chapter_21.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Chapter 21,*,1,Chapter 21,2,Chapter 21,3,Chapter 21,4,Chapter 21,5,Chapter 21,Chapter 21Carboxylic Acid Derivatives,Organic Chemistry,5,th,EditionL.G.Wade,Jr.,Acid Derivatives,All can be converted to the carboxylic acid by acidic or basic hydrolysis.,Esters and amides common in nature.,=,7,Chapter 21,8,Chapter 21,Naming Esters,Esters are named as,alkyl,carboxylates,.,Alkyl,from the alcohol,carboxylate,from the carboxylic acid precursor.,isobutyl acetate,2-methylpropyl,ethanoatebenzyl,formate,benzyl,methanoate,=,9,Chapter 21,Cyclic Esters,Reaction of-OH and-COOH on same molecule produces a cyclic ester,lactone,.,To name,add word,lactone,to the IUPAC acid name or replace the-,ic,acid,of common name with-,olactone,.,4-hydroxy-2-methylpentanoic acid,lactone,-methyl-,valerolactone,=,10,Chapter 21,Amides,Product of the reaction of a carboxylic acid and ammonia or an amine.,Not basic because the lone pair on nitrogen is delocalized by resonance.,Bond angles around N,are close to 120,.=,11,Chapter 21,Classes of Amides,1,amide has one C-N bond(two N-H).,2 amide or,N,-substituted amide has two C-N bonds(one N-H).,3 amide or,N,N,-,disubstituted,amide has three C-N bonds(no N-H).=,12,Chapter 21,Naming Amides,For 1,amide,drop-,ic,or-,oic,acid,from the carboxylic acid name,add-,amide,.,For 2 and 3 amides,the alkyl groups bonded to nitrogen are named with,N,-to indicate their position.,N,-ethyl-,N,2-dimethylpropanamide,N,-ethyl-,N,-,methylisobutyramide,=,13,Chapter 21,Cyclic Amides,Reaction of-NH,2,and-COOH on same molecule produces a cyclic amide,lactam,.,To name,add word,lactam,to the IUPAC acid name or replace the-,ic,acid,of common name with-,olactam,.,4-aminopentanoic acid,lactam,-,valerolactam,=,14,Chapter 21,Nitriles,-C,N can be hydrolyzed to carboxylic acid,so,nitriles,are acid derivatives.,Nitrogen is,sp,hybridized,lone pair tightly held,so not very basic.(,p,K,b,about 24).,=,15,Chapter 21,Naming,Nitriles,For IUPAC names,add-,nitrile,to the alkane name.Common names come from the carboxylic acid.Replace-,ic,acid,with-,onitrile,.,5-bromohexanenitrile,-,bromocapronitrile,Cyclohexanecarbonitrile,=,16,Chapter 21,Acid Halides,More reactive than acids;the halogen withdraws e,-,density from carbonyl.,Named by replacing-,ic,acid,with-,yl,halide,.,benzoyl,chloride,3-bromobutanoyl bromide,-,bromobutyryl,bromide =,17,Chapter 21,Acid Anhydrides,Two molecules of acid combine with the loss of water to form the anhydride.,Anhydrides are more reactive than acids,but less reactive than acid chlorides.,A,carboxylate,ion is the leaving group in nucleophilic,acyl,substitution reactions.,=,18,Chapter 21,Naming Anhydrides,The word,acid,is replaced with,anhydride,.,For a mixed anhydride,name both acids.,Diacids,may form anhydrides if a 5-or 6-membered ring is the product.,ethanoic,anhydride,acetic anhydride,1,2-benzenedicarboxylic anhydride,phthalic,anhydride,=,19,Chapter 21,Multifunctional Compounds,The functional group with the highest priority determines the parent name.,Acid ester amide,nitrile,aldehyde ketone alcohol amine alkene alkyne.,ethyl,o,-cyanobenzoate,=,20,Chapter 21,Boiling Points,Even 3,amides have,strong attractions.,=,21,Chapter 21,Melting Points,Amides have very high melting points.,Melting points increase with increasing number of N-H bonds.,m.p.-61,C,m.p.28,C,m.p.79,C,=,22,Chapter 21,Solubility,Acid chlorides and anhydrides are too reactive to be used with water or alcohol.,Esters,3,amides,and,nitriles,are good polar,aprotic,solvents.,Solvents commonly used in organic reactions:,Ethyl acetate,Dimethylformamide,(DMF),Acetonitrile,=,23,Chapter 21,IR Spectroscopy,=,=,24,Chapter 21,1,H NMR Spectroscopy,=,25,Chapter 21,13,C NMR Spectroscopy,=,26,Chapter 21,Interconversion,ofAcid Derivatives,Nucleophile adds to the carbonyl to form a tetrahedral intermediate.,Leaving group leaves and C=O regenerates.,=,27,Chapter 21,Reactivity,Reactivity decreases as leaving group becomes more basic.,=,28,Chapter 21,Origins of Reactivity Trends,Inductive effects,Elements to the,right,in a row of PT are,more,electronegative(nuclear charge increase).,Elements,down,a column in PT are,less,electronegative(size),but bonds to them get weaker.,29,Chapter 21,Donating ability of L,decreases,from left to right in the periodic table.The,greater,the resonance,the,shorter,the C-L bond.,2.Resonance effects,At the extreme:,Hindered rotation,in amides on the NMR time scale.The nitrogen is,sp,2,-hybridized to maximize resonance.,Acetyl chloride,Acetamide,30,Chapter 21,Interconversion,of Derivatives,More reactive derivatives can be converted to less reactive derivatives.,=,31,Chapter 21,Acid Chloride to Anhydride,Acid,or,carboxylate,ion attacks the C=O.,Tetrahedral intermediate forms.,Chloride ion leaves,C=O is restored,H,+,is abstracted.=,32,Chapter 21,Acid Chloride to Ester,Alcohol attacks the C=O.,Tetrahedral intermediate forms.,Chloride ion leaves,C=O is restored,H,+,is abstracted.=,33,Chapter 21,Acid Chloride to Amide,Ammonia yields a 1,amide,A 1 amine yields a 2 amide,A 2 amine yields a 3 amide,=,34,Chapter 21,Anhydride to Ester,Alcohol attacks one C=O of anhydride.,Tetrahedral intermediate forms.,Carboxylate,ion leaves,C=O is restored,H,+,is abstracted.=,35,Chapter 21,Anhydride to Amide,Ammonia yields a 1,amide,A 1 amine yields a 2 amide,A 2 amine yields a 3 amide,=,36,Chapter 21,Ester to Amide,Nucleophile must be NH,3,or 1,amine.,Prolonged heating required.,Surprise!,=,37,Chapter 21,Leaving Groups,A strong base is not usually a leaving group unless its in an exothermic step.,=,38,Chapter 21,Transesterification,One,alkoxy,group can be replaced by another with acid or base catalyst.,Use large excess of preferred alcohol.,=,39,Chapter 21,Hydrolysis of Acid Chlorides and Anhydrides,Hydrolysis occurs quickly,even in moist air with no acid or base catalyst.,Reagents must be protected from moisture.,=,40,Chapter 21,Acid Hydrolysis of Esters,Reverse of Fischer,esterification,.,Reaches equilibrium.,Use a large excess of water.,=,41,Chapter 21,Saponification,Base-catalyzed hydrolysis of ester.,“,Saponification,”means“soap-making.”,Soaps are made by heating NaOH with a fat(,triester,of glycerol)to produce the sodium salt of a fatty acid-a soap.,One example of a soap is sodium,stearate,Na,+-,OOC(CH,2,),16,CH,3,.=,42,Chapter 21,Hydrolysis of Amides,Prolonged heating in 6 M HCl or 40%aqueous NaOH is required.,=,43,Chapter 21,Hydrolysis of,Nitriles,Under mild conditions,nitriles,hydrolyze to an amide.,Heating with aqueous acid or base will hydrolyze a,nitrile,to an acid.,=,44,Chapter 21,Reduction to Alcohols,Lithium aluminum hydride reduces acids,acid chlorides,and esters to primary alcohols.,=,45,Chapter 21,Reduction to Aldehydes,Acid chlorides will react with a weaker reducing agent to yield an aldehyde.,=46,Chapter 21,Reduction to Amines,Lithium aluminum hydride reduces amides and,nitriles,to amines.,Nitriles,and 1,amides reduce to 1 amines.,A 2 amide reduces to a 2 amine.,A 3 amide reduces to a 3 amine.,=,47,Chapter 21,Organometallic,Reagents,Grignard reagents and,organolithium,reagents add twice to acid chlorides and esters to give alcohols after,protonation,.,=,48,Chapter 21,Grignard Reagentsand,Nitriles,A Grignard reagent or,organolithium,reagent attacks the,cyano,group to yield an,imine,which is hydrolyzed to a ketone.,=,49,Chapter 21,50,Chapter 21,Acid Chloride Synthesis,Use,thionyl,chloride,SOCl,2,or,oxalyl,chloride,(COCl),2,.,Other products are gases.,=,51,Chapter 21,Acid Chloride Reactions(1),acid,ester,amide,acid anhydride,=,52,Chapter 21,Acid Chloride Reactions(2),3,alcohol,ketone,1,alcohol,aldehyde,acylbenzene,=,53,Chapter 21,Industrial Synthesis of Acetic Anhydride,Four billion pounds/year produced.,Use high heat(750,C)and,triethyl,phosphate catalyst to produce ketene.,=,乙烯酮,54,Chapter 21,Lab Synthesisof Anhydrides,React acid chloride with carboxylic acid or,carboxylate,ion.,Heat,dicarboxylic,acids to form cyclic anhydrides.,=,55,Chapter 21,Anhydride Reactions,acid,ester,amide,=,acylbenzene,56,Chapter 21,Anhydride vs.Acid Chloride,Acetic anhydride is cheaper,gives a better yield than acetyl chloride.,Use acetic formic anhydride to produce,formate,esters and,formamides,.,Use cyclic anhydrides to produce a,difunctional,molecule.,=,57,Chapter 21,Synthesis of Estersacid,acid chloride,acid anhydride,methyl ester,=,58,Chapter 21,Reactions of Esters,acid,ester,amide,1,alcohol,3,alcohol,=,59,Chapter 21,Lactones,Formation favored for five-and six-,membered,rings.,For larger rings,remove water to shift equilibrium toward products,=,60,Chapter 21,Synthesis of Amidesacid,acid anhydride,ester,nitrile,=,acid chloride,61,Chapter 21,Reactions of Amides,acid and amine,amine,1,amine,=,nitrile,62,Chapter 21,Lactam,Formation,Five-and six-,membered,rings can be formed by heating,-and-amino acids.,Smaller or larger rings do not form readily.=,63,Chapter 21,-,Lactams,Highly reactive,4-membered ring.,Found in antibiotics isolated from fungi.,Amide,ester!,=,64,Chapter 21,Synthesis of,Nitriles,1,amide,alkyl halide,diazonium,salt,aldehyde,or,ketone,cyanohydrin,=,65,Chapter 21,Reactions of,Nitriles,ketone,=,amide,acid,1,amine,66,Chapter 21,Thioesters,More reactive than esters because:,-,S-R is a better leaving group than,-,O-R,Resonance overlap is not as effective.,=,67,Chapter 21,Carbonic Acid Esters,CO,2,in water contains some H,2,CO,3,.,Diesters,are stable.,Synthesized from phosgene.,=,68,Chapter 21,Urea and Urethanes,Urea is the,diamide,of carbonic acid.,Urethanes are esters of a,monoamide,of carbonic acid.,=,氨基甲酸酯,69,Chapter 21,Polymers,Polycarbonates are long-chain esters of carbonic acid.,Polyurethanes are formed when a diol reacts with a,diisocyanate,.,=,二异氰酸盐,70,Chapter 21,End of Chapter 21,71,Chapter 21,