the double or triple bond. If the multiple bond is CH 3 C CCHCCH 3

Alkenes, Alkynes, and Aromatic Alkenes, Alkynes, and Aromatic

Compounds

Compounds Alkenes and Alkynes Alkenes and Alkynes

„

„ UnsaturatedUnsaturated

„

„ containcontain carboncarbon--carboncarbon doubledouble andand tripletriple bondbond toto which

which moremore hydrogenhydrogen atomsatoms cancan bebe addedadded..

„

„ AlkenesAlkenes:: carboncarbon--carboncarbon doubledouble bondsbonds

„

„ AlkynesAlkynes:: carboncarbon--carboncarbon tripletriple bondsbonds..

Naming Alkenes and Alkynes Naming Alkenes and Alkynes

„

„

IUPAC IUPAC nomenclature nomenclature rules rules for for alkenes alkenes and

and alkynes alkynes are are similar similar to to alkanes alkanes..

„

„

Step Step 1 p p 1.. Name Name the the parent parent compound pp compound.. pp Find

Find the the longest longest chain chain containing containing the the double

double or or triple triple bond bond,, and and name name the the parent

parent compound compound by by adding adding the the suffix suffix –

–ene ene or or – –yne yne to to the the name name of of the the main main chain

chain..

„

„StepStep 22:: NumberNumber thethe carboncarbon atomsatoms inin thethe parent

parent chain,chain, beginningbeginning atat thethe endend nearestnearest toto the

the doubledouble oror tripletriple bondbond.. IfIf thethe multiplemultiple bondbond isis an

an equalequal distancedistance fromfrom bothboth ends,ends, beginbegin numbering

numbering atat thethe endend nearernearer thethe firstfirst branchbranch point

point.. TheThe numbernumber indicatesindicates whichwhich carboncarbon thethe multiple

multiple bondbond isis AFTERAFTER (i(i ee betweenbetween 22 andand 33 isis multiple

multiple bondbond isis AFTERAFTER.. (i(i..ee.. betweenbetween 22 andand 33 isis 22--))

„

„StepStep 33:: AssignAssign numbersnumbers andand namesnames toto thethe branching

branching substituents,substituents, andand listlist thethe substituentssubstituents alphabetically

alphabetically.. UseUse commascommas toto separateseparate numbers,

numbers, andand hyphenshyphens toto separateseparate wordswords fromfrom numbers

numbers..

„

„StepStep 44.. Indicate

Indicate the the position position of of the the multiple

multiple--bond bond carbon carbon.. If If more more than than one one multiple

multiple bond bond is is present, present, identify identify the the position

position of of each each multiple multiple bond bond and and use use the

the appropriate appropriate ending ending diene diene,, triene triene,, tetraene

tetraene,, and and so so forth forth..

„

„StepStep 55 Assemble

Assemble the the name name

„

„StepStep 55.. Assemble

Assemble the the name name..

Naming Alkenes and Alkynes Naming Alkenes and Alkynes

When the carbon chain has 4 or more C atoms, When the carbon chain has 4 or more C atoms, number the chain to give the lowest number to number the chain to give the lowest number to the double or triple bond.

the double or triple bond.

1 2 3 4

1 2 3 4

1 2 3 4 1 2 3 4 CH

CH₂₂=CHCH=CHCH₂₂CHCH₃₃ 11--butenebutene butbut--11--eneene CH

CH₃₃CH=CHCHCH=CHCH₃₃ 22--butenebutene butbut--22--eneene CH

CH₃₃CC

≡≡

Assigning Priority Assigning Priority

„

„ Alkenes and alkynes are considered to have Alkenes and alkynes are considered to have equal priority

equal priority

„

„ In a molecule with In a molecule with bothboth a double and a triple a double and a triple bond whichever is closer to the end of the chain bond whichever is closer to the end of the chain bond, whichever is closer to the end of the chain bond, whichever is closer to the end of the chain determines the direction of numbering.

determines the direction of numbering.

„

„ In the case where each would have the same In the case where each would have the same position number, the double bond takes the position number, the double bond takes the lower number.

lower number.

„

„ In the name, “ene” comes before “yne” because In the name, “ene” comes before “yne” because of alphabetization.

of alphabetization.

Learning Check Learning Check

Write the IUPAC name for each of the Write the IUPAC name for each of the following unsaturated compounds:

following unsaturated compounds:

A

A CHCH CHCH CC

≡≡

A.

A. CHCH₃₃CHCH₂₂CC

≡≡

CH CH33

B.

B. CHCH₃₃C=CHCHC=CHCH₃₃ C. C.

CH₃

Multiple Double/Triple Bonds

Multiple Double/Triple Bonds ^Cis Cis--Trans Isomerism Trans Isomerism

„

„

Methane Methane is is tetrahedral, tetrahedral, ethylene ethylene is is planar, planar, and

and acetylene acetylene is is linear linear as as predicted predicted by by the the VSEPR

VSEPR theory theory discussed yy discussed earlier earlier..

Cis and Trans Isomers Cis and Trans Isomers

 Double bond is fixedDouble bond is fixed

 Cis/trans Isomers are possibleCis/trans Isomers are possible CH

CH₃₃ CHCH₃₃ CHCH₃₃ CH = CH

CH = CH CH = CHCH = CH cis

cis transtrans CHCH₃₃

„

„

The The two two carbons carbons and and the the four four atoms atoms that that make

make up up the the double double bond bond in in alkenes alkenes lie lie in in aa plane

plane.. Unlike Unlike carbon carbon--carbon carbon single single bonds, bonds, rotation

rotation around around carbon carbon--carbon carbon double double bond bond is

is not not possible possible.. As As aa result, result, aa new new kind kind of of isomerism

isomerism is is possible possible for for alkenes alkenes.. Because Because rotation

rotation is is not not possible possible around around carbon carbon-- carbon

carbon double double bonds, bonds, there there are are two two different

different kinds kinds of of 22--butenes butenes.. These These are are known

known as as cis cis--trans trans isomers isomers..

„

„

In In cis cis isomers, isomers, two two methyl methyl groups groups are are close

close together together on on the the same same side side of of the the double

double bond bond..

„

„ InIn transtrans isomer,isomer, twotwo methylmethyl groupsgroups areare farfar apart

apart onon oppositeopposite sideside ofof thethe doubledouble bondbond..

„

„ BothBoth ciscis andand transtrans isomersisomers havehave thethe samesame formula

formula andand connectionsconnections betweenbetween thethe atomsatoms but

but havehave differentdifferent threethree dimensionaldimensional structuresstructures because

because thethe wayway thethe groupsgroups areare attachedattached toto thethe carbons

carbons..

„

„ CisCis--transtrans isomerismisomerism occursoccurs inin anan alkenealkene whenever

whenever eacheach doubledouble bondbond carboncarbon isis bondedbonded to

to twotwo differentdifferent substituentsubstituent groupsgroups.. CisCis--transtrans isomerism

isomerism isis notnot possiblepossible ifif oneone ofof thethe doubledouble bond

bond carbonscarbons isis attachedattached toto twotwo identicalidentical groups

groups..

Unsaturated Fatty Acids Unsaturated Fatty Acids

z

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

counting from the methyl group)

z

z A common omegaA common omega--6 acid is linoleic acid6 acid is linoleic acid

CH

CH₃₃CHCH₂₂CHCH₂₂CHCH₂₂CHCH₂₂CH=CHCHCH=CHCH₂₂CH=CH(CHCH=CH(CH₂₂))₇₇COOHCOOH 6

6

linoleic acid, a fatty acid linoleic acid, a fatty acid

Trans Trans Fats Fats

‹

‹In vegetable oils, the unsaturated fats In vegetable oils, the unsaturated fats usually contain

usually contain ciscisdouble bonds. double bonds.

‹

‹During hydrogenation, some During hydrogenation, some cis cis double double bonds are converted to

bonds are converted totranstransdouble bondsdouble bonds bonds are converted to

bonds are converted to trans trans double bonds double bonds (more stable) causing a change in the fatty (more stable) causing a change in the fatty acid structure

acid structure

‹

‹If a label states “partially” or “fully If a label states “partially” or “fully hydrogenated”, the fats contain

hydrogenated”, the fats contain transtransfatty fatty acids.

acids.

Trans Trans Fats Fats

‹

‹In the US, it is estimated that 2In the US, it is estimated that 2--4% of our 4% of our total Calories is in the form of

total Calories is in the form of transtransfatty fatty acid.

acid.

‹

‹transtransfatty acids behave like saturated fattyfatty acids behave like saturated fatty

‹

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

acids in the body.

‹

‹Several studies reported that trans fatty Several studies reported that trans fatty acids raise LDL

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

cholesterol

‹

‹The trans fatty acids controversy will The trans fatty acids controversy will

Fats and Atheroschlerosis Fats and Atheroschlerosis

z

z Inuit people of Alaska have a high fat diet Inuit people of Alaska have a high fat diet and high blood cholesterol levels, but a and high blood cholesterol levels, but a very low occurrence of atherosclerosis and very low occurrence of atherosclerosis and very low occurrence of atherosclerosis and very low occurrence of atherosclerosis and heart attacks.

heart attacks.

z

z Fat in the Intuit diet was primarily from Fat in the Intuit diet was primarily from fish such as salmon, tuna and herring fish such as salmon, tuna and herring rather than from land animals (as in the rather than from land animals (as in the American diet).

American diet).

Omega

Omega--3 Fatty Acids 3 Fatty Acids

z

z Fatty acids in the fish oils are mostly the Fatty acids in the fish oils are mostly the omega

omega--3 type (first double bond occurs at the 3 type (first double bond occurs at the third carbon counting from the methyl group).

third carbon counting from the methyl group).

z

z linolenic acid 18 carbon atoms linolenic acid 18 carbon atoms CH

CH₃₃CHCH₂₂CH=CHCHCH=CHCH₂₂CH=CHCHCH=CHCH₂₂CH=CH(CHCH=CH(CH₂₂))₇₇COOHCOOH

↑↑

z

z eicosapentaenoic acid (EPA)eicosapentaenoic acid (EPA) 20 carbon atoms 20 carbon atoms CH

CH₃₃CHCH₂₂(CH=CHCH(CH=CHCH₂₂))₅₅(CH(CH₂₂))₂₂COOH COOH

Atherosclerosis Atherosclerosis

z

z Plaques of cholesterol adhere to the walls of Plaques of cholesterol adhere to the walls of the blood vessels

the blood vessels

z

z Blood pressure rises as blood squeezes through Blood pressure rises as blood squeezes through smaller blood vessels

smaller blood vessels

z

z Blood clots may formBlood clots may form

z

z OmegaOmega--3 fatty acids decrease the “sticking” of 3 fatty acids decrease the “sticking” of blood platelets (fewer blood clots)

blood platelets (fewer blood clots)

z

z OmegaOmega--3 fatty acids can increase bleeding time3 fatty acids can increase bleeding time

Name These Name These

C C CH₃ H

CH₃ CH₂CH₃

C C Cl

H

CH₂ Cl

CH₃

Aromatic Compounds and Aromatic Compounds and

Benzene Benzene

Aromatic compounds contain benzene.

Aromatic compounds contain benzene.

Benzene, C

Benzene, C₆₆HH_{6 6} , is represented as a six carbon , is represented as a six carbon ring with 3 double bonds.

ring with 3 double bonds.gg

Two possible can be drawn to show benzene in Two possible can be drawn to show benzene in this form.

this form. H

H

H H H H H

H

H H H H

Aromatic Compounds Aromatic Compounds and the Structure of Benzene and the Structure of Benzene

„

„

In In the the early early days days the the word word aromatics aromatics was was used

used to to described described many many fragrant fragrant molecules

molecules isolated isolated from from natural natural sources sources..

Today

Today the the term term aromatic aromatic is is used used to to describe

describe benzene benzene like like molecules molecules..

„

„

Benzene Benzene is is aa flat, flat, symmetrical symmetrical molecule molecule with

with the the molecular molecular formula formula CC

H H

..

„

„

It It has has alternating alternating three three carbon carbon--carbon carbon double

double and and three three single single bonds bonds..

„

„

Benzene’s Benzene’s relatively relatively lack lack of of chemical chemical reactivity

reactivity is is due due to to its its structure structure..

„

„

There There are are two two possible possible structures structures with with alternating

alternating double double and and single single bonds bonds..

„

„ ExperimentalExperimental evidenceevidence suggestsuggest thatthat allall sixsix carbon

carbon--carboncarbon bondsbonds inin benzenebenzene areare identicalidentical..

„

„ TheThe properties,properties, includingincluding thethe aboveabove one,one, ofof benzene

benzene cancan onlyonly bebe explainedexplained byby assumingassuming that

that thethe actualactual structurestructure ofof benzenebenzene isis anan average

average ofof thethe aboveabove twotwo possiblepossible equivalentequivalent structures

structures--knownknown asasresonanceresonance..

„

„ SimpleSimple aromaticaromatic compoundscompounds likelike benzenebenzene areare non

non--polar,polar, insolubleinsoluble inin water,water, volatile,volatile, andand flammable

flammable..

„

„ UnlikeUnlike alkenes,alkenes, severalseveral aromaticaromatic hydrocarbonshydrocarbons are

are toxictoxic.. BenzeneBenzene itselfitself isis implicatedimplicated asas aa cancer

cancer causingcausing chemicalchemical..

Aromatic Compounds in Nature Aromatic Compounds in Nature

and Health and Health

Many aromatic compounds are common in nature Many aromatic compounds are common in nature and in medicine.

and in medicine.

COOH CHO

COOH COOCH3

OCH3 OH Aspirin Vanillin

CHCOOH CH3 CH3CHCH2

CH3

Ibuprofen

Naming Aromatic Compounds Naming Aromatic Compounds

Aromatic compounds are named with

Aromatic compounds are named with benzene as the benzene as the parent chain.

parent chain. One side group is named in front of the One side group is named in front of the name

name benzene.benzene.

-- No number is needed for monoNo number is needed for mono--substituted benzene substituted benzene since all the ring positions are identical

since all the ring positions are identical since all the ring positions are identical.

since all the ring positions are identical.

methylbenzene

methylbenzene chlorobenzenechlorobenzene (toluene)

(toluene)

CH₃ Cl

Naming Aromatic Compounds Naming Aromatic Compounds

When two groups are attached to benzene, the When two groups are attached to benzene, the ring is numbered to give the lower numbers to the ring is numbered to give the lower numbers to the side groups. The prefixes

side groups. The prefixes ortho (1,2), meta (1,3ortho (1,2), meta (1,3--) ) and

andpara (1,4para (1,4--) pp ( ,( , ))) areare also used.also used.

CH3 CH3

Cl

Cl

Cl

CH3

1,2-dimethylbenzene 1,3-dichlorobenzene 1-chloro-4-methylbenzene (ortho-dimethylbenzene) (meta-dichlorobenzene) (para-chloromethylbenzene)

Some Common Names Some Common Names

Some substituted benzene rings also use a common Some substituted benzene rings also use a common name. Then naming with additional more side name. Then naming with additional more side groups uses the

groups uses the orthoortho--, meta, meta--, para, para--system.system.

CH3

Cl

CH3 OH

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

„

„ ManyMany substitutedsubstituted aromaticaromatic compoundscompounds havehave common

common namesnames inin additionaddition toto theirtheir systematic

systematic namesnames..

Learning Check Learning Check

Select the names for each structure:

Select the names for each structure:

a. Chlorocyclohexane a. Chlorocyclohexane Cl

b. Chlorobenzene b. Chlorobenzene c. 1

c. 1--chlorobenzenechlorobenzene a. a. MetaMeta--xylenexylene

b. b. MetaMeta--dimethylbenzenedimethylbenzene c. 1,3

c. 1,3--dimethylbenzenedimethylbenzene CH3

CH3

Learning Check Learning Check

Write the structural formulas for each of the Write the structural formulas for each of the following:

following:

A. 1,3

A. 1,3--dichlorobenzene,, dichlorobenzene

B.

B. OrthoOrtho--chlorotoluenechlorotoluene

New Attached Groups New Attached Groups

„

„

Phenyl Phenyl

„

„

Benzyl Benzyl

4-phenyl-1-butene

yy

„

„

Nitro Nitro --NO NO

2,4,6

2,4,6--trinitrotoluenetrinitrotoluene Benzyl alcohol

Refer to your chart for order of priority!

PCBs PCBs

(Polychlorinated Biphenyls) (Polychlorinated Biphenyls)

„

„ There are 209 There are 209 varieties of PCBs, varieties of PCBs, known individually known individually as congeners A as congeners A as congeners. A as congeners. A congener may have congener may have between 1 and 10 between 1 and 10 chlorine atoms, chlorine atoms, which may be which may be located at various located at various positions on the PCB positions on the PCB molecule.

molecule.

PCBs PCBs

„

„ PCBs are mixtures of manPCBs are mixtures of man--made made chemicals with similar chemical chemicals with similar chemical structures. PCBs can range from oily structures. PCBs can range from oily liquids to waxy solids. Due to their liquids to waxy solids. Due to their non

non--flammability, chemical stability, flammability, chemical stability, high boiling point and electrical high boiling point and electrical insulating properties, PCBs were used insulating properties, PCBs were used in hundreds of industrial and in hundreds of industrial and i l li ti i l di i l li ti i l di commercial applications including commercial applications including electrical, heat transfer, and hydraulic electrical, heat transfer, and hydraulic equipment; as plasticizers in paints, equipment; as plasticizers in paints, plastics and rubber products; in plastics and rubber products; in pigments, dyes and carbonless copy pigments, dyes and carbonless copy paper and many other applications.

paper and many other applications.

More than 1.5 billion pounds of PCBs More than 1.5 billion pounds of PCBs were manufactured in the United were manufactured in the United States prior to cessation of production States prior to cessation of production in 1977.

in 1977.