organic and biological chemistry
DESCRIPTION
Organic and Biological Chemistry . 4.10 Triglycerides. Triglycerides. Fats and oils from plants and animals Tri-esters of propan-1,2,3-triol (glycerol) Three long straight chain carboxylic acids (fatty acids) form ester linkages with each glycerol molecule. Carboxylic acid. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/1.jpg)
Organic and Biological Chemistry 4.10 Triglycerides
1
![Page 2: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/2.jpg)
TriglyceridesFats and oils from plants and animalsTri-esters of propan-1,2,3-triol (glycerol)Three long straight chain carboxylic acids
(fatty acids) form ester linkages with each glycerol molecule
2
![Page 3: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/3.jpg)
Triglycerides
3
C
H
H
OH C
H
O
H
C
H
H
O H
C
H
H
OH C
H
O
H
C
H
H
O H
Propan-1,2,3-triol
R C
O
O
H
R C
O
O
H
Carboxylicacid
![Page 4: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/4.jpg)
4
![Page 5: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/5.jpg)
5
![Page 6: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/6.jpg)
TriglyceridesFatty acids contain an even
number of carbon atoms (between 12 and 20). The carbon chain can be saturated or unsaturated.
If there is more than 1 double bond the molecule is referred to as polyunsaturated
Naturally occurring tri-esters of propan-1,2,3-triol generally will contain three different fatty acids
6
![Page 7: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/7.jpg)
Examples of Fatty Acids
7
![Page 8: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/8.jpg)
8
Oleic Acid
![Page 9: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/9.jpg)
9
Olive Oil
![Page 10: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/10.jpg)
Triglycerides
10
Triglycerides can be hydrolysed to produce glycerol and three fatty acid molecules.
In biological organisms that can utilise triglycerides for energy this reaction is catalysed by lipase enzymes
In the laboratory concentrated acid or alkali combined with heating can be used to break down the triglyceride
![Page 11: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/11.jpg)
TriglyceridesThe state of an edible fat or oil at room
temperature can be used to determine its source.
Edible fats are solids at 25oC and generally are obtained from land animals
Edible oils are liquids at 25oC and are obtained from plants or marine animals
11
![Page 12: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/12.jpg)
TriglyceridesMelting points of fats and oilsAs the length of the carbon chain increases
so does the tm increase, due to increased dispersion forces.
As the degree of unsaturation increases (i.e. number of C=C bonds increases) the tm
decreases. The molecules can’t pack together as closely and so don’t solidify
Fat contains a greater percentage of saturated fatty acids than unsaturated fatty acids and as a result it is solid at room temperature
Oils contain a greater percentage of unsaturated fatty acids and are liquids
12
![Page 13: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/13.jpg)
13
![Page 14: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/14.jpg)
Reactions of TriglyceridesThe degree of unsaturation of a
triglyceride can be determined by its reaction with bromine or iodine
C
H
H
C
H
H
C
H
H
C
H
H
+
Br Br
Br Br
C
H
H
Br C
H
H
Br
C
H
H
Br C
H
H
Br
14
This is referred to as an Addition reaction
The orange colour of the bromine disappears as the reaction occurs. (The products are colourless)
To enable the bromine to mix with the triglyceride both the bromine and triglyceride are dissolved in a non polar solvent (cyclohexane)
![Page 15: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/15.jpg)
Reactions of TriglyceridesBy titrating a standard solution of bromine
(burette) with a known volume of a standard solution of fat or oil the degree of unsaturation can be measured.
The greater the amount of bromine required the greater the degree of unsaturation.
The end point is indicated by the first permanent orange colour in the flask.
15
![Page 16: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/16.jpg)
Reactions of TriglyceridesIodine numberThe degree of unsaturation of a fat
or oil is often described in terms of the iodine number
The iodine number is the mass of iodine that reacts with 100g of the fat or oil
The greater the iodine number the greater the degree of unsaturation
16
Olive oil Iodine Number =75–94 (virgin and refined)
![Page 17: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/17.jpg)
Reactions of TriglyceridesLiquid oils can be converted to solid fats by
catalytic hydrogenationThe vegetable oil is heated with hydrogen gas
under pressure in the presence of a nickel catalyst. These conditions increase the rate of reaction.
Sufficient hydrogen is added to produce a product that is solid at room temperature
17
C
H
H
C
H
H
C
H
H
C
H
H
+
H H
H H
Ni High PNi
Ni
High P
High P
C
H
H
H C
H
H
H
C
H
H
H C
H
H
H
![Page 18: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/18.jpg)
Organic and Biological Chemistry
4.11 Carbohydrates
18
![Page 19: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/19.jpg)
CarbohydratesGeneral formula is usually CxH2yOy
This can often be written as Cx(H2O)y
Carbohydrates are polyhydroxyaldehydes or polyhydroxyketones or compounds that produce these when hydrolysed
Can be monosaccharides, disaccharides or polysaccharides depending on the number of simple sugars in the molecule
19
![Page 20: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/20.jpg)
MonosaccharidesMonomersGeneral formula CxH2xOx where x = 3 to 8Water soluble (Hydrogen bond with water)Simple sugars eg. Glucose, FructoseSolids at room temperatureSweet
20
![Page 21: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/21.jpg)
GlucoseC6H12O6
Can exist as a chain or ring structureThese structures are in equilibrium in
aqueous solution
21
D-Glucose α-D-Glucose
![Page 22: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/22.jpg)
22
![Page 23: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/23.jpg)
GlucoseIn the chain form the aldehyde can be
oxidised by Tollen's reagent forming the silver mirror and the carboxylate ion but there is no reaction with the ring form
23
H O C
H
H
C
H
O
H
C
H
O
H
C
O
H
H
C
H
O
H
C
O
H
H O C
H
H
C
H
O
H
C
H
O
H
C
O
H
H
C
H
O
H
C
O
H
TollensTollens
Tollens
H O C
H
H
C
H
O
H
C
H
O
H
C
O
H
H
C
H
O
H
C
O
O–
H O C
H
H
C
H
O
H
C
H
O
H
C
O
H
H
C
H
O
H
C
O
O–
This reaction causes the equilibrium to favour the formation of the chain structure
![Page 24: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/24.jpg)
DisaccharidesTwo monosaccharides per moleculeFormed by a condensation reaction
(eliminating water)Can be hydrolysed to form
monosaccharidesWater soluble compounds (Hydrogen bond
with water)
24
![Page 25: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/25.jpg)
25
Sucrose
Lactose
Maltose
![Page 26: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/26.jpg)
PolysaccharidesLarge polymers of monosaccharidesFormed by condensation reaction and
broken down to monosaccharides by hydrolysis
(C6H10O5)n +½nH2O ½nC12H22O11
polysaccharide disaccharideC12H22O11 + H2O 2C6H12O6
disaccharide monosaccharideOverall(C6H10O5)n + nH2O nC6H12O6
26
![Page 27: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/27.jpg)
PolysaccharidesInsoluble in water. Although hydrogen
bonding can occur the large molecular size prevents mixing with water
Will absorb water
27
![Page 28: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/28.jpg)
PolysaccharidesCelluloseStructural material in plantsMade up of approx. 3000 glucose unitsStraight chain polymer
28
![Page 29: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/29.jpg)
PolysaccharidesStarchMade up of amylose 250-2000 glucose
units in a straight chain and amylopectin which contains hundreds of thousands of glucose in a branched chain structure.
29
![Page 30: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/30.jpg)
30
AmyloseAmylopectin
![Page 31: Organic and Biological Chemistry](https://reader037.vdocuments.site/reader037/viewer/2022103008/56815fdd550346895dcee6ff/html5/thumbnails/31.jpg)
PolysaccharidesGlycogenStorage molecule for glucose in liver and
muscleBranched chain polymer
31