name ending AlkanesC n H 2n+2 …ane AlkenesC n H 2n …ene AlkynesC n H 2n-2 …yne AlkanolsC n H 2n+1 OH…anol

26 2 nd Part of Name Homologous series General Formula Name ending AlkanalsC n H 2n+2 …anal AlkanonesC n H 2n …anone Alkanoic acids C n H 2n-2 …anoic acid AminesC n H 2n+1 OH…ylamine

27 This method works well for straight-chain hydrocarbons. Here is an example: hexane H H H H H H H C C C C C C H H H H H H H

28 We have to add rules to help deal with branched chains. H H H H CH 3 H H C C C C C C H H H CH 3 H CH 3 H

29 First draw out the full structure. H H H H CH 3 H H C C C C C C H H H CH 3 H CH 3 H

30 Number the atoms in the longest continuous carbon chain. Start at the end nearer most groups. H H H H CH 3 H H C C C C C C H H H CH 3 H CH 3 H

31 This now gives us the basic name – in this case hexane. H H H H CH 3 H H C C C C C C H H H CH 3 H CH 3 H

32 You must now identify any side chains. -CH 3 is methyl -CH 2 CH 3 is ethyl

33 Now identify and count the number and type of side chain. di - shows 2 tri – shows 3 tetra – shows 4 Label the carbon atom(s) they join

34 This now gives us the full name: 2,2,4 trimethylhexane. H H H H CH 3 H H C C C C C C H H H CH 3 H CH 3 H

35 Naming other homologous series works in the same way. With those we start numbering at the end nearer the functional group e.g. this alkene: H H H H CH 3 H H C C C C C C H H C 2 H 5 CH 3 H

36 Number the atoms in the longest carbon chain. H H H H CH 3 H H C C C C C C H H C 2 H 5 CH 3 H

37 This now gives us the basic name – in this case hex-2-ene. H H H H CH 3 H H C C C C C C H H C 2 H 5 CH 3 H

38 Identifying the side chains gives us the full name: 5,5 dimethy 4 ethyl hex-2-ene. H H H H CH 3 H H C C C C C C H H C 2 H 5 CH 3 H

39 We can use the same principles with cyclic hydrocarbons. H H C H C C H C C H H H CH 3

40 1 methyl cyclopentane H H C H C C H C C H H H CH

41 Isomers Isomers are compounds with the same molecular formula but different structural formulae For example C 4 H 10 H C C C C H H H butane H C C C H H H H H C H H H 2 methyl propane

42 Alcohols The alcohols form another homologous series – called the alkanols. We can recognise the alkanols because they contain an OH group. They are given names as if they are substituted alkanes.

43 3 methyl pentan-2-ol H H CH 3 H H H C C C C C H H H H OH H 12345

44 Aldehydes The aldehydes form another homologous series – called the alkanals. We can recognise the alkanals because they contain a carbonyl group at the end of the carbon chain. They are named as if they are substituted alkanes.

45 3,4 dimethyl pentanal We don’t need to number the carbonyl group because it must be on the first carbon. H H CH 3 H H H C C C C C O H CH 3 H H 12345

46 Ketones The ketones form another homologous series – called the alkanones. We can recognise the alkanones because they contain a carbonyl group in the middle of the carbon chain. They are named as if they are substituted alkanes.

47 3,3 dimethyl pentan-2-one H H CH 3 H H C C C C C H H H CH 3 O H 12345

48 Alkanoic acids The alkanoic acids form another homologous series. Carboxylic acids are used in a variety of ways.

49 Alkanoic acids We can recognise the alkanoic acids because they contain a COOH group. C OH O

50 We can name the alkanoic acids using the principles we have used before. H H CH 3 H H H C C C C C H H H H H C OH O

51 4 methyl hexanoic acid We don’t need to number the acid group because it must be on the first carbon. H H CH 3 H H H C C C C C H H H H H C OH O 6

52 Esters An ester can be identified the ‘-oate’ ending to its name. The ester group is: C O O

53 Esters An ester can be named given the names of the parent alkanol and alkanoic acid. The name also tells us the alkanoic acid and alkanol that are made when the ester is broken down.

54 CH 3 CH 2 C OH O The acid and alkanol combine

55 HO CH 3 The acid and alkanol combine

56 CH 3 CH 2 C OH O HO CH 3 The acid and alkanol combine Water is formed.

57 CH 3 CH 2 C O O CH 3 H2OH2O

58 Naming esters Acid nameAlkanol nameEster name ethanoic acidmethanolmethyl ethanoate propanoic acidethanolethyl propanoate butanoic acidpropanolpropyl butanoate methanoic acidbutanolbutyl methanoate

59 A typical ester is shown below. H H O H H H C C C O C H H H H C H

60 We can identify the part that came from the alkanoic acid – propanoic acid. H H O H H H C C C O C H H H H C H

61 We can identify the part that came from the alkanol - ethanol H H O H H H C C C O C H H H H C H

62 This gives us the name ethyl propanoate H H O H H H C C C O C H H H H C H

63 Aromatic Hydrocarbons Benzene is the simplest aromatic hydrocarbon. It has the formula C 6 H 6. The benzene molecule has a ring structure.

64 Even though benzene would seem to be unsaturated it does not decolourise bromine water. All the bonds in benzene are equivalent to each other – it does not have the usual kind of single and double bonds.

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66 The bonds in benzene are intermediate between single and double bonds. Their lengths and bond energies are in between those of single and double bonds.

67 The stability of the benzene ring is due to the delocalisation of electrons. A benzene ring in which one hydrogen atom has been substituted by another group is known as the phenyl group. The phenyl group has the formula - C 6 H 5.

68 Benzene and its related compounds are important as feedstocks. One or more hydrogen atoms of a benzene molecule can be substituted to form a range of consumer products.

69 Nomenclature and Structural Formula Click to repeat Nomenclature and Structural Formula Click to repeat Nomenclature and Structural Formula Click to return to the Menu Click to End

70 Reactions of Carbon Compounds

71 Saturated Hydrocarbons Alkanes and cycloalkanes are saturated hydrocarbons. Saturated hydrocarbons contain only carbon to carbon single covalent bonds.

72 Unsaturated Hydrocarbons The alkenes are unsaturated hydrocarbons. Unsaturated hydrocarbons contain at least one carbon to carbon double covalent bond.

73 Addition Reactions Addition reactions take place when atoms, or groups of atoms, add across a carbon to carbon double bond or carbon to carbon triple bond.

74 For alkenes the basic reaction is: H H H H C C + * *  C C * *

75 When bromine adds to an alkene we have an addition reaction. C 4 H 8 + Br 2  C 4 H 8 Br 2 H H H H C C + Br Br  C C Br Br

76 The addition reaction between hydrogen chlkoride and an alkene gives the equivalent alkyl chloride. C 3 H 6 + HCl  C 3 H 7 Cl H H H H C C + H Cl  C C H Cl propene + hydrogen chloride  propyl chloride

77 Halogenoalkanes Halogenoalkanes have properties which make them useful in a variety of consumer products. In the atmosphere, ozone, O 3, forms a protective layer which absorbs ultraviolet radiation from the sun. The depletion of the ozone layer is believed to have been caused by the extensive use of certain CFCs (chlorofluorocarbons).

78 The addition reaction between water and an alkene gives the equivalent alkanol. propene + water  propanol C 3 H 6 + H 2 O  C 3 H 7 OH H H H H C C + H 2 O  C C H OH

79 Sometimes addition reactions can give two different isomeric products. CH 2 =CH-CH 3 CH 2 Cl-CH 2 -CH 3 CH 3 -CHCl-CH 3 HCl

80 Ethanol To meet market demand ethanol is made by means other than fermentation. Industrial ethanol is manufactured by the catalytic hydration of ethene. H H H H H C C H + H 2 O  H C C H H OH

81 Ethanol can be converted to ethene by dehydration. This reaction uses aluminium oxide or concentrated sulphuric acid as a catalyst. H H H H H C C OH  C C + H 2 O H H H H

82 For alkynes the reaction takes place in two stages: C C + * *  C C * * * * * * C C + * *  C C * *

83 With hydrogen: CH CH 2 CH 3 H2H2 H2H2

84 With a halogen: CH CHX CHX 2 X2X2 X2X2

85 With a halogen halide: CH CHX CH 2 CHX 2 CH 3 HX CH 2 X HX

86 The benzene ring resists any addition reactions. Its delocalised electrons mean that its bonds do not behave like the bonds in an unsaturated compound

87 Alcohols There are three types of alcohols: Primary Secondary Tertiary

88 Primary Alcohols Primary alcohols have at least two hydrogen atoms on the carbon atom carrying the OH group. H C OH H

89 Secondary Alcohols Secondary alcohols have one hydrogen atom on the carbon atom carrying the OH group. H C OH

90 Tertiary Alcohols Tertiary alcohols have at no hydrogen atoms on the carbon atom carrying the OH group. C OH

91 Oxidation and Reduction Oxidation and reduction can be described in terms of loss or gain of electrons. In organic chemistry it is more useful to describe them differently.

92 Oxidation is an increase in the oxygen to hydrogen ratio e.g. CH 3 CH 2 OH  CH 3 CHO 1:6 1:4 Reduction is a decrease in the oxygen to hydrogen ratio. CH 3 CO 2 H  CH 3 CH 2 OH 2:4 1:6

93 Oxidation Reactions The simplest oxidation reaction of alcohols is when they are burned in oxygen, giving carbon dioxide and water. Some alcohols can be oxidised to give aldehydes and ketones.

94 Primary alcohols can be oxidised in two stages : first to an aldehyde H R C O H H R C O Primary alcohol  Aldehyde

95 Primary alcohols can be oxidised in two stages : first to an aldehyde and then to an alkanoic acid. H R C O H H R C O H R C O OH R C O Primary alcohol  Aldehyde Aldehyde  Alkanoic Acid

96 Secondary alcohols can be oxidised only once: to a ketone R* R C O H H R* R C O Secondary alcohol  Ketone No further oxidation is possible

97 Tertiary alcohols cannot be oxidised at all. R* R C O H R** No oxidation is possible

98 Aldehydes can be oxidised to give carboxylic (alkanoic) acids while ketones cannot. This can be used as a means of differentiating between aldehydes and ketones. The oxidising agents that are used most often give visible signs of reaction.

99 ReagentVisible effect Acidified permanganatePurple  colourless Acidified dichromateOrange  green Copper oxideBlack  brown Tollen’s ReagentSilver mirror produced Fehling’s solutionBlue  red Benedict’s solutionBlue  red

100 Condensation Reactions In a condensation reaction, the molecules join together by the reaction of the functional groups to make water. H HO H2OH2O

101 Esters Esters are formed by the condensation reaction between a carboxylic acid and an alcohol. Uses of esters include flavourings, perfumes and solvents.

102 Esters Esters can be recognised by the ester link shown below: C O O

103 The ester link is formed by the reaction of a hydroxyl group of an alkanol with a carboxyl group of a carboxylic acid. H H HO C C H H H

104 The ester link is formed by the reaction of a hydroxyl group of an alkanol with a carboxyl group of a carboxylic acid. H H HO C C H H H

105 The ester link is formed by the reaction of a hydroxyl group of an alkanol with a carboxyl group of a carboxylic acid. H H O H C C C O H H H

106 The ester link is formed by the reaction of a hydroxyl group of an alkanol with a carboxyl group of a carboxylic acid. H H O H C C C O H H H

107 H H O H C C C O H H H Carboxylic acid H H HO C C H H H Alkanol

108 H H O H C C C O H H H HO C C H H H

109 H H O H C C C O H H H HO C C H H H Water is formed from hydrogen of one molecule and hydroxide from the other.

110 H H O H C C C O H H C C H H H H2OH2O Water is formed from hydrogen of one molecule and hydroxide from the other.

111 H H O H C C C O H H C C H H H H2OH2O Water is formed from hydrogen of one molecule and hydroxide from the other. The remains of the molecules join together

112 H H O H C C C O H H C C H H H H2OH2O Water is formed from hydrogen of one molecule and hydroxide from the other. The remains of the molecules join together

113 Hydrolysis Reactions In a hydrolysis reaction, a molecule is split up by adding the elements of water. H HO H2OH2O

114 The carboxylic acid and the alcohol from which the ester are made can be obtained by hydrolysis. CH 3 CH 2 COOCH 3 CH 3 CH 2 COOH + H 2 O + CH 3 OH

115 The formation and hydrolysis of an ester is a reversible reaction. Acid + alkanol Ester + water hydrolysis condensation

116 Yields If we write the equation for a reaction we can calculate what mass of product should be produced – the theoretical yield. When we carry out the experiment we can measure the mass of product produced – the actual yield.

117 Percentage Yield Percentage yield is the actual yield, expressed as a percentage of the theoretical yield. Percentage Yield Actual Yield Theoretical Yield = X 100 1

118 Percentage Yield Actual Yield Theoretical Yield = X 100 1

119 Titanium dioxide, TiO 2, is used in the manufacture of white paint. It is made from ilmenite, FeTiO 3. If 45.1kg of TiO 2 is obtained from 100kg of ilmenite, what is the percentage yield of the conversion? FeTiO 3  TiO 2 1 mole  1 mole 152g  80g 1g  80/152g = g 100kg  52.63kg Percentage yield = 45.1 x 100 = 85.7%

120 Reactions of Carbon Compounds Click to repeat Reactions of Carbon Compounds Click to repeat Reactions of Carbon Compounds Click to return to the Menu Click to End

121 Polymers

122 Addition Polymerisation Many polymers are made from the small unsaturated molecules, produced by the cracking of oil. They add to each other by opening up their carbon to carbon double bonds. This process is called addition polymerisation.

123 Ethene is a starting material of major importance in the petrochemical industry especially for the manufacture of plastics. It is formed by cracking the ethane from the gas fraction or the naphtha fraction from oil. Propene can be formed by cracking the propane from the gas fraction or the naphtha fraction from oil.

124 H C H The ethene is attacked by an initiator (I*) which opens up the double bond I*

125 The ethene is attacked by an initiator (I*) which opens up the double bond I H C C* H Another ethene adds on. H C H

126 The ethene is attacked by an initiator (I*) which opens up the double bond Another ethene adds on. I H C H C C* H Then another H C H

127 The ethene is attacked by an initiator (I*) which opens up the double bond Another ethene adds on. Then another I H C H C H C C* H ….

128 Naming polymers The name of the polymer is derived from its monomer. MONOMERPOLYMER ***ene poly(***ene) ethene poly(ethene) propene poly(propene) styrene poly(styrene) chloroethene poly(chloroethene) tetrafluoroethenepoly(tetrafluoroethene)

129 Repeat Units You can look at the structure of an addition polymer and work out its repeat unit and the monomer from which it was formed. The repeat unit of an addition polymer is always only two carbon atoms long.

130 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 - Repeat Unit CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 - -CH 2 -CHCl -CH 2 -CHCl -CH 2 -CHCl -CH 2 -CHCl - Repeat Unit CH 2 -CHCl -CH 2 -CHCl -CH 2 -CHCl -CH 2 -CHCl -CH 2 -CHCl - Monomer CH 2 =CH 2 Monomer CH 2 =CHCl

131 Condensation Polymers Condensation reactions involve eliminating water when two molecules join. Condensation polymers are made from monomers with two functional groups per molecule.

132 Normally there are two different monomers which alternate in the structure e.g. HH and HOOH

133 The molecules join together, eliminating water as they do so. Hydrogen comes from one molecule. Hydroxide comes from the other molecule. The molecules join where these groups have come off.

134 H H HOOH

135 H H2OH2O HH

136 H H H2OH2OH2OH2O HOOH

137 H H2OH2OH2OH2OH2OH2O HH

138 H H2OH2OH2OH2OH2OH2OH2OH2O H HOOH

139 H H2OH2OH2OH2OH2OH2OH2OH2OH2OH2O

140 Repeat Units You can look at the structure of a condensation polymer and work out its repeat unit and the monomers from which it was formed.

141 -C-(CH 2 ) 4 -C-N-(CH 2 ) 6 -N -C-(CH 2 ) 4 -C-N-(CH 2 ) 6 -N- O O H H O O H H -C-(CH 2 ) 4 -C-N-(CH 2 ) 6 -N- O O H H -C-(CH 2 ) 4 -C-N-(CH 2 ) 6 -N -C-(CH 2 ) 4 -C-N-(CH 2 ) 6 -N- O O H H O O H H HO-C-(CH 2 ) 4 -C-OH O O H-N-(CH 2 ) 6 -N-H H H Polymer Repeat Unit Monomers and

142 Polymer Repeat Unit Monomers and -O-C-C 6 H 4 -C-O-CH 2 -CH 2 -O-C-C 6 H 4 -C-O-CH 2 -CH 2 - O O 0 O HO-CH 2 -CH 2 -OH -O-C-C 6 H 4 -C-O-CH 2 -CH 2 -O-C-C 6 H 4 -C-O-CH 2 -CH 2 - O O 0 O H-O-C-C 6 H 4 -C-O-H O O -O-C-C 6 H 4 -C-O-CH 2 -CH 2 - O O

143 Condensation Polymers Typical condensation polymers are polyesters and polyamides. Terylene is the brand name for a typical polyester.

144 Polyesters As the name suggests polyesters are polymers which use the ester link. The two monomers which are used are a diacid and a diol.

145 The diacid will have a typical structure: The diol will have a typical structure: HOOH They combine like this: C-O-H O H-O-C O C-O-H O H-O-C O

146 The diacid will have a typical structure: The diol will have a typical structure: HOOH They combine like this: C-O-H O H-O-C O C-O-H O H-O-C O HOOH

147 The diacid will have a typical structure: The diol will have a typical structure: HOOH They combine like this: C-O-H O H-O-C O C-O O H-O-C O OH C-O-H O H-O-C O

148 The diacid will have a typical structure: The diol will have a typical structure: HOOH They combine like this: C-O-H O H-O-C O C-O O H-O-C O O C-O-H O -C O HOOH

149 The diacid will have a typical structure: The diol will have a typical structure: HOOH They combine like this: C-O O H-O-C O O C-O O -C O OH C-O-H O H-O-C O

150 Polyesters are manufactured for use as textile fibres and resins. Polyesters used for textile fibres have a linear structure. Cured polyester resins have a three- dimensional structure. Cross linking between the polyester chains makes the structure much more rigid.

151 Amines Amines are a homologous series containing the amine group: N H H

152 The amide link The amide link is formed when an acid and amine join together. N H H HO C O

153 The amide link The amide link is formed when an acid and amine join together. N H H HO C O

154 The amide link The amide link is formed when an acid and amine join together. NHNH C OC O H2OH2O

155 The amide link The amide link is formed when an acid and amine join together. NHNH C OC O The amide link

156 Polyamides A polyamide is made from a diamine and a diacid: H N H N H H diamine C-O-H O H-O-C O diacid They combine like this:

157 H N H N H H C-O-H O H-O-C O

158 H N H N H H H N H NHNH C-O-H O COCO H2OH2O

159 C-O-H O H-O-C O H N H NHNH COCO COCO N H N H H H2OH2O H2OH2O

160 H N H NHNH COCO COCO N H NHNH C-O-H O C O H2OH2O H2OH2O H2OH2O

161 Nylon is a typical polyamide. Nylon is a very important engineering plastic. The strength of nylon is caused by hydrogen bonding between the polymer chains.

162 Synthesis gas Synthesis gas can be obtained by steam reforming of methane from natural gas. CH 4 + H 2 O  CO + 3H 2 It can also be made by the steam reforming of coal.

163 Methanol, used in the production of methanal, is made industrially from synthesis gas. Methanal is an important feedstock in the manufacture of thermosetting plastics. It is used to assist cross-linking so as to make thermosetting plastics and resins.

164 New polymers Kevlar is an aromatic polyamide which is extremely strong because of the way in which the rigid, linear molecules are packed together. These molecules are held together by hydrogen bonds. Kevlar has many important uses.

165 Poly(ethenol) is a plastic which readily dissolves in water. It has many important uses It is made from another plastic by a process known as ester exchange. The percentage of acid groups which have been removed in the production process affects the strengths of the intermolecular forces upon which the solubility depends.

166 Poly(ethyne) can be treated to make a polymer which conducts electricity. The conductivity depends on delocalised electrons along the polymer chain. Poly(vinyl carbazole) is a polymer which exhibits photoconductivity and is used in photocopiers.

167 Biopol is an example of a biodegradable polymer. The structure of low density polythene can be modified during manufacture to produce a photodegradable polymer.

168 Polymers Click to repeat Polymers Click to return to the Menu Click to End

169 Natural Products

170 Fats and Oils Natural fats and oils can be classified according to where they come from: Animal Vegetable Marine

171 Fats and oils in the diet supply the body with energy. They are a more concentrated source of energy than carbohydrates. Oils are liquids and fats are solids. Oils have lower melting points than fats. This is because oil molecules have a greater degree of unsaturation.

172 Saturated fats: have more regular shapes than unsaturated oils:

173 Fat molecules close pack together easily and have a low melting point

174 Oil molecules do not close pack together so easily and have a high melting point

175 Oils can be converted into hardened fats by adding of hydrogen. H2H2 H2H2 H2H2

176 Oils can be converted into hardened fats by adding of hydrogen. This is how margarine is made

177 Fatty acids Fatty acids are straight chain carboxylic acids, containing even numbers of carbon atoms from C 4 to C 24, primarily C 16 and C 18. Fatty acids may be saturated or unsaturated.

178 Fats and oils are esters. They are made from the triol glycerol (propan-1,2,3-triol) CH 2 OH CH OH CH 2 OH glycerol and fatty acids. R C OH O fatty acid

179 Fats and oils are esters. They are made from the triol glycerol (propan-1,2,3-triol) CH 2 OH CH OH CH 2 OH glycerol and fatty acids. fatty acid HO C R O

180 HO C R 3 O CH 2 OH CH OH CH 2 OH HO C R 2 O HO C R 1 O Three fatty acids form esters with the three OH groups of glycerol.

181 C R 3 O CH 2 O CH CH 2 O O C R 2 O C R 1 O Three fatty acids form esters with the three OH groups of glycerol.

182 The hydrolysis of fats and oils produces fatty acids and glycerol in the ratio of three moles of fatty acid to one mole of glycerol. C R O CH 2 O CH CH 2 O O C R O C R O CH 2 OH CH OH CH 2 OH R C OH O + 3

183 Fats and oils Fats and oils consist largely of mixtures of triglycerides. The three fatty acid molecules combined with each molecule of glycerol need not be the same. Soaps are produced by the hydrolysis of fats and oils.

184 Proteins Nitrogen is needed to make protein in plants and animals. Proteins are condensation polymers made up of many amino acid molecules linked together. The structure of the protein is based on the constituent amino acids.

185 Amino acids These are compounds which contain an amine group and an acid group. N H H R HO C C O H

186 There are about 25 essential amino acids. They are different because they have different side groups – shown by “R”. Condensation of amino acids produces the peptide (amide) link. N H H R HO C C O H

187 The peptide link The peptide link is formed when an acid and amine join together. (We have previously called this the amide link.) N H H R 1 HO C C O H N H H R 2 HO C C O H

188 The peptide link The peptide link is formed when an acid and amine join together. (We have previously called this the amide link.) NHNH R 1 HO C C O H N H H R 2 C C O H peptide link

189 Amino acids polymerising N H H R 1 HO C C O H N H H R 2 HO C C O H

190 Amino acids polymerising NHNH R 1 HO C C O H N H H R 2 C C O H H2OH2O N H H R 3 HO C C O H

191 Amino acids polymerising NHNH R 1 HO C C O H NHNH R 2 C C O H H2OH2O N H H R 3 C C O H H20H20 N H H R 4 HO C C O H

192 Amino acids polymerising NHNH R 1 HO C C O H NHNH R 2 C C O H H2OH2O NHNH R 3 C C O H H20H20 N H H R 4 C C O H H2OH2O

193 Building proteins Proteins specific to the body’s needs are built up within the body. The body cannot make all the amino acids required for body. We need protein in our diet to supply certain amino acids known as essential amino acids.

194 Digestion During digestion enzymes hydrolyse the proteins in our diet to produce amino acids. The body then builds up the amino acids it needs from those amino acids.

195 H2OH2O NHNH R 1 HO C C O H NHNH R 2 C C O H NHNH R 3 C C O H N H H R 4 C C O H

196 H2OH2O NHNH R 1 HO C C O H NHNH R 2 C C O H N H H R 3 C C O H N H H R 4 HO C C O H

197 H2OH2O NHNH R 1 HO C C O H N H H R 2 C C O H N H H R 3 HO C C O H N H H R 4 HO C C O H

198 HO N H H R 1 HO C C O H N H H R 2 C C O H N H H R 3 HO C C O H N H H R 4 HO C C O H

199 Hydrolysis The structural formulae of amino acids obtained from the hydrolysis of proteins can be identified from the structure of a section of the protein as shown in the last few slides.

200 Types of proteins Proteins can be classified as fibrous or globular. Fibrous proteins are long and thin and are the major structural materials of animal tissue – muscles, tissues etc.

201 Globular proteins have the spiral chains folded into compact units. Globular proteins are involved in the maintenance and regulation of life processes and include enzymes and many hormones, eg insulin and haemoglobin.

202 Enzymes Enzymes, such as amylase, are biological catalysts An enzyme will work most efficiently within very specific conditions of temperature and pH. The further conditions are removed from the ideal the less efficiently the enzyme will perform.

203 What an enzyme can do is related to its molecular shape. Denaturing of a protein involves physical alteration of the molecules as a result of temperature change or pH change. The ease with which a protein is denatured is related to the fact that enzymes are very sensitive to changes in temperature and pH.

204 Natural Products Click to repeat Natural Products Click to return to the Menu Click to End

205 The End Hope you found the revision useful. Come back soon!!


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