Chapter 16: Esters – Flashcards
Unlock all answers in this set
Unlock answersquestion
Ester
answer
Carboxylic acid derivative. The -OH of the carboxylic acid is replaced with an -OR group -The simplest ester has 2 C atoms -The simplest aromatic ester is derived from benzoic acid
question
Preparation of Esters
answer
Produced through a process called esterification
question
Esterification Reaction
answer
Reaction of carboxylic acid with an alochol (or phenol) to produce an ester and water This reaction is an example of a condensation reaction Requires a strong acid catalyst, like H2SO4 (sulfuric acid)
question
Cyclic Esters
answer
Hydroxy acids contain both a hydroxyl (-OH) and a carboxyl (C=O) group -Have the ability to undergo intramolecular esterification to form cyclic esters -Internal esterificiation takes place in situations where a 5 or 6 membered ring can be formed (they are the most stable rings)
question
Naming Esters
answer
1. Determine the name for the alkyl and acyl part of the ester -the alkyl part appears first followed by a separate word for the acyl part 2. The alkyl part of the ester is simply the name of the R group 3. The acyl part of the ester is obtained by dropping the -ic acid ending for the caboxylic acids name and adding -ate
question
Flavor and Fragrance of Esters
answer
Esters are responsible for the flavor and fragrance of fruits and flowers -The structure of esters in natural flavors are closely related to each other.
question
Isomers for Carboxylic Acids and Esters
answer
Carboxylic acids exhibit skeletal isomerism Esters exhibit positional isomerism Functional group isomers - carboxylic acids and esters with the same number of carbon atoms and the same degree of saturation
question
Physical Properties of Esters
answer
Ester molecules do not form H bonds with each other as they do not have a hydrogen atom bonded to an oxygen atom -Have lower boiling points than those of alcohols and acids Lower molecular weight esters are soluble in water because they can form H bonds with water molecules -Solubility decreases with increasing carbon chain lengths
question
Chemical Reactions of Esters
answer
The reverse reaction -Ester Hydrolysis *Saponification reaction
question
Ester Hydrolysis
answer
Ester reacts with water, producing the carboxylic acid and alcohol from which the ester was formed -Reverse of esterification -Requires a strong catalyst or enzyme
question
Saponification reaction
answer
Hydrolysis of an organic compound, under basic conditions, in which a carboxylic acid salt is one of the products -esters, amides, and fats and oils undergo saponification reactions
question
Thioester
answer
Sulfur containing analog of an ester in which an -SR group has replaced the -OR group
question
Acetyl Coenzyme A
answer
Most important naturally occurring thioester -Plays a central role in the metabolic cycles of the body to obtain energy to run itself
question
Condensation Polymers
answer
Formed when difunctional monomers are linked together via condensation reactions with the production of by-product water molecules -Polyesters are condensation polymers Dicarboxylic acids and dialcohols are used for the formation of polyesters -Important polymers - lactomer
question
Lactomer
answer
Used as surgical staples because of its biodegradable nature Dissolves after several weeks, and the by-products formed are lactic acid and glycolic acid, both of which are readily metabolized within the human body
question
Acid Chloride
answer
Carboxylic acid derviative in which the -OH portion of the carboxyl group has been replaced with a -Cl atom
question
Naming an Acid Chloride
answer
1. Replace the -ic acid ending of the common name of the parent carboxylic acid with -yl chloride ex. Butyric acid becomes butyryl chloride 2. Replace the -oic acid ending of the IUPAC name of the parent carboxylic acid with -oyl chloride ex. : 3-methylpentanoic acid becomes 3-methylpentanoyl chloride
question
Acid Chloride Preparation
answer
Parent carboxylic acid is made to react with an inorganic chloride Useful starting material for the synthesis of other carboxylic acid derivatives such as esters and amides
question
Acid Anhydride
answer
Carboxylic acid derivative in which the -OH portion of the carboxyl group has been replaced with an acyl group Types: -Symmetrical acid anhydrides -Mixed anhydrides
question
Acyl Transfer Reactions
answer
Chemical reactions in which acyl groups are transferred from one mlecule to another Compounds with acyl groups, when made to react with an alcohol or phenol, result in the formation of an ester Carboxylic acids, acid chlorides, and acid anhydrides contain acyl groups
question
Esters and Anhydrides of Inorganic Acids
answer
Inorganic acids such as sulfuric, phosphoric, and nitric acids react with alcohols to form esters -similar to carboxylic acids and their derivatives Phosphate esters are the most important inorganic esters, from a biochemical standpoint - they are formed by the reaction of an alcohol with phosphoric acid
question
Nitroglycerin
answer
Inorganic triester of glycerol -used for making explosives -used to treat heart related diseases
question
Phosphoric acid anhydrides
answer
Undergo esterification reactions with alcohols -Produce diphosphate monoester and triphosphate monoester -ex. -->Adenosine diphosphate (ADP) -->Adenosine triphosphate (ATP) Biologically important phosphoric acids -Phosphoric acid -Diphosphoric acid -Triphosphoric acid
