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of the R group from the OR moiety in front of the name of the parent alkane after the -e from the parent alkane has been replaced by -oate.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 type of reaction is a saponification?
A saponification, also known as the hydrolysis of fats/glycerides, is the hydrolysis of an ester in base.
A hydroxide ion from the base nucleophilically attacks the ester carbonyl carbon and replaces the ester OR group, which leaves as an alcohol. In the case of glyceride hydrolysis, the fatty acid chains are hydrolyzed from the glyceride backbone by the same mechanism. The carbonyl carbons of the fatty acids are attacked by hydroxide and the glyceride backbone becomes the alcohol leaving group (glycerol).
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 occurs in an amide hydrolysis?
In an amide hydrolysis, the hydroxide ion from a base nucelophilically attacks the carbonyl carbon and replaces the amine which leaves as a neutral amine.
The product of an amide hydrolysis is a carboxylic acid and a neutral amine.
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.
Order the four acid derivatives (anhydrides, amides, esters, acid chlorides) from most reactive to least reactive in a nucleophilic substitution reaction and explain the reason for this order.
From most to least reactive:
Acid Chlorides > Anhydrides > Esters > Amides
Acid derivatives with better leaving groups are more reactive in a nucleophilic substitution. Chlorides are the best leaving groups and amides are the worst leaving groups.
Which would more readily occur, assuming that the same (OH-) nucelophile is attacking, conversion of an amide to a carboxylic acid or conversion of an ester to a carboxylic acid? Why?
An ester is converted to a carboxylic acid more readily.
The RO- group of the ester is a better leaving group than the amine group of the amide, resutling in the ester reacting more readily.
If there are large substituents near the carbonyl group of an acid derivative, how is the reactivity of the carbonyl carbon in a nucleophilic attack affected?
Overall reactivity is decreased.
Large substituents near the carbonyl carbon cause steric hindrance and block nucelophile access to the electrophilic carbon.
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.
In a nucleophilic substitution reaction, what makes the group bound to the acid derivative carbonyl carbon a better leaving group?
The ability of a group to stabilize negative charge makes it a better leaving group.
The chloride anion that is the leaving group of an acid chloride is electronegative and stabilizes negative charge well. Thus, acid chlorides react well in nucleophilic substitution. An amine does not stabilize negative charge well and is a poor leaving group.
