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[PDF] Carboxylic acid Derivatives
The most important acid derivatives are esters, amides and nitriles, although acid halides and anhydrides are also derivatives (really activated forms of a
[PDF] Chapter 21: Carboxylic Acid Derivatives
all derivatives of carboxylic acids: amides is due to the strong dipolar forces that The reactivity of acid derivatives can be correlated
[PDF] Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution 201
derivative (amides and esters) are more readily prepared from more reactive acyl derivatives (acid chlorides and anhydrides) carboxylic acid amide
[PDF] 100 Chapter 21 Carboxylic Acid Derivatives and Nucleophilic Acyl
Amides: Primary amides (RCONH2) are named as the carboxylic acid except the -ic acid ending is replaced with -amide or the -carboxylic acid ending is replaced
[PDF] 18H-acid derivativespdf
Since the acid chloride is more reactive than the anhydride, ester or amide, the acid chloride can be converted directly to any of these acyl derivatives
[PDF] unit (9) carboxylic acids, esters, amines, and amides
Esters are derivative of carboxylic acids in which the –OH group on the carboxyl has been replaced with an –OR group Esterification (Preparation of Esters)
[PDF] sch_206-amidespdf
An amide is a composite of a carboxylic acid and either ammonia or an amine R may be H, alkyl or aryl Amides are derivatives of carboxylic acids, derived by
[PDF] 85 Chapter 20: Carboxylic Acid Derivatives: Nucleophilic Acyl
amide acid chloride acid anhydride
[PDF] Functional Derivatives of Carboxylic Acids
Esters and amides, however, are universally present Amide Ester Anhydride Acid halide Increasing reactivity toward nucleophilic acyl substitution R O
[PDF] Chapter 21: Carboxylic Acid Derivatives
all derivatives of carboxylic acids: R acid ester anhydride acyl halides amides compounds with groups that can be Interconversion of Acid Derivatives (21-5)
[PDF] Derivatives of carboxylic acids
Derivatives of carboxylic acids Vladimíra can be oxidized to oxo derivatives (= dehydrogenation) products of esterification (acid + alcohol → ester + water)
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8011_2chapter_21_acid_derivatives.pdf Chapter 21:Chapter 21:
Carboxylic Acid DerivativesCarboxylic Acid DerivativesCarboxylic Acid DerivativesCarboxylic Acid Derivatives
284?Class I carbonyl compounds are those that will react by acyl substitutions. They are all derivatives of carboxylic acids: RH O RR O cannot be replaced by a nucleophile 285
Class II
aldehydeketone R OH O ROR O RO O RX O RNH2 OO R carboxylic acidesteranhydrideacyl halides amidescompounds with groups that can be replaced by a nucleophileClass I
?Physical Properties (21-3) ?Boiling points increases with the strength of the dipolar interactions. 286?The large boiling points of nitriles, acids and amides is due to the strong dipolar forces that are found in these compounds.
287?Interconversion of Acid Derivatives(21-5)
Acid derivatives normally react by nucleophilic
acyl substitution. The general mechanism of this process is given below. Following this mechanism, it is possible to transform one acid derivative into another one. 288?The reactivity of acid derivatives can be correlated to the leaving group ability of the base that is expelled. The better the leaving group, the more reactive will be the acid derivative. Not surprising
that acid chloride are the most reactive derivatives. 289?This is the reason ketones and aldehydes will not react by acyl substitutions. The leaving group is either R -or H-, which are very basic, therefore poor leaving groups OO 290
RH poor leaving groups
?In theory, it is possible to go from one acid derivatives to another one. In practice, only the following reactions are normally used.
Rule: a more
Rule: a more
reactive intermediate can be converted into a less reactive one. 291Conversion of Acid Chloride to AnhydrideConversion of Acid Chloride to Anhydride 292
Conversion of Acid Chloride to EstersConversion of Acid Chloride to Esters 293
Conversion of Acid Chloride to AmidesConversion of Acid Chloride to Amides 294
Conversion of Anhydrides to EstersConversion of Anhydrides to Esters 295
Conversion of Anhydrides to AmidesConversion of Anhydrides to Amides 296
Practice QuestionsPractice Questions
?If you were starting with acetyl chloride, what nucleophile would you use to prepare the following compounds.
O O 297NHCH2CH3
O ?Write a detailed stepwise mechanism of the reaction taking place between acetyl chloride and water. 298Conversion of Esters to Amides Conversion of Esters to Amides ((AmmonolysisAmmonolysis)) 299
?In all of these reactions, the key feature was the basicity of the nucleophile and leaving group. If the nucleophile is more basic than the leaving group, the reaction will proceed. However, if the nucleophile is less basic than the leaving group, no reaction will occur. Hence, knowing pKa is important.
NH2 ONaClCl
O NaNH2 300this reaction will not proceed since Cl- is a weaker base than NH 2- Cl O
NaNH2NH2
O NaCl however this reaction is easy since the leaving group Cl -is a weaker base than NH 2- •Transesterification(21-6)This reaction is very similar to the hydrolysis
reaction (see 21-7). The only difference is that an alcohol is used in large excess instead of water. This results in the formation of a new ester, one that has the structure of the alcohol that was used in excess. The reaction can be performed under basic or acidic conditions, the latter being more common.common. 301Mechanism of Mechanism of TransesterificationTransesterification 302
?Hydrolysis of Acid Derivatives(21-7)
This reaction is the reason all of these
compounds are considered acid derivatives...because they produce carboxylic acids upon hydrolysis. This reaction can be performed under acidic or basic conditions. Acid Chlorides/AnhydridesAcid Chlorides/AnhydridesThese two compounds are so reactive that the
hydrolysis can be performed under neutral conditions. 303Esters
Esters can be hydrolyzed under acidic or
basic conditions. Under basic conditions, the reaction is known as " saponification" 304?Under acidic conditions, the mechanism of hydrolysis is the reversed of the Fisher Esterification. H + OCH3 OH+OH OCH3 OH H + OH OCH3 OH H+ OCH3 O H2O 305
OH O B-H OH OCH3 OH+ HH+B- OH O
Amides
Amides also hydrolyze to acids
under basic or acidic conditions. 306Base Catalyzed Hydrolysis of AmidesBase Catalyzed Hydrolysis of Amides 307
Acid Catalyzed Hydrolysis of AmidesAcid Catalyzed Hydrolysis of Amides 308
Nitriles
Nitriles are considered acid derivatives
because they generate the corresponding acids under hydrolysis conditions.Reactions can be performed under acidic
or basic conditions. 309Base Catalyzed Hydrolysis of Base Catalyzed Hydrolysis of NitrilesNitriles 310
Practice QuestionPractice Question
?What product would be formed from the acid- catalyzed hydrolysis of the following esters? 311•Reduction(21-8)
Like other compounds bearing C=O functions,
acid derivatives can be reduced easily using reagents such as (LiAlH4). The majority of the
reductions of acid derivatives give the corresponding primary alcohols. Aldehydes and amines can also be generated. Esters(formation of 1o alcohol)Esters(formation of 1o alcohol) 312Mechanism of Ester ReductionMechanism of Ester Reduction 313
Acid Chlorides
They can be reduced to the
corresponding primary alcohols with LiAlH4. However, the use of a bulkier
reagent prevents the reduction to continue past the aldehyde product. 314Amides(formation of amines)
Amides are reduced to 1
o, 2oor 3oamines with LiAlH 4. 315Mechanism of Amide ReductionMechanism of Amide Reduction 316
Nitriles
In a similar reactions, nitriles can also be
reduced to the corresponding primary alcohols. 317?Reactions of Acids Derivatives with Grignards (21-9)
We have seen that esters and acid chlorides add
two equivalents of Grignard reagent to give tertiary alcohols. 318Nitriles
Nitriles also react with Grignard reagent
to give the corresponding imine. Under acidic conditions, imines are easily converted to the corresponding ketones (see Chapter 18-16) 319SummarySummary: Acid Chlorides (21: Acid Chlorides (21--10)10) 320
321
SummarySummary: Anhydrides (21: Anhydrides (21--11)11) 322