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Carboxylic Acids

• Carboxylic acids are organic compounds with a carboxyl group (-COOH)
• Many carboxylic acids are colorless liquids with unpleasant odors
• Carboxylic acids with 5 to 10 carbon atoms have a characteristic "goaty" odor
• Acids with more than 10 carbon atoms are wax-like solids
• Carboxylic acids exhibit strong hydrogen bonding between molecules
• Therefore, they have high boiling points compared to compounds of comparable molar mass
• Carboxylic acids are named by replacing the suffix (-e) with -oic acid
• Carboxylic acids are typically weak acids
• They partially dissociate in water to form H+ ions and RCOO- anions
• Acetic acid has a pKa of 4.76 in water meaning that in a 1.0 M solution, about 0.4% of the acid groups will be dissociated to form the carboxylate.

Esters

• Esters are colorless and volatile liquids with pleasant odors
• They have distinctive fruit-like odors and many occur naturally in essential oils of plants
• Esters are derived from carboxylic acids
• The -OH group of the carboxylic acids is converted to an -OR in an ester
• Esters have lower boiling points than carboxylic acids due to the lack of hydrogen bonding
• Small esters are fairly soluble in water, but solubility decreases with increasing chain length
• Esters consist of two words: the name of the alkyl group R' of the ester group ending with -yl, followed by the name of the parent acid with the family-name ending -ic acid replaced by -ate

Amides

• Compounds with a nitrogen directly attached to the carbonyl carbon are called amides
• The nitrogen of an amide may be unsubstituted (-NH2), monosubstituted (-NHR), or disubstituted (-NR2)
• Amides are typically solids, with the exception of formamide (HCONH2) which is a liquid
• Amides are not basic like amines
• Amides with an unsubstituted —NH2 group are named by replacing the -ic acid or -oic acid of the corresponding carboxylic acid with -amide
• If the nitrogen atom has alkyl substituents, the compound is named by specifying the alkyl group and then identifying the amide name
• The alkyl substituents are preceded by the letter "N" to identify them as being attached directly to nitrogen

Reactions of Carboxylic Acids

• Ester synthesis: The conversion of carboxylic acids to esters using acid and alcohol is called the Fischer Esterification
• Amide synthesis: The amide bond can be synthesized from a carboxylic acid and an amine
• This reaction does not proceed easily because the amine is a base and will deprotonate the acid
• Heating to a high temperature (typically >160 °C) is required to form the amide product
• Hydrolysis of esters and amides: Esters and amides can be hydrolyzed to yield back the parent carboxylic acid and corresponding alcohol or amine.
• The equilibrium of this reaction can be pushed towards the acid by adding an excess of water
• The most well-known hydrolysis reaction is saponification, in which triglycerides (fats) are reacted with sodium hydroxide to yield fatty acids and glycerol
• Amides are considerably more stable than esters and can only undergo hydrolysis in acid-catalyzed reactions
• The reactivity of carboxylic acids and their derivatives depends on the basic strength of the acyl-bound substituent.

Applications of Carboxylic Acids

• Salicylic acid: It is an organic carboxylic acid derived from the metabolism of salicin produced in willow bark
• Acetyl Salicylic Acid (Aspirin): It is produced by the esterification of salicylic acid with acetic anhydride
• Opiates: Morphine, heroin, and codeine are all examples of drugs from the opiate family
• Heroin: Morphine is esterified with acetic acid to yield heroin
• Codeine: An opiate where the ester is replaced by an ether

Explore the fascinating world of carboxylic acids and esters in this quiz. Discover their properties, naming conventions, and the significance of their chemical structures. Test your knowledge on their characteristics, behavior in water, and their unique odors.