Carboxylic Acids: Crash Course Organic Chemistry #30

Summary

This Crash Course Organic Chemistry episode explores carboxylic acids, detailing their role in everyday smells like feet and vomit, and their importance in organic synthesis. Deboki Chakravarti explains how carboxylic acids can be synthesized from alcohols or aldehydes and their conversion into useful compounds like esters and acid chlorides. The video also touches on the historical discovery and synthesis of penicillin, highlighting its significance in medicine.

Takeaways

• 🧫 Carboxylic acids are responsible for unpleasant smells such as those from feet, underarms, vomit, and goats.
• 🦠 Bacteria play a role in producing carboxylic acids like isovaleric acid in feet and malodorous molecules in underarms.
• 🍫 Butyric acid, which causes the smell of vomit, is also found in rancid butter and is used in some foods to add flavor.
• 🥨 Some carboxylic acids like caproic, caprylic, and capric acids are associated with the smell of goats and are found in their milk.
• 🧪 Carboxylic acids can be synthesized from alcohols or aldehydes through oxidation or from Grignard reagents and carbon dioxide.
• 🔍 Carboxylic acids are named based on the longest carbon chain and suffix '-oic acid', with examples like ethanoic and propanoic acid.
• 📚 Carboxylic acids are the highest priority in naming compounds, taking precedence over other functional groups like ketones.
• ⚗️ Carboxylic acids are weak acids, partially ionizing in water to form a hydrogen ion and a carboxylate ion.
• 🔥 They have high boiling points due to intermolecular hydrogen bonding and are liquids at room temperature if they have fewer than ten carbons.
• 🧪 Shorter-chain carboxylic acids can form water-soluble salts when reacted with sodium or potassium hydroxide.
• 🌸 Carboxylic acids can be converted into pleasant-smelling esters through Fischer Esterification, a reaction used in perfumes.
• 💊 Acid chlorides, derived from carboxylic acids, are important in organic chemistry and were used in the synthesis of penicillin, the first mass-produced antibiotic.

Q & A

What is the connection between the smells of feet, underarms, vomit, and goats?

The connection is carboxylic acids. The smell of feet is partly due to isovaleric acid, underarms due to malodorous molecules including carboxylic acids, vomit due to butyric acid, and goats due to caproic, caprylic, and capric acids.

How is butyric acid related to the smell of vomit and cheese?

Butyric acid is produced by bacteria in our gut and causes the stench of vomit. It is also found in rancid butter and is a key part of the aroma of parmesan cheese.

Why might we want to work with carboxylic acids despite their unpleasant smells?

We can make nice-smelling compounds using carboxylic acids as a starting point and convert them into other useful compounds for organic synthesis.

How can we make a carboxylic acid?

We can make carboxylic acids by oxidizing alcohols or aldehydes with chromic acid or another suitable oxidizing agent, or by reacting Grignard reagents with carbon dioxide.

What is the systematic naming convention for carboxylic acids?

The naming convention involves looking at the structure, using the number of carbons in the longest chain, and adding the suffix '-oic acid'.

Why do carboxylic acids have high boiling points?

Carboxylic acids have high boiling points due to the formation of intermolecular hydrogen bonds between two acid molecules or an acid and water.

How can carboxylic acids be converted into water-soluble salts?

Shorter-chain carboxylic acids can be reacted with sodium or potassium hydroxide to form water-soluble salts.

What is the issue with using nucleophiles in reactions involving carboxylic acids?

Most basic nucleophiles tend to deprotonate carboxylic acids instead of attacking the carbonyl carbon.

How is Fischer Esterification used to convert carboxylic acids into pleasant-smelling esters?

Fischer Esterification is an acid-catalyzed reaction of a carboxylic acid with an alcohol to form an ester, which often has a pleasant smell.

What is the significance of acid chlorides in organic chemistry?

Acid chlorides, along with other carboxylic acid derivatives, are involved in many useful reactions in organic chemistry, including the synthesis of the first mass-produced antibiotic, penicillin.

How did the discovery of penicillin happen?

The microbiologist Alexander Fleming discovered penicillin when he noticed that a fungus had contaminated one of his petri dishes and killed the bacteria present.

What was the breakthrough that made mass production of penicillin possible?

Mary Hunt discovered a fungus, Penicillium chrysogenum, on a spoiled cantaloupe melon that produced 200 times more penicillin than the fungus Fleming found, enabling mass production.