Acid Derivatives and Esters Flashcards
What is an acid chloride?
An acid chloride is an organic molecule consisting of an alkane chain with a chlorine bound to a terminal carbonyl carbon (a carbon double bonded to an oxygen).
To name an acid chloride, remove the -e from the end of the name of the parent alkane and replace it with -oyl chloride. Since an acid chloride is a terminal group (always position 1) it’s unnecessary to write 1-propanoyl chloride.
What is the name of this molecule?
[image of butanoyl chloride]
Butanoyl chloride.
To name an acid chloride, remove the -e from the end of the name of the parent alkane, and replace it with -oyl chloride.
What is an anhydride?
An anhydride is an organic molecule containing two carbonyl groups connected by an oxygen.
Symmetric anhydrides, where the groups bonded to the two carbonyls are identical, are named by removing the -e from the parent alkane and replacing it with -oic anhydride. Non-symmetrical anhydrides are named by alphabetically arranging the two parent alkanes, replacing the -e with -oic, followed by the word anhydride.
[ethanoic anhydride image
What is the name of this molecule?
Ethanoic propanoic anhydride.
Name non-symmetrical anhydrides by alphabetically arranging the two parent alkanes, replacing the -e with -oic, and follow with the word anhydride.
What is an amide?
An amide is an organic molecule consisting of an alkane chain with a carbonyl carbon (a carbon double bonded to an oxygen) with a nitrogen bound.
Amides are named by removing the -e from the parent alkane and replacing it with -amide. Carbon chains bound to the nitrogen should be named in front of the alkanamide name without spaces.
[butanamide image
What is the name of this molecule?
Methylethanamide.
To name an amide, remove the -e from the parent alkane and replace it with -amide. Carbon chains bound to the nitrogen should be named in front of the alkanamide name without a space.
What is an ester?
An ester is an organic molecule consisting of an alkane chain with a terminal carbonyl carbon with an -OR group bound.
Esters are named by putting the name of the R group from the OR moiety in front of the name of the parent alkane after the -e from the parent alkane has been replaced by -oate.
[methyl ethanoate image
What is the name of this molecule?
Propyl butanoate.
To name an ester, name the carbon chain R group that is bonded to the oxygen first. After a space, name the parent alkane, replacing the -e with -oate.
What physical property do all acid derivatives share?
All acid derivatives have dipole-dipole interactions due to the polar carbonyl bond.
How does the boiling point of an acid derivatives compare to that of an alkane with a similar carbon chain length?
The boiling point of the acid derivative is higher than that of the alkanes with a similar carbon chain length.
The dipole-dipole interactions of the carbonyl bond in acid derivatives results in higher boiling points for acid derivatives compared to their alkane counterparts.
What acid derivative can be converted into all of the other acid derivatives?
** kind of a complicated topic for one card: acid chlorides & anhydrides can be prepared from carboxylic acids, everything else (including carboxylic acids) can be prepared from acid chlorides
Acid chlorides can be converted into anhydrides, esters, and amides.
The chloride of an acid chloride is a good leaving group and can be replaced via nucleophilic attack with a deprotonated carboxylic acid to create an anhydride, a deprotonated alcohol to create an ester, and an amine to create an amide.
What type of reaction do all of the acid derivatives undergo?
All of the acid derivatives undergo nucleophilic substitution reactions.
Nucleophiles attack the carbonyl carbon and replace the group bonded to the carbonyl carbon that characterizes the acid derivative. For example, a nucleophilic attack on an acid chloride will replace the chlorine with the nucleophile.
What type of reaction is a Hoffman Rearrangement?
In a Hoffman Rearragnement, a primary amine is created from the rearrangement and decarboxylation of a primary amide.
This reaction ocurrs in base, proceeding through an isocyanate (O=C=N-R) itermediate. Overall, the R group attached to the carbonyl bonds to the amide nitrogen, and the carbonyl group is lost as carbon dioxide gas.
What product will this reaction form?
1-aminopropane (and carbon dioxide gas).
This reaction is a Hoffman Rearrangement. The R group bonds to the nitrogen, and the carbonyl group is lost as carbon dioxide gas.
What type of reaction is a transesterification?
In a transesterification, the OR group of an ester is replaced by a different OR’ group.
An alcohol containing the new R’ group is added to the original ester in acid. The alcohol oxygen nucleophilically attacks the carbonyl carbon, replacing the ester OR with the alcohol OR’. The original ester OR is protonated and leaves as an alcohol.
What is the product of this reaction?
Glycerol and three fatty acid chains.
This reaction is a saponification, also known as the hydrolysis of fats/glycerides. Hydroxide ion from the base nucelophilically attacks the carbonyl carbons and the backbone leaves as an alcohol.
What is the product of this reaction?
Propanoic acid and aminomethane (methylamine).
This is an amide hydrolysis. Hydroxide ion from the base nucleophilically attacked the amide carbonyl carbon. The primary amine was the leaving group.
Would the tert-Butyl groups on the following amide affect a nucelophilic attack at the carbonyl carbon? If so, how would the groups affect reactivity?
No.
The tert-Butyl groups are far from the carbonyl carbon and will not cause steric hindrance that would hinder nucleophilic attack.
Does a carboxylate anion (COO-) or a alkoxide anion (RO-) stabilize negative charge more effectively? Based on this, are anhydrides or esters more reactive in nucleophilic substitution reactions?
The carboxylate anion stabilizes negative charge more effectively through resonance involving the two electronegative oxygen atoms. This makes the carbozylate anion a better leaving group and anhydrides more reactive in nucleophilic substitution reactions.
In a hydrolysis, how does the reactivity of a straight chain amide compare to that of a cyclic amide such as ß-lactam (below)?
The ß-lactam is much more reactive in a hydrolysis due to the significant ring strain that is relieved upon hydrolysis.
The carbon-nitrogen bond in an amide also has partial double bond character due to resonance. This increases ring strain in cyclic amides because it keeps rings from bending.
What is a keto acid?
A keto acid is an organic molecule containing a ketone group and a carboxylic acid group.
Keto acids with the ketone group on the carbon alpha to the carboxylic acid carbon are called alpha keto acids (also known as 2-oxoacids). Beta keto acids (also known as 3-oxoacids) have the ketone group on the beta carbon. Keto acids are named by indicating the location of the keto group and naming the keto group before naming the carboxylic acid chain.
What is the name of this molecule?
ß-ketobutanoic acid (also 3-oxobutanoic acid).
Keto acids are named by identifying the location of the ketone group relative to the carboxylic acid carbon (alpha, beta, gamma) and placing this in front of the carboxylic acid name. Keto acids are also named as oxoacids with a number indicating the number of carbons from the carboxylic carbon to the ketone carbon (inclusive). After the number and the prefix oxo-, the name of the carboxylic acid is used.
What type of keto acids readily undergo decarboxylation when heated?
ß-keto acids.
The carboxylic acid group is lost as carbon dioxide, and the reaction intermediate of the remaining chain is stabilized by the enol form.
What is the product of this reaction?
2-butanone and carbon dioxide gas.
The ß-keto acid undergoes a decarboxylation, losing the carboxylic carbon as CO2.
What type of reaction is acetoacetic ester synthesis?
Acetoacetic ester synthesis synthesizes a new ketone from acetoacetic ester.
The alpha carbon of acetoacetic ester can lose its acidic proton, forming a carbanion that can attack the R group in a haloalkane. The resulting molecule has an R group added to the alpha carbon of acetoacetic ester. This molecule can be hydrolyzed to a ß-keto acid. Heating the ß-keto acid results in a decarboxylation.
What is the product of this reaction? What can be done to the product to convert it to 2-pentanone?
ethyl 3-oxo-2-ethyl-butanoate.
This is an acetoacetic ester synthesis reaction. The ethyl 3-oxo-2-ethyl-butanoate can be hydrolyzed to a ß keto acid. This can then be decarboxylated to yield 2-pentanone.
What special chemistry does the alpha proton of a ß keto ester have and why?
Alpha protons of ß keto ester are acidic.
When the alpha proton is deprotonated, the resulting molecule is stabilized by resonance. Alpha protons of carbonyl compounds are acidic and the electronic stabilization of two carbonyl groups of ß keto esters make alpha protons even more acidic.
How does alpha hydrogen acidity contribute to acetoacetic ester synthesis?
The acidity of the alpha hydrogens of acetoacetic ester facilitates carbanion formation on the alpha carbon. This alpha carbon can then attack a haloalkane R group and the R group to the acetoacetic ester.
What is the enol form of the following ester?
The following is the enol form of the ester.
