EFN-313 Lífræn efnafræði

11. kafli

“The most important hypothesis in all of

biology…is that everything that animals do,atoms do. In other words, there is nothingthat living things do that cannot be understood from the point of view that they are made of atoms acting according to the laws of physics.”

Richard Feynman (1918-1988)

Lífræn efni byggjast öll á kolefni

• C, CO, CO2 og CO3 teljast ólífræn

• Önnur C sambönd kallast lífræn

• Annaðhvort sameindir eða sameindajónir

• Óendanlega mörg lífræn efni til, á öllum formum með mismunandi eiginleika.

C-atóm eru einstök

• Mynda óskautað samgild tengi við Vetni

• Mynda samgild tengi sín á milli og mynda langar keðjur

• Mynda samgild tengi við aðra málmleysingja t.d. P,O,N,S og halogena

• C-C og C-H tengi eru óskautuð (nonpolar)

Fjögur sp3 hybridised orbitals mynda ferflötung

sp3 hybridised orbitals frá 2 C atómum geta skarast og myndað C-C σ-tengi

C-C bond

Each sp3 orbital

contributes one electron

to form C-C [C..C]

Raun lögun etan sameindar

sp3 svigrúmablanda (rafeindir) flýr eins langt frá kjarnanum og hægt er og tengist í þær áttir.

Carbon sp3 orbitals can overlap with Hydrogen 1s orbitals to

form Carbon-Hydrogen bonds

HC C

HH

H

H

H=

bonds: symmetrical about the bond axis

Each sp3 orbital contributes one electron; each s orbital

contributes one electron to form C-H [C..H]

C-C N-N O-O

Bond Dissociation Energy(kJ mol-1) 348 163 157

•Carbon-Carbon bonds: especially Sterk samgild tengi

•Kolefni: Einstakt, myndar catenate [Keðjur]

•Forms molecules composed of C-C bonds

CC

CC

CC

C CC

CC

C

C

C

C

C C

CC

Línulaga/Linear Greinótt/Branched Hring/Cyclic

•Organic molecules = Carbon-based molecules

•Organic chemistry = Chemistry of carbon-based molecules

Some properties of organic molecules

•Stability: composed of stable C-C covalent bonds

•Defined molecular structures

•Defined three-dimensional shapes

Organic chemicals are universal

OrganicOrganicChemicalsChemicals

Biological matter•Plants•Animals•Microbes

Geological matter•Fossil Fuels•Other

Atmosphericand

cosmic matter

Manufacturedproducts

Biological organic chemicals

• Sugars• Proteins• Fats & oils• Vitamins• DNA & RNA• Wood• Natural rubber• Essential oils

• Natural fibres• Antibiotics• Fermentation

products• Natural flavours• Natural

fragrances• Plant & microbial

products• Bio-matter

Organic chemicals in manufactured products

Bio-activeproducts

Medicines Veterinary medicines

Herbicides

Pesticides

Fungicides

Plant growth hormones

Imaging agents

Fertilizers

Antiseptics

Disinfectants

Organic chemicals in manufactured products

Materials

Fibres & clothings

Plastics

Coatings & lacquers

Packaging

Paper

Films

Medical implants

Wound dressings

Organic chemicals in manufactured products

FoodsSugars

Fats & Oils

Anti-oxidantsColourants

Flavourings

Vitamins

Dietary supplements

Fibre

Fuels

“Petrol”

“Diesel”

LPG

Natural gas

Coal

Peat/Turf

Methanol/Ethanol

Organic chemicals in manufactured products

Miscellaneous• Lubricants• Cosmetics• Fragrances• Pigments• Dyes• Inks• Adhesives• Explosives

• Detergents• Surfactants• Emulsifiers• Coolants• Photographic agents• Anti-scalants• Forensic chemicals• Liquid crystal displays

Hydrocarbons - Kolvetni

• Kolvetni eru einföldustu lífrænu efnin

• Kolvetni eru gerð úr Kolefni og Vetni

• Kolvetni þar sem öll tengi milli atóma eru einföld kallast ALKANar

• Öll eintengi eru sigmatengi (σ-bonds) og um þau frjás snúningur.

• Einföldustu: CH4, C2H6, C3H8

Um kolvetni

• Mettað kolvetni (Saturated hydrocarbon):Mettað kolvetni (Saturated hydrocarbon): Kolvetni eingöngu með eintengi

• Alkane:Alkane: Mettuð kolvetni þar sem kolefnin raða sér í opna keðju.

• Aliphatic hydrocarbon:Aliphatic hydrocarbon: Annað nafn á alkan

Hydrocarbons

H-C C-HH-C-C-H

H

H

H

H HC C

H

H H

Hydrocarbons

Alkanes(Chapter 2)

Alkenes(Chapters 5-6)

Alkynes(Chapter 7)

Arenes(Chapter 21-22)

Only carbon-carbon single

bonds

One or more carbon-carbondouble bonds

One or morecarbon-carbontriple bonds

One or morebenzenelike

rings

Class

Example

Carbon-carbon

bonding

Name Ethane Ethene Acetylene Benzene

Saturated Unsaturated

Bygging

• Lögun– Ferflötungslaga– Öll horn tengja um 109.5°

Drawing Alkanes

• Nokkrar aðferðir við að teikna byggingu– Endi og horn eru kolefnisatóm (line-angle)

CH3CH2CH2CH3CH3CH2CH3 CH3CH2CH2CH2CH3

PentaneButanePropane PentanePropane

Structuralformula

Line-angle formula

Ball-and-stickmodel

IUPAC

• International Union of Pure and Applied Chemistry

• Látum nægja að læra utanað upp í 10 en allt ofar þarf að kannast við.

• Sjá annars töflu 11.1 í bók.

Línulaga - Beinkeðjualkanar

Nafn # Kolefni Byggingaformúla

Methane 1 CH4

Ethane 2 CH3CH3

Propane 3 CH3CH2CH3

Butane 4 CH3CH2CH2CH3

Pentane 5 CH3CH2CH2CH2CH3

IUPAC NAMES

Nafn # C-atóma Byggingaformúla

Hexane 6 CH3CH2CH2CH2CH2CH3

Heptane 7 CH3CH2CH2CH2CH2CH2CH3

Octane 8 CH3CH2CH2CH2CH2CH2CH2CH3

Nonane 9 CH3 CH2 CH2CH2CH2CH2CH2CH2CH3

Decane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

Dæmi

A. Hver er byggingaformúla… H H H H

H C C C C H

H H H H

B. Hver er mólikúlformúlan?C. Hvert er nafnið?

Lausn

A. CH3CH2CH2CH3

B. C4H10

C. butane

Nafnakerfi - IUPAC

• Forskeyti/Prefix segir fjölda C-atóma

undec-dodec-

tetradec-pentadec-hexadec-heptadec-

nonadec-eicos-

tridec-

11121314151617

octadec- 181920

Prefixmeth-eth-prop-but-pent-hex-

oct-non-dec-

1234567hept-89

10

Carbons CarbonsPrefix

Nöfn: Greinóttra alkana1. Finndu lengstu kolefniskeðjuna.2. Númera keðjuna, byrja þaðan sem

styst er í fyrstu hliðargrein.3. Nefnið hliðarhópa og notið númer á C

sem staðsetningu.4. Raðið hliðarhópum (substituents) í

stafrófsröð.5. Notið di-, tri-, ef sami hópur kemur oft

fyrir.

Lengsta keðjan

6. Fjöldi kolefnisatóma í lengstu keðju ræður orðstofni/Nafni

7. Ef það eru tvær keðjur jafnlangar velst sú keðja sem hefur fleiri hliðarhópa.

C

CH3

CH2

CH3

CH CH2 CH2 CH3

CH CH2 CH3H3C

H3C

=>

Númera C -atóm

• Byrjið við endann næst fyrsta hliðarhóp.

• Ef tveir hl.hópar eru jafn langt frá skoðið þá aðra hópa.

1

2

3 4 5

6 7CHH3C

CH3

CH

CH2CH3

CH2 CH2 CH

CH3

CH3

=>

Nöfn hliðarhópa – ALKYL hópar

• CH3-, methyl

• CH3CH2-, ethyl

• CH3CH2CH2-, n-propyl

• CH3CH2CH2CH2-, n-butyl

CH3 CH CH2 CH3

sec-butyl

CH3 CH

CH3

CH2

isobutyl

CH3 CH CH3

isopropyl

CH3C

CH3

CH3

tert-butyl

=>

Alphabetize

• Raðið í stafrófsröð.

• Ignore di-, tri-, í stafrófsröðinni.

CHH3C

CH3

CH

CH2CH3

CH2 CH2 CH

CH3

CH3

3-ethyl-2,6-dimethylheptane =>

Flóknari hliðarhópar• Ef greinin er greinótt, númerið C in frá tengi

við aðalkeðju.• Nefnið og númerið hliðarkeðju í hliðarkeðju.

• Setjið sviga utanum flókna hliðarhópinn.

12

31-methyl-3-(1,2-dimethylpropyl)cyclohexane =>

Nomenclature - IUPAC

• Parent name:Parent name: the longest carbon chain• Substituent:Substituent: a group bonded to the parent chain

– alkyl groupalkyl group:: a substituent derived by removal of a hydrogen from an alkane; given the symbol R-

Alkane Alkyl group

CH4

Name Name

Methane CH3- Methyl group

CH3CH3 Ethane CH3CH2- Ethyl group

Nomenclature - IUPAC1.The name of a saturated hydrocarbon with an

unbranched chain consists of a prefix and suffix

2. The parent chain is the longest chain of carbon atoms

3. Each substituent is given a name and a number

4. If there is one substituent, number the chain from the end that gives it the lower number

CH3CHCH3

CH3

2-Methylpropane

12 3

CH3CH2CH2CHCH3

CH3

2-Methylpentane

123

45 5

432

1

(not 4-methylpentane)

Nomenclature - IUPAC

5. If there are two or more identical substituents, number the chain from the end that gives the lower number to the substituent encountered first

– indicate the number of times the substituent appears by a prefix di-, tri-, tetra-, etc.

– use commas to separate position numbers

2,4-Dimethylhexane1

23

45

66

54

32

1

(not 3,5-dimethylhexane)

Nomenclature - IUPAC

6. If there are two or more different substituents,– list them in alphabetical order– number from the end of the chain that gives

the substituent encountered first the lower number

3-Ethyl-5-methylheptane

12

34

5 67 7

65

43 2

1

(not 3-methyl-5-ethylheptane)

Nomenclature - IUPAC

7. The prefixes di-, tri-, tetra-, etc. are not included in alphabetization

– alphabetize the names of substituents first and then insert these prefixes

4-Ethyl-2,2-dimethylhexane(not 2,2-dimethyl-4-ethylhexane)

12 3

45

6

Nomenclature - IUPAC

• Alkyl groups

1-methylethyl (isopropyl)

propyl

ethyl

methyl

CondensedStructural FormulaName

CH3

-CH2CH3

-CH3

-CH2CH2CH3

-CHCH3

1,1-dimethylethyl (tert-butyl)

1-methylpropyl (sec-butyl)

2-methylpropyl (isobutyl)

butyl

CH3

CH3

CH3

CH3

-CH2CH2CH2CH3

-CH2CHCH3

-CHCH2CH3

-CCH3

CondensedStructural FormulaName

Nomenclature - Common• The number of carbons in the alkane determines the

name– all alkanes with four carbons are butanes, those with

five carbons are pentanes, etc.

– iso- indicates the chain terminates in -CH(CH3)2; neo- that it terminates in -C(CH3)3

CH3CH2CH2CH2CH3

CH3CHCH3

CH3

CH3CH2CHCH3

CH3

CH3CH2CH2CH3

CH3CCH3

CH3

CH3

Pentane Isopentane

IsobutaneButane

Neopentane

Propyl Groups

C

H

H

H

C

H

H

C

H

H

H

n-propyl

C

H

H

H

C

H

C

H

H

H

isopropyl

H

A primary carbon A secondary carbon

=>

Butyl Groups

C

H

H

H

C

H

C

H

H

C

H

H

H

C

H

H

H

C

H

C

H

HH

C

H

H

n-butyl sec-butyl

H

H

A primary carbon A secondary carbon

=>

Isobutyl Groups

CH

H

H

C

CH H

C

HH

H H

CH

H

H

C

CH H

C H

HH

H

H

H

A primary carbon A tertiary carbon

=>

isobutyl tert-butyl

Alkyl Groups

Branches on carbon chains H

H C CH3 methyl H H H

H C C CH3CH2 ethyl H H

Branched Alkanes

CH3

CH3CHCH3

methyl groups

CH3 CH3

CH3CHCH2CHCH3

Naming Branched Alkanes

CH3 methyl branch

CH3CH2CH2CHCH2CH3

6 5 4 3 2 1 Count

Naming Branched Alkanes

CH3 methyl branch

CH3CH2CH2CHCH2CH3

6 5 4 3 2 1 Count

3-Methylhexane

on third C CH3 six carbon chain group

Naming Summary

1. Count the C’s in the longest chain

2. Name each attached group

3 Count the longest carbon chain to

give the first attached group the

smallest number

4. Name and locate each group

Dæmi

A. CH3 CH3

CH3CHCH2CHCH3

B. CH3 CH3

CH3CH2CHCH2CCH2CH3

CH3

Svör

A. CH3 CH3

CH3CHCH2CHCH3 2,4-dimethylpentane

B. CH3 CH3

CH3CH2CHCH2CCH2CH3

CH3 3,3,5-trimethylheptane

Dæmi

Write a condensed structure for

A. 3,4-dimethylheptane

B. 2,2-dimethyloctane

Solution Alk5

A. 3,4-dimethylheptane CH3

CH3CH2CHCHCH2CH2CH3

CH3

B. 2,2-dimethyloctane CH3

CH3CCH2CH2CH2CH2CH2CH3

CH3

Constitutional/structural Isomerism

• Byggingaisomerur:Byggingaisomerur: Efni með sömu mólikúlformúlu en ólíka byggingaformúlu t.d.: C4H10

CH3CH2CH2CH3

Butane(bp -0.5°C)

CH3

CH3CHCH3

2-Methylpropane(bp -11.6°C)

Byggingaisomerur 11.6

– Eru þetta byggingaisomerur?

– Finndu lengstu keðjuna– Númerið að fyrsta hliðarhóp – Berið saman lengd og greinar

CH3CHCH2CHCH3 CH3

CH3

CH3CH2CHCHCH3

CH3

CH3

and (each is C7H16)

CH3CH2CHCHCH3

CH3

CH3

CH3CHCH2CHCH3

CH3

CH3

4

454

31and

5

1 12 23

3

52

5 4 3

2 1

Constitutional Isomerism

World populationWorld populationis aboutis about6,000,000,0006,000,000,000

4,111,846,763

4,347

75

31

Constitutional Isomers

MolecularFormula

CH4

C5H12

C10H22

C15H32

C30H62

36,797,588C25H52

Learning Check Alk6

Write 3 isomers of C5H12 and name each.

Solution Alk6

CH3CH2CH2CH2CH3 pentane

CH3

CH3CHCH2CH3 2-methylbutane

CH3

CH3CCH3 2,2-dimethylpropane

CH3

Dæmi

Write a condensed structure for

A. 3,4-dimethylheptane

B. 2,2-dimethyloctane

Svör

A. 3,4-dimethylheptane CH3

CH3CH2CHCHCH2CH2CH3

CH3

B. 2,2-dimethyloctane CH3

CH3CCH2CH2CH2CH2CH2CH3

CH3

Dæmi

Write 3 isomers of C5H12 and name each.

Svör

CH3CH2CH2CH2CH3 pentane

CH3

CH3CHCH2CH3 2-methylbutane

CH3

CH3CCH3 2,2-dimethylpropane

CH3

Cycloalkanes

• Hringmyndanir (CH2 groups)

• Formula: CnH2n

• Óskautaðir og óleysanlegir í vatni eins og alkanar

• Bræðslu, suðumörk og flestir eiginleikar svipaðir og hjá samsvarandi alkönum =>

Nafnakerfi• Sykloalkanar eru venjulega orðstofninn• Hringur á hvorki upphaf né endi – en sé

hliðarhópur þarf að númera….• Raða í stafrófsröð.• Stöku sinnum finnast cyklo sem

hliðarhópar eins og syklopentyl.

CH2CH3

CH2CH3

CH3=>

Cycloalkanes

• Hringir með 5 og 6 C algengastir

• Structure and nomenclature– if two substituents, number from the

substituent of lower alphabetical order– if three or more substituents, number to give

them the lowest set of numbers and then list substituents in alphabetical order

Cycloalkanes

• Teiknaðir– Lína er C-C bond– Horn og lína þýðir C

C

C CC

CC

C

C H2C

H2C CH2

CH

CH2

CH

CH3

CH3

C8H16

Cycloalkanes

• Example:Example: name these cycloalkanes

(a) (b)

(c) (d)

Bicycloalkanes

• Bicycloalkane:Bicycloalkane: an alkane that contains two rings that share two carbons

Bicyclo[4.4.0]decane(Decalin)

Bicyclo[4.3.0]nonane(Hydrindane)

Bicyclo[2.2.1]heptane(Norbornane)

Bicycloalkanes

• Nomenclature– parent is the alkane of the same number of carbons as are in the

rings– number from a bridgehead, along longest bridge back to the

bridgehead, then along the next longest bridge, etc.– show the lengths of bridges in brackets, from longest to shortest

Bicyclo[2.2.1]heptane

1

2

3

4

5

67

Chair Conformer

=>

Boat Conformer

=>

Conformational Energy

=>

Axial and Equatorial Positions

=>

Monosubstituted Cyclohexanes

=>

1,3-Diaxial Interactions

=>

Disubstituted Cyclohexanes

=>

Cycloalkanes

Cyclopropane CH2

CH2 CH2

CyclobutaneCH2 CH2

CH2 CH2

More Cycloalkanes

Cyclopentane CH2

CH2 CH2

CH2 CH2

Cyclohexane

CH2

CH2 CH2

CH2 CH2

CH2

Naming Cycloalkanes with Side Groups

Number of Naming

side groups

One Side group name goes in front of the cycloalkane name.

Two Number the ring in the direction that gives the lowest numbers to the side groups.

Cycloalkanes with Side Groups

CH3

CH3

CH3

CH3

CH3

CH3

methylcyclopentane

1,2-dimethylcyclopentane

1,2,4-trimethylcyclohexane

DæmiCH3

CH3

CH3

CH3

CH3

Lausn

1,3-dimethylcyclohexane

methylcyclopentane

1,2-dimethylcyclobutane

CH3

CH3

CH3

CH3

CH3

Chapter 11.8 Alkenes and Alkynes

Alkenes and Alkynes

Geometric Isomers / rúmísomerur Alkena

Alken hefur C=C tvítengi

Alkýn hefur CC

Mettuð/Saturated og ómettuð/Unsaturated

Mettuð kolvetni hafa mesta mögulega fjölda vetnisatóma. CnH2n+2 fyrir alkan

Ómettuð kolvetni hafa færri vetnisatóm en mettuð

Ómettuð kolvetni hafa tví eða þrítengi milli C atóma

Milli tví og þrítengja er enginn snúningur

ALKEN

C=C tvítengi Endar á EN

H2C=CH2 ethen (ethylen)

H2C=CH-CH3 propen (propylen)

cyclohexen

Alkyn

Carbon-carbon triple bonds Endar á -yn

HCCH ethyn (acetylen)

HCC-CH3 propyn

Alken mun algengari en alkyn

Nafnakerfi alken/alkyn

Þegar keðja hefur 4 eða fleiri C, þá númera keðju þaðan sem styst er í tvítengi án tillits til alkýl hliðarhópa.

1 2 3 4

CH2=CHCH2CH3 1-buten eða But-1-en

CH3CH=CHCH3 2-buten eða But-2-en

CH3CHCHCH3 2-butyn eða But-2-yn

Dæmi

Ritið nöfn þessara efna:

A. CH3CH2CCCH3

CH3

B. CH3C=CHCH3 C.

CH3

Lausn

IUPAC nöfnin eru:

A. CH3CH2CH=CHCH3 2-pentyne

CH3

B. CH3C=CHCH3 C.

3-methyl-2-butene 3-methylcyclopentene

CH3

• Þar sem engin snúningur er um tvítengi geta myndast rúmísomerur (geometric isomers)

• Rúmisomerur geta myndast ef keðja er 4C eða lengri. Rúmisomerur myndast á C no. 2 eða ofar

• Sömu megin úr tvítengi er CIS

• Sitthvoru megin úr tvítengi er Trans

Cis and Trans Isomers

Efnið er 2-buten Cis/trans eru mögulegar

CH3 CH3 CH3

CH = CH CH = CH

cis trans CH3

Cis/trans

• Cis/trans isomerur hafa mikil áhrif á lögun sameinda

• Náttúran notar oftast Cis í lífverum og allar fitusýrur í náttúrunni eru Cis

• Cis og trans hafa líka ólík bræðslu og suðumörk

Trans fitusýrur - ómettaðar

Sömu ómettuðu – CIS

12.8 Alkenar och Alkynar

• π orkumeira, • Léttara brjóta - hvargjarnara Stöðugra, orkulægra• óhvarfgjarnt

Nafnareglur

• Liknar det för alkaner –en -yn• 1. Namnge den kolkedja som innehåller längsta kedja

med dubbel trippel bindning• 2. Numrera kedjan från den ände som ger dubbel trippel

bindning lägst siffra.

3. Placera siffra och namnet på substituenter framför alken-alkyn namn

•2-etyl-1-buten

• Cykloalkanar, þar er talið yfir tvíbinding til hliðarhóps

• Hefur efnið tvo tvíbindinga kallast það DÍEN

• Hexatrien

Butadien

Cis-trans isomer

• stereoisomeri,cis-trans• Almennt er trans stöðugra

Cis-trans isomer

• Cis och trans isomeri kräver att de grupper som binder till kolet är OLIKA

11.9 Aromatic Compounds

Aromatic compounds innihalda benzene. Benzene C6H6 has 6 C atoms and 6 H Atoms

Two possible ring structures show benzene.

HH

H

H

H

H

H

H

H

H

H

H

Benzene Structure

The structures for benzene are also written as one formula with a circle within the ring to represented the alternating double bonds.

Benzene

structure

Aromatic Compounds in Nature and Health

Many aromatic compounds are common in nature and in medicine.

Ibuprofen

CHCOOH

CH3

CH3CHCH2

CH3

Aspirin Vanillin

CHO

OCH3

OH

COOH

COOCH3

Naming Aromatic Compounds

Aromatar hafa Bensen sem orðstofn og hliðarhópar settir fyrir fram. (stundum!!!!).

methylbenzene chlorobenzene

ClCH3

Þegar bensen er tvískipt

(tveir hliðarhópar) er hringur númeraður þannig að hóparnir fái sem lægst númer.

Forskeytin ortho (1,2), meta (1,3-) and para (1,4-) eru einnig notuð.

(para-chloromethylbenzene)(meta-dichlorobenzene)(ortho-dimethylbenzene)

1,2-dimethylbenzene 1,3-dichlorobenzene 1-chloro-4-methylbenzene

Cl

CH3

Cl

Cl

CH3

CH3

Aromatar hafa verslunarnöfn

(common name). Ef tvískipt, þá oft með

ortho-, meta-, para-.

(Methylbenzene) (meta-chloromethylbenzene) (hydroxybenzene) Toluene meta-chlorotoluene phenol

OH

Cl

CH3CH3

Dæmi

Select the names for each structure:

1. Chlorocyclohexane2. Chlorobenzene3. 1-chlorobenzene

1. Meta-methyltoluene2. Meta-dimethylbenzene3. 1,3-dimethylbenzene

CH3

CH3

Cl

Svör

Select the names for each structure:

2. Chlorobenzene

1. Meta-methyltoluene

2. Meta-dimethylbenzene

3. 1,3-dimethylbenzene

CH3

CH3

Cl

Dæmi

Ritið byggingaformúlur:

A. 1,3-dichlorobenzene

B. Ortho-chlorotoluene

Svör

Byggingaformúlurnar:

A. 1,3-dichlorobenzene

B. Ortho-chlorotoluene

Cl

Cl

CH3

Cl

Learning Check Alk11

Identify the organic family for each:

CH3CH2CH3

B.

C.

A.

Solution Alk11

Identify the organic family for each:

alkane

cycloalkane

aromatic

CH3CH2CH3

B.

C.

A.

Fused Benzene Rings

Naphthalene

3,4-Benzpyrene

Carcinogens

• Fused ring of benzene cause cancer• Contain four or more fused rings• Present in tobacco smoke, auto exhaust, and

burned food• The more a person smokes, the greater the

risk of developing cancer

Unsaturated Fatty Acids

Fatty acids in vegetable oils are omega-6 acids (the first double bond occurs at carbon 6 counting from the methyl group)

A common omega-6 acid is linoleic acid

CH3CH2CH2CH2CH2CH=CHCH2CH=CH(CH2)7COOH

6

linoleic acid, a fatty acid

Trans Fats

In vegetable oils, the unsaturated fats usually contain cis double bonds.

During hydrogenation, some cis double bonds are converted to trans double bonds (more stable) causing a change in the fatty acid structure

If a label states “partially” or “fully hydrogenated”, the fats contain trans fatty acids.

Trans Fats

In the US, it is estimated that 2-4% of our total Calories is in the form of trans fatty acid.

trans fatty acids behave like saturated fatty acids in the body.

Several studies reported that trans fatty acids raise LDL-cholesterol. Some studies also report that trans fatty acid lower HDL-cholesterol

The trans fatty acids controversy will continue to be debated.

Fats and AtheroschlerosisInuit people of Alaska have a high fat diet

and high blood cholesterol levels, but a very

low occurrence of atherosclerosis and heart

attacks.

Fat in the Intuit diet was primarily from fish

such as salmon, tuna and herring rather than

from land animals (as in the American diet).

Omega-3 Fatty Acids

Fatty acids in the fish oils are mostly the omega-3 type (first double bond occurs at the third carbon counting from the methyl group).

linolenic acid 18 carbon atoms

CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH

eicosapentaenoic acid (EPA) 20 carbon atoms

CH3CH2(CH=CHCH2)5(CH2)2COOH

Atherosclerosis

Plaques of cholesterol adhere to the walls of the

blood vessels

Blood pressure rises as blood squeezes through

smaller blood vessels

Blood clots may form

Omega-3 fatty acids decrease the “sticking” of

blood platelets (fewer blood clots)

Omega-3 fatty acids can increase bleeding time

Learning Check HA6

(1) Ture or (2) False

A. ____ There are more unsaturated fats in vegetable oils.

B. ____ Vegetable oils have more omega-3 oils than found in fish.

C. ____ Hydrogenation of oils converts some cis-double bonds to trans- double bonds.

D. ____ Animal fats have more saturated fats.

Solution HA6

(1) True or (2) False

A. _T__ There are more unsaturated fats in vegetable oils.

B. _F__ Vegetable oils have more omega-3 oils than found in fish.

C. _T__ Hydrogenation of oils converts some cis-double bonds to trans- double bonds.

D. _T__ Animal fats have more saturated fats.