1 Announcements & Agenda (03/30/07) Quiz on Wednesday (Chirality & Ch 13) Will hand out HW practice...
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Transcript of 1 Announcements & Agenda (03/30/07) Quiz on Wednesday (Chirality & Ch 13) Will hand out HW practice...
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AnnouncementsAnnouncements & Agenda& Agenda (03/30/07)(03/30/07)
Quiz on Wednesday (Chirality & Ch 13)Quiz on Wednesday (Chirality & Ch 13)
Will hand out HW practice on MondayWill hand out HW practice on Monday
Schedule for rest of semester on M or WSchedule for rest of semester on M or W
<10 people at review on Wed <10 people at review on Wed Great place for help!Great place for help!
TodayToday Fisher projections (12.6)Fisher projections (12.6) Carboxylic acids (13.1, 13.2)Carboxylic acids (13.1, 13.2) Esters (13.3)Esters (13.3)
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Fischer Projections of Chiral Molecules Fischer Projections of Chiral Molecules (12.6)(12.6)
• are a 2-dimensional representation of a 3-D molecule.are a 2-dimensional representation of a 3-D molecule.
• places the most oxidized group at the top.places the most oxidized group at the top.
• uses vertical lines in place of dashes for bonds that uses vertical lines in place of dashes for bonds that go back.go back.
• uses horizontal lines in place of wedges for bonds uses horizontal lines in place of wedges for bonds that come forward.that come forward.
33
Drawing Fischer ProjectionsDrawing Fischer Projections
44
D and L NotationsD and L Notations• By convention, the letter L is assigned to the structure By convention, the letter L is assigned to the structure
with the with the —OH on the left.—OH on the left.• The letter D is assigned to the structure with the —OH on The letter D is assigned to the structure with the —OH on
the right.the right.• FYI: Other conventions exist too…FYI: Other conventions exist too…
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Learning CheckLearning CheckIndicate whether each pair is a mirror image Indicate whether each pair is a mirror image that cannot be superimposed (enantiomers).that cannot be superimposed (enantiomers).
YesYes
NoNoB.
A.
and
and
Br
CH3 H
CH2OH
C
H
CH3 H
Cl
C
Br
H CH3
CH2OH
C
H
H CH3
Cl
C
66
Carboxylic Acids (13.1) Carboxylic Acids (13.1)
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Ch 13 Practice ProblemsCh 13 Practice Problems
11 22 33 44 55
13.01, 13.07, 13.09, 13.11, 13.13, 13.01, 13.07, 13.09, 13.11, 13.13, 13.15, 13.17, 13.19, 13.21, 13.25, 13.15, 13.17, 13.19, 13.21, 13.25, 13.29, 13.31, 13.33, 13.37, 13.39, 13.29, 13.31, 13.33, 13.37, 13.39, 13.41, 13.43, 13.49, 13.55, 13.57, 13.41, 13.43, 13.49, 13.55, 13.57, 13.59, 13.63, 13.65, 13.67, 13.69, 13.59, 13.63, 13.65, 13.67, 13.69, 13.71, 13.73, 13.74, 13.75, 13.76 13.71, 13.73, 13.74, 13.75, 13.76
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A carboxylic acid contains a A carboxylic acid contains a carboxyl groupcarboxyl group, , whichwhich• is a carbonyl group (C=O) attached to a hydroxyl is a carbonyl group (C=O) attached to a hydroxyl
group (group (——OH).OH).
OO
CHCH3 3 —— CC——OHOH hydroxyl grouphydroxyl group
carbonyl groupcarbonyl group
Will also see a carboxylic acid written as CHWill also see a carboxylic acid written as CH33COCOOHOH
Carboxylic Acids Carboxylic Acids
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The IUPAC names of carboxylic acids: The IUPAC names of carboxylic acids:
• Replace the -Replace the -ee in the alkane name with - in the alkane name with -ooic acidic acid..
CHCH44 methan methanee HCOOH methan HCOOH methanoicoic acidacid
CHCH33——CHCH3 3 ethanethanee CH CH33——COOH ethanCOOH ethanoicoic acidacid
• Number substituents from the carboxyl carbon 1.Number substituents from the carboxyl carbon 1.
CHCH3 3 OO | | ║║
CHCH33——CHCH—CH—CH22—C—OH—C—OH 4 3 2 14 3 2 1
3-methylbutanoic acid3-methylbutanoic acid
Recognizing Carboxylic Acids from NamesRecognizing Carboxylic Acids from Names
Don’t need to Don’t need to know numbering know numbering rules!!!rules!!!
1010
Names & Sources of Some Carboxylic Acids Names & Sources of Some Carboxylic Acids (Know These)(Know These)
By the way, very common in nature:By the way, very common in nature:Citric acid, tartaric acid, lactic acid, fatty acids, etc.Citric acid, tartaric acid, lactic acid, fatty acids, etc.
1111
Polarity of Carboxylic Acids Polarity of Carboxylic Acids • strongly polar because they have two polar groups: strongly polar because they have two polar groups:
[hydroxyl ([hydroxyl (−−OH) and carbonyl (C=O)]OH) and carbonyl (C=O)]
• form form dimersdimers in which hydrogen bonds form between two in which hydrogen bonds form between two carboxyl groups.carboxyl groups.
O HO H—O—O |||| | |
CHCH33—C—C C—CH C—CH33
|| ||||
O—H O—H O O A dimer of acetic acidA dimer of acetic acid
• have higher boiling points than alcohols, ketones, and have higher boiling points than alcohols, ketones, and aldehydes of similar mass.aldehydes of similar mass.
…
…
1212
Comparison of Boiling PointsComparison of Boiling Points
CompoundCompound Molar Mass Boiling Point Molar Mass Boiling Point
OO
║║
CHCH33−CH−CH22−C−H−C−H 5858 49°C49°C
CHCH33−CH−CH22−CH−CH22−OH−OH 6060 97°C97°C
OO
║║
CHCH33−C−OH−C−OH 6060 118°C118°C
1313
Solubility in WaterSolubility in Water
Carboxylic acids: Carboxylic acids: • form hydrogen form hydrogen
bonds with many bonds with many water molecules.water molecules.
• with 1-4 carbon with 1-4 carbon atoms are very atoms are very soluble in water.soluble in water.
Water molecules
1414
Boiling Points and SolubilityBoiling Points and Solubility
1515
Acidity of Carboxylic AcidsAcidity of Carboxylic Acids
Carboxylic acids Carboxylic acids • are weak acids.are weak acids.• ionize in water to produce carboxylate ionize in water to produce carboxylate
ions and hydronium ions.ions and hydronium ions.
O O OO ║║ ║║
CHCH33−−CC−−OH + HOH + H22OO CH CH33−−CC−−OO– – + +
HH33OO++
~1%~1%
1616
Neutralization of Carboxylic AcidsNeutralization of Carboxylic Acids
Carboxylic acid saltsCarboxylic acid salts • are a product of the neutralization of a carboxylic acid are a product of the neutralization of a carboxylic acid
with a strong base. with a strong base.
CHCH33——COOH + NaOH CHCOOH + NaOH CH33——COOCOO– – NaNa+ + + H+ H22OO
acetic acidacetic acid sodium acetate sodium acetate
(carboxylic acid salt)(carboxylic acid salt)• are used as preservatives and flavor enhancers.are used as preservatives and flavor enhancers.
1717
Learning CheckLearning Check
Write the equation for the reaction of propanoic acid withWrite the equation for the reaction of propanoic acid with
A. water A. water
B. KOHB. KOH
CHCH33—CH—CH22—COOH + H—COOH + H22O CHO CH33—CH—CH22—COO—COO–– + H + H33OO++
CHCH33—CH—CH22—COOH + KOH CH—COOH + KOH CH33—CH—CH22—COO—COO–– K K++ + H + H22OO
1818
Esters (13.3)Esters (13.3)
1919
EstersEsters
In an In an esterester, the H in the carboxyl group is replaced, the H in the carboxyl group is replacedwith an alkyl group.with an alkyl group.
OO
CHCH3 3 —— CC—O—O —CH—CH33
ester groupester group
2020
EsterificationEsterification: reaction of a carboxylic acid & alcohol : reaction of a carboxylic acid & alcohol in the presence of an acid catalyst to produce an in the presence of an acid catalyst to produce an ester.ester.
OO HH++
CHCH33——CC——OHOH ++ HH——OO——CHCH22——CHCH3 3
OO
CHCH33——CC——OO——CHCH22——CHCH3 3 ++ HH22OO ethyl acetate (an ester)ethyl acetate (an ester)
EsterificationEsterification
FYI: The acid half of an ester is called an “acyl” groupFYI: The acid half of an ester is called an “acyl” group
Also called a condensation reaction!Also called a condensation reaction!
2121
Write the equation for the reaction of propanoic Write the equation for the reaction of propanoic acid and methanol in the presence of an acid acid and methanol in the presence of an acid catalyst. catalyst.
OO HH++
CHCH33——CHCH22——CC——OHOH + + HH——OO——CHCH33
propanoic acid methanolpropanoic acid methanol OO
CHCH33——CHCH22——CC——OO——CHCH3 3 + + HH22OO
Learning CheckLearning Check
2222
Ester ProductsEster Products
AspirinAspirin• is used to relieve pain and is used to relieve pain and
reduce inflammation.reduce inflammation.• is an ester of salicylic acid is an ester of salicylic acid
and acetic acid.and acetic acid.
Oil of wintergreenOil of wintergreen• is used to soothe sore is used to soothe sore
muscles. muscles. • is an ester of salicylic acid is an ester of salicylic acid
and methanol. and methanol.
CH3
O
CO
OH
O
C
OH
CH3O
O
C
2323
Naming EstersNaming Esters
The name of an ester contains the names ofThe name of an ester contains the names of
• the the alkyl groupalkyl group from the alcohol. from the alcohol.
• the carbon chain from the acid with the carbon chain from the acid with ––ateate ending. ending.
methylmethyl ethanoate (acetate)ethanoate (acetate)
OO
CHCH33—— OO——CC —CH—CH33
IUPAC: IUPAC: methylmethyl ethanoateethanoate
common:common: methylmethyl acetateacetate
-oate: means -oate: means ester presentester present
2424
Esters in PlantsEsters in Plants
Esters give flowers and fruits their Esters give flowers and fruits their pleasant fragrances and flavors.pleasant fragrances and flavors.
2525
• an ester reacts with water to produce a an ester reacts with water to produce a carboxylic acid and an alcohol.carboxylic acid and an alcohol.
• an acid catalyst is required. an acid catalyst is required. OO
HH++
HH——CC——OO——CHCH22——CHCH3 3 ++ HH22OO
OO HH——CC——OHOH + + HH——OO——CHCH22——CHCH33
Acid Acid HydrolysisHydrolysis of Esters of Esters
2626
• is the reaction of an ester with a strong base. is the reaction of an ester with a strong base.
• produces the salt of the carboxylic acid and an produces the salt of the carboxylic acid and an alcohol.alcohol. OO
|||| CHCH33——CC—O—O——CHCH22——CHCH3 3 ++ NaOHNaOH
OO CHCH33——CC——OO– – NaNa++ + + HHOO——CHCH22——CHCH33
salt of carboxylic acid alcoholsalt of carboxylic acid alcohol
Base Base HydrolysisHydrolysis (Saponification) (Saponification)
2727
Base Base HydrolysisHydrolysis of Fatty Acids of Fatty Acids Produces SoapsProduces Soaps
2828
Carboxylic acids with lots of carbons are fatty Carboxylic acids with lots of carbons are fatty acids (usually even #, 10, 12, 14, 16, 18)acids (usually even #, 10, 12, 14, 16, 18)
Sodium salts of fatty acids are soaps.
2929
Cleaning Action of SoapCleaning Action of Soap
A A soapsoap• contains a nonpolar end contains a nonpolar end
that dissolves in that dissolves in nonpolar fats and oils, nonpolar fats and oils, and a polar end that and a polar end that dissolves in water.dissolves in water.
• forms groups of soap forms groups of soap molecules called molecules called micellesmicelles that dissolve in that dissolve in water and are washed water and are washed away.away.
3030
Write the organic products when methyl acetate reacts withWrite the organic products when methyl acetate reacts withA. water and an acid catalyst.A. water and an acid catalyst.
OO CHCH33——CC——OH + HOH + HOO——CHCH33
B. KOH.B. KOH. OO
CHCH33——CC——OO– – KK++ + H + HOO——CHCH33
Learning CheckLearning Check