classification, trans fatty acids, the essential fatty acids, their role in CHD

1. 11
FATTY ACIDSFATTY ACIDS

2. 22
Learning objectives
 The two basic components of fatty acids &
their groups on the basis of number of carbon
atoms in fatty acid.
 Essential and non-essential fatty acids.
 The well known examples of saturated &
unsaturated fatty acids.
 Preparation of fatty acid in vitro.

3. 33
Fatty acidsFatty acids
 Fatty acids are the mostFatty acids are the most important componentimportant component
of theof the lipidslipids..
 These are water insoluble,These are water insoluble, long chainlong chain
hydrocarbonshydrocarbons havinghaving carboxyl groupcarboxyl group (COOH)(COOH)
on one end &on one end & methylmethyl (CH3)(CH3) group on the othergroup on the other
end of the chain.end of the chain.
 Fatty acids in human body are of great variety.Fatty acids in human body are of great variety.
 All fatty acids areAll fatty acids are building blocksbuilding blocks ofof lipidslipids
includingincluding neutral fatsneutral fats,, phospholipidsphospholipids,,
glycolipidsglycolipids,, cholesterolcholesterol,, waxeswaxes etc.etc.

4. 44
 Fatty acids havingFatty acids having carboncarbon atom fromatom from
1 – 121 – 12 are calledare called short chainshort chain fatty acids.fatty acids.
13 – 1813 – 18 areare moderate chainmoderate chain FAs.FAs.
19 – onward long chain19 – onward long chain FAs.FAs.
 In the bodyIn the body short chainshort chain FA with 2 C are inFA with 2 C are in
abundanceabundance & with 4, 6 & 8 are present in very& with 4, 6 & 8 are present in very
small amount.small amount.
 Moderate chainModerate chain FAs areFAs are also abundancealso abundance inin
human body fluid, most frequent ishuman body fluid, most frequent is 16 C16 C
((Palmitic acidPalmitic acid).).

5. 55
Classification of fatty acidsClassification of fatty acids
 Fatty acids are classifiedFatty acids are classified accordingaccording to theto the
number of carbonnumber of carbon atoms & presence oratoms & presence or
absence ofabsence of double bonddouble bond etc.etc.
1-1- Saturated acids.Saturated acids.
2-2- Unsaturated acids.Unsaturated acids.
3-3- Branched chain acids.Branched chain acids.
4-4- Cyclic acids.Cyclic acids.
5-5- Hydroxy & keto-derivatives.Hydroxy & keto-derivatives.

6. 66
1- Saturated Acids1- Saturated Acids
 These are the fatty acids whichThese are the fatty acids which contain singlecontain single
bonds,bonds, there will bethere will be nono anyany double bonddouble bond..
 Usually containUsually contain even numbereven number of C atoms.of C atoms.
 SomeSome FAsFAs with odd number of C atoms havewith odd number of C atoms have
also been discovered in plants & animal fats.also been discovered in plants & animal fats.
 AA few typical FAsfew typical FAs obtained from different fatsobtained from different fats
are given along with sources.are given along with sources.

7. 77
NameName FormulaFormula SourceSource
 i- Butyric acidi- Butyric acid-4-4 CHCH33 (CH(CH22))22 COOH ButterCOOH Butter
 ii- Caproic acidii- Caproic acid-6-6 CHCH33 (CH(CH22))44 COOH ButterCOOH Butter
 iii- Caprylic acidiii- Caprylic acid-8-8 CHCH33 (CH(CH22))66 COOH ButterCOOH Butter
 iv- Capric acidiv- Capric acid-10-10 CHCH33 (CH(CH22))88 COOH Butter,COOH Butter,
coconut oilcoconut oil
 v- Lauric acid CHv- Lauric acid CH33 (CH(CH22))1010COOH SpermacetiCOOH Spermaceti
 vi-vi- Myristic acidMyristic acid CHCH33 (CH(CH22))1212COOH ButterCOOH Butter
 vii-vii- Palmitic acidPalmitic acid CHCH33 (CH(CH22))1414COOH animal &COOH animal &
vegetable fatsvegetable fats
 viii-viii- Stearic acidStearic acid CHCH33 (CH(CH22))1616COOH =COOH =
 All above acids contain even number of carbon atomsAll above acids contain even number of carbon atoms

8. 88
 Non essential fatty acids:Non essential fatty acids:
 FromFrom dietarydietary point of view,point of view, saturated FAssaturated FAs areare
synthesizedsynthesized by human body,by human body, no needno need toto
provide asprovide as externalexternal source & not so essentialsource & not so essential
as unsaturated FAs.as unsaturated FAs.
 So they are called non-essential fatty acids.So they are called non-essential fatty acids.

9. 99
2- Unsaturated Fatty acids2- Unsaturated Fatty acids
 These containThese contain one or more double bondsone or more double bonds & are& are
moremore reactivereactive than saturated fatty acids.than saturated fatty acids.
 They are furtherThey are further classifiedclassified in toin to
 A)- One Double Bond acids (mono-enoic)A)- One Double Bond acids (mono-enoic)
 i- Palmitoleic acids:i- Palmitoleic acids: CC1515HH2929COOHCOOH
CHCH33 (CH(CH22))55 CH= CH (CHCH= CH (CH22))77 COOHCOOH
Source;Source; Animal & vegetable fats & oils.Animal & vegetable fats & oils.

10. 1010
 ii- Oleic acid:ii- Oleic acid: CC1717HH3333COOHCOOH
 CHCH33 (CH(CH22))77 CH= CH (CHCH= CH (CH22))77COOHCOOH
 Animal & vegetable fats & oilsAnimal & vegetable fats & oils
 iii- Erucic acid:iii- Erucic acid: CC2121HH4141COOHCOOH
 CHCH33 (CH(CH22))77 CH= CH (CHCH= CH (CH22))1111COOHCOOH
 Rapeseed oilRapeseed oil

11. 1111
 B)- Two Double Bond Acids (Di-enoic)B)- Two Double Bond Acids (Di-enoic)
 Linoleic acidLinoleic acid – C– C1717HH3131COOHCOOH
 CHCH33(CH(CH22))44CH=CHCHCH=CHCH22 – CH=CH(CH– CH=CH(CH22))77COOHCOOH
 Source;Source; Linseed & cotton seed oil.Linseed & cotton seed oil.
 C)- Three Double Bond Acids (Tri-enoic)C)- Three Double Bond Acids (Tri-enoic)
 Linolinic acidLinolinic acid – C– C1717HH2929COOHCOOH
 CHCH33CHCH22CH=CHCHCH=CHCH22CH=CHCHCH=CHCH22CH=CH(CHCH=CH(CH22))77COOHCOOH
 Linseed oil.Linseed oil.

12. 1212
 D)- Four Double Bond AcidsD)- Four Double Bond Acids
 Archidonic acid:Archidonic acid: CC1919HH3131COOHCOOH
 CHCH33(CH(CH22))44CH=(CHCHCH=(CHCH22CH=)CH=)33CH(CHCH(CH22))33COOHCOOH
 Animal and plant source.Animal and plant source.
 Essential Fatty Acids:Essential Fatty Acids:
 FromFrom dietarydietary point of view, unsaturated fattypoint of view, unsaturated fatty
acids must beacids must be taken by humantaken by human ((externalexternal
sourcesource) because these can) because these can notnot bebe synthesizedsynthesized
in the body.in the body.
 So they are very essential – called essential FASo they are very essential – called essential FA

13. 1313
3- Branched Chain Fatty acids3- Branched Chain Fatty acids
 Branched chain FA are often present inBranched chain FA are often present in waxeswaxes
than fat.than fat.
 These areThese are
 i. Isoseriesi. Isoseries
 CHCH33
 CH – (CHCH – (CH22)n – COOH)n – COOH
 CHCH33

14. 1414
 ii. Anti-isoseriesii. Anti-isoseries
 (CH(CH22)n – COOH)n – COOH
 CHCH33 – CH– CH22 – CH– CH
 CHCH33

15. 1515
4- Cyclic Fatty acids4- Cyclic Fatty acids
 Fatty acids having cyclic structure areFatty acids having cyclic structure are rarerare butbut
have been identified to behave been identified to be presentpresent in certainin certain
seeds oilsseeds oils..
 Ring structure is present at theRing structure is present at the endend ofof FAFA
chainchain
 CH = CHCH = CH
 HH22C CH(CHC CH(CH22))1212COOHCOOH

CHCH22 Tridecanoic acidTridecanoic acid

16. 1616
5- Hydroxy & Keto derivatives5- Hydroxy & Keto derivatives
 The hydroxy derivatives of C2, C3, & C4 FAThe hydroxy derivatives of C2, C3, & C4 FA
do not exist in lipids.do not exist in lipids.
 Many hydroxy derivatives of higher acids areMany hydroxy derivatives of higher acids are
known.known.

17. 1717
Preparation of Fatty acidsPreparation of Fatty acids
 All the acids are obtained by theAll the acids are obtained by the hydrolysishydrolysis ofof
estersesters with super heatedwith super heated steamsteam oror alkalialkali..
 TheThe saltsalt obtained isobtained is treatedtreated with somewith some mineralmineral
acidacid to get the acid.to get the acid.
 OO
 CHCH22 – O – C – R CH– O – C – R CH22OH OOH O
 OO
 CH – O – C – R + 3HCH – O – C – R + 3H22O CHOH + 3R – C – OHO CHOH + 3R – C – OH
 OO
 CHCH22 – O – C – R CH– O – C – R CH22OHOH

18. 1818
PHYSICAL PROPERTIES OF FATTY ACIDSPHYSICAL PROPERTIES OF FATTY ACIDS
 1- Physical state & Melting point1- Physical state & Melting point::
 The melting of FAsThe melting of FAs dependsdepends upon theupon the chainchain
lengthlength && degree of unsaturationdegree of unsaturation..
 Chain length:Chain length: TheThe longerlonger is the chain , theis the chain , the
higherhigher is MP & vice versa.is MP & vice versa.
 e.g. The MP of Butyric acid is -8C whilee.g. The MP of Butyric acid is -8C while
Palmitic acid is 62C & Stearic acid is 70C.Palmitic acid is 62C & Stearic acid is 70C.

19. 1919
 Unsaturation:Unsaturation: TheThe greatergreater thethe numbernumber ofof
double bonds, thedouble bonds, the lowerlower the MP.the MP.
 e.g. the MP of Oleic acid is 14C whilee.g. the MP of Oleic acid is 14C while
Linolenic acid have -10C.Linolenic acid have -10C.
 That is why theThat is why the acids withacids with small chainsmall chain lengthlength
& with& with high unsaturationhigh unsaturation are generallyare generally liquidsliquids
at room temperature.at room temperature.

20. 2020
 2- Isomerism of Fatty acids:2- Isomerism of Fatty acids:
 TheThe unsaturatedunsaturated FAs containingFAs containing double bondsdouble bonds
show geometrical isomerism.show geometrical isomerism.
 Cis Isomer:Cis Isomer: Oleic acid is a cis acidOleic acid is a cis acid both chainboth chain
on theon the same sidesame side..
 CHCH33(CH(CH22))77 – C – H– C – H
 HOOC(CHHOOC(CH22))77 – C – H– C – H
 cis form (oleic acid)cis form (oleic acid)

21. 2121
 Trans Isomer:Trans Isomer: trans isomer is called elaidictrans isomer is called elaidic
acid,acid, both chainsboth chains are onare on oppositeopposite direction.direction.
 H – C – (CHH – C – (CH22))77CHCH33
 HOOC(CHHOOC(CH22))77 – C – H– C – H
 3- Solubility3- Solubility
 Also depends upon theAlso depends upon the chain lengthchain length & degree& degree
ofof unsaturationunsaturation..
 Chain length:Chain length: solubility of FAssolubility of FAs decreasesdecreases
withwith increaseincrease in chain length. e.g. Butyric acidin chain length. e.g. Butyric acid
is more soluble than palmitic acid.is more soluble than palmitic acid.

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 Degree of unsaturation:Degree of unsaturation: solubility of FAssolubility of FAs
increasesincreases withwith increaseincrease in double bond.in double bond.
 e.g. palmitoleic acid is more soluble thane.g. palmitoleic acid is more soluble than
palmitic acid.palmitic acid.
 4- Boiling Point4- Boiling Point
 The boiling points of FAsThe boiling points of FAs increasesincreases with thewith the
increaseincrease in chain length.in chain length.

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 5- Absorption Spectra5- Absorption Spectra
 TheThe naturallynaturally occurring FAsoccurring FAs do not absorbdo not absorb
light in UV/visible region.light in UV/visible region.
 Conjugated doubleConjugated double bonds show an appreciablebonds show an appreciable
absorptionabsorption in UV/visible region (230-260nm).in UV/visible region (230-260nm).
 ThusThus spectroscopic analysisspectroscopic analysis is helpful in theiris helpful in their
characterizationcharacterization..

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CHEMICAL PROPERTIES OF FATTY ACIDSCHEMICAL PROPERTIES OF FATTY ACIDS
 1- Salt Formation1- Salt Formation
 Fatty acids whenFatty acids when reactedreacted withwith alkaliesalkalies formform
their salts.their salts.
R – COOH + HO Na R – COONa+ HR – COOH + HO Na R – COONa+ H22OO
 Soap:Soap: Metallic saltsMetallic salts of higher FAs are calledof higher FAs are called
soapsoap..
 These may be salts of Na, K, Mg & Ca.These may be salts of Na, K, Mg & Ca.
 Na & K salts are solubleNa & K salts are soluble & are good& are good
emulsifyingemulsifying agents, While Ca or Mg salts areagents, While Ca or Mg salts are
insoluble in water.insoluble in water.

25. 2525
 2- Detergent Formation2- Detergent Formation
 ReductionReduction of COOH group of FAs producesof COOH group of FAs produces
alkyl alcoholsalkyl alcohols, which can be, which can be sulphatedsulphated oror
sulphonated to form alkyl sulphates orsulphonated to form alkyl sulphates or
sulphonates which act assulphonates which act as detergentdetergent..

 R – COOH + 2HR – COOH + 2H22 R – CHR – CH22OH + HOH + H22OO
 R – CHR – CH22OH + Na R – CHOH + Na R – CH22 – ONa R – CH– ONa R – CH22 – SO– SO22ONaONa
 Sod alkyl sulphonateSod alkyl sulphonate
 Unlike soaps the detergents are stable & do notUnlike soaps the detergents are stable & do not
form insoluble salts with Ca & Mg.form insoluble salts with Ca & Mg.

26. 2626
 3- Ester Formation3- Ester Formation
 Fatty acids form esters whenFatty acids form esters when treatedtreated withwith
alcoholsalcohols in the presence of dehydrating agentsin the presence of dehydrating agents
likelike conc. Hconc. H22SOSO44 oror anhydrous HClanhydrous HCl..

 R – COOH + HO – R R – C O– OR + H2OR – COOH + HO – R R – C O– OR + H2O
 Most important esters are withMost important esters are with glycerolglycerol..
 Mono, di, triMono, di, tri glyceridesglycerides are theare the essentialessential
constituentsconstituents of fats & oils.of fats & oils.

27. 2727
 4- Hydrogenation4- Hydrogenation
 Unsaturated acidsUnsaturated acids areare hydrogenatedhydrogenated in thein the
presence of Pt, Ni or Cu.presence of Pt, Ni or Cu.
 Raney nickleRaney nickle is of commercial importance foris of commercial importance for
the manufacture ofthe manufacture of vegetable fatsvegetable fats fromfrom oilsoils..

 CHCH33(CH(CH22))77CH=CH(CHCH=CH(CH22))77COOH CHCOOH CH33(CH(CH22))1616COOHCOOH
 Oleic acid Stearic acidOleic acid Stearic acid
H2
Ni

28. 2828
 5- Addition of Halogen:5- Addition of Halogen:
 Halogen under mild condition readilyHalogen under mild condition readily add toadd to
double bonddouble bond..
 TheThe orderorder of reactivity isof reactivity is FF22>Cl>Cl22>Br>Br22>I>I22..
 Elaidic & oleic acids yieldElaidic & oleic acids yield differentdifferent
dibromides.dibromides.
 With oleic acid the bromine atoms will be onWith oleic acid the bromine atoms will be on
the same sidethe same side (erythro form)(erythro form) & with elaidic& with elaidic
acid on opposite sidesacid on opposite sides (threo form)(threo form)..

29. 2929
 BrBr22
 CHCH33(CH(CH22))77CH=CH(CHCH=CH(CH22))77COOHCOOH
 Oleic acid Br BrOleic acid Br Br
 CHCH33(CH(CH22))77CHCH(CHCHCH(CH22))77COOHCOOH
 erythro formerythro form

30. 3030
 6- Formation of prostaglandin:6- Formation of prostaglandin:
 Prostaglandins are synthesizeProstaglandins are synthesize withinwithin the bodythe body
fromfrom unsaturated fatty acidsunsaturated fatty acids & have been& have been
found to occur infound to occur in many organsmany organs..
 e.g. seminal plasma, genital glands.e.g. seminal plasma, genital glands.
 They play aThey play a hormonal rolehormonal role & thus control& thus control
different biological phenomenon.different biological phenomenon.
 OHOH
 - CH- CH22(CH(CH22))55COOHCOOH
 - CH=CH – CH(CH- CH=CH – CH(CH22))44CHCH33
 OO PGE1PGE1

31. 3131
 Smooth musclesmuscles contraction.
 Labour inducingLabour inducing agent.
 Involved in blood clottingblood clotting.
 Mucosal protectiveprotective agent.

32. 3232
 7- Rancidation:7- Rancidation:
 AdditionAddition of Oof O22 on double bond giveson double bond gives
peroxidesperoxides..
 Peroxides can undergoPeroxides can undergo cleavagecleavage to formto form badbad
smellingsmelling aldehyde, ketonses & acids.aldehyde, ketonses & acids.
 Thus onThus on exposure to airexposure to air, light & warmth, fats, light & warmth, fats
undergoundergo autoxidationautoxidation. The process is known as. The process is known as
rancidationrancidation which is prevented by vitamin E.which is prevented by vitamin E.
 O2O2

CHCH33(CH(CH22))77CH=CH(CHCH=CH(CH22))77COOHCOOH CHCH33(CH(CH22))77CHO +CHO +
 COOH(CHCOOH(CH22))77COOHCOOH

33. 3333
Lecture - feedback
 Define lipids?
 Fatty acids are the building block of……..?
 Palmitic acid is ………..carbon fatty acid?
 FromFrom dietarydietary point of view, unsaturated fatty acidspoint of view, unsaturated fatty acids
are ……?are ……?
 All FAs are obtained by theAll FAs are obtained by the hydrolysishydrolysis of ….. withof ….. with
super heatedsuper heated steamsteam oror alkalialkali??
 TheThe longerlonger is the chain , the …….. the MP?is the chain , the …….. the MP?
 Elaidic acid is a trans or cis isomer of oleic acid?Elaidic acid is a trans or cis isomer of oleic acid?
 The commercial manufacturing of vegetable fat byThe commercial manufacturing of vegetable fat by
the method ….…?the method ….…?
 The process of auto oxidation of fat called…..?The process of auto oxidation of fat called…..?

34. 3434
 References and keys:References and keys:
 Dr.M.Rafiq, and Muashtaq Ahmad.Dr.M.Rafiq, and Muashtaq Ahmad.
 RapeseedRapeseed = oil seed plant of mustard family -Brasica napus= oil seed plant of mustard family -Brasica napus
 SpermacetiSpermaceti == waxy solid from sperm whales: a white waxy solid. Source: oil inwaxy solid from sperm whales: a white waxy solid. Source: oil in
the head of sperm whales and other cetaceans.the head of sperm whales and other cetaceans.
 Raney nickleRaney nickle = special form of nickel prepared by treating Al – Ni alloy with= special form of nickel prepared by treating Al – Ni alloy with
NaOH sol. Nickel is left in the form of spongy mass which is more powerfulNaOH sol. Nickel is left in the form of spongy mass which is more powerful
catalyst especially for hydrogenation.catalyst especially for hydrogenation.