20.9 Properties, Synthesis, and Reactions of Carboxylic Acids | Organic Chemistry

Chad's Prep
13 Apr 202113:58
EducationalLearning
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TLDRThis video script provides an in-depth look at the synthesis and reactions of carboxylic acids, a fundamental topic in organic chemistry. The lesson begins with a review of the properties of carboxylic acids, emphasizing their acidity with typical pKa values around four to five. It then delves into the boiling point differences due to hydrogen bonding, illustrating the significant increase in boiling point for carboxylic acids compared to ketones and alcohols. The script covers various synthesis methods for carboxylic acids, including ozonolysis of alkenes and alkynes, oxidation of primary alcohols using chromic acid, and the use of Grignard reagents with carbon dioxide. Additionally, it discusses the conversion of carboxylic acids into acyl halides, esters, amides, and the reduction to primary alcohols using lithium aluminum hydride or borane. The lesson concludes with a reminder of the importance of understanding these reactions for a comprehensive grasp of organic chemistry.

Takeaways
  • 🔍 Carboxylic acids are characterized by their acidity with typical pKa values ranging from 4 to 5, such as acetic acid.
  • 🌡️ The boiling point of carboxylic acids is higher than might be predicted due to hydrogen bonding, which allows them to form dimers.
  • ⚖️ Ozonolysis of alkenes and alkynes under oxidizing conditions can lead to the synthesis of carboxylic acids.
  • 🍾 Oxidation of primary alcohols using strong reagents like chromic acid can produce aldehydes and further oxidize them to carboxylic acids.
  • 🔥 The Villiger oxidation can convert aldehydes to carboxylic acids using a peroxy acid like mCPBA.
  • 🌿 Side chain oxidation of aromatic compounds with hot potassium permanganate or chromic acid can oxidize benzylic carbons to carboxylic acids.
  • 🧪 Carboxylic acid derivatives, including nitriles, can be converted to carboxylic acids by adding H3O+.
  • ⚛️ Grignard reagents can react with carbon dioxide to form carboxylic acids after an acid workup step.
  • 🔬 Carboxylic acids can be transformed into acyl halides, esters, amides, and can undergo acid-base reactions to form conjugate bases or carboxylate ions.
  • ⛓ The conversion of carboxylic acids to other functional groups often involves acid-catalyzed reactions.
  • 🧪 Lithium aluminum hydride (LiAlH4) can reduce carboxylic acids to primary alcohols, unlike sodium borohydride (NaBH4) which is less effective for this transformation.
Q & A

  • What is the typical pKa range for carboxylic acids like acetic acid?

    -The typical pKa range for carboxylic acids like acetic acid is between 4 and 5.

  • Why do carboxylic acids have a higher boiling point compared to ketones and alcohols with a similar molecular size?

    -Carboxylic acids have a higher boiling point due to the ability to form two sets of hydrogen bonds between molecules, leading to dimerization and increased intermolecular forces.

  • What are the products of ozonolysis under oxidizing conditions with an alkene?

    -Under oxidizing conditions, ozonolysis of an alkene can produce a carboxylic acid and a ketone, depending on the substitution pattern of the alkene.

  • How does the oxidation of a primary alcohol with chromic acid differ from oxidation with PCC?

    -Chromic acid oxidizes a primary alcohol to a carboxylic acid in two steps, converting it first into an aldehyde and then into a carboxylic acid. In contrast, PCC stops the oxidation at the aldehyde stage.

  • What is the role of hot concentrated KMnO4 in the oxidative cleavage of alkenes?

    -Hot concentrated KMnO4 can be used to cleave alkenes oxidatively, leading to the formation of carboxylic acids and ketones, depending on the substitution of the alkene.

  • What happens when you perform ozonolysis on a terminal alkyne?

    -When ozonolysis is performed on a terminal alkyne, the terminal carbon ends up as carbon dioxide, which is not a carboxylic acid.

  • How can you synthesize a carboxylic acid from an aldehyde using the Baeyer-Villiger oxidation?

    -An aldehyde can be converted into a carboxylic acid using the Baeyer-Villiger oxidation with a peroxy acid, most commonly MCPBA.

  • What is the requirement for the benzylic carbon in side chain oxidation to be oxidized to a carboxylic acid?

    -For the benzylic carbon to be oxidized to a carboxylic acid, it must have at least one hydrogen atom. If it's quaternary (no hydrogens), the reaction will not occur.

  • How do you convert a carboxylic acid derivative into a carboxylic acid?

    -Any carboxylic acid derivative can be converted into a carboxylic acid by adding H3O+ (a proton).

  • What is a new method introduced for synthesizing carboxylic acids involving Grignard reagents?

    -A new method for synthesizing carboxylic acids involves the addition of a Grignard reagent to carbon dioxide, followed by an acid workup to protonate and form the carboxylic acid.

  • What type of reaction is used to convert a carboxylic acid into an ester?

    -The Fischer esterification, an acid-catalyzed reaction, is used to convert a carboxylic acid into an ester.

  • Which reagent is suitable for the reduction of a carboxylic acid to a primary alcohol?

    -Lithium aluminum hydride (LiAlH4) is suitable for the reduction of a carboxylic acid to a primary alcohol.

Outlines
00:00
🔍 Carboxylic Acids: Properties, Synthesis, and Reactions Overview

This paragraph introduces the topic of carboxylic acids, focusing on their synthesis and reactions. It mentions a quick review of properties such as acidity and boiling points, where carboxylic acids exhibit higher boiling points due to hydrogen bonding, leading to dimerization. The lesson is part of an organic chemistry series released weekly, and viewers are encouraged to subscribe for updates. The importance of carboxylic acids as a functional group with typical pKa values in the range of four to five is highlighted, using acetic acid as an example.

05:03
🧪 Synthesis of Carboxylic Acids through Various Reactions

The paragraph delves into the synthesis of carboxylic acids through several reactions, starting with ozonolysis of alkenes and alkynes, which leads to oxidative cleavage and the formation of carboxylic acids under oxidizing conditions. It also covers the oxidation of primary alcohols to carboxylic acids using strong oxidizing agents like chromic acid, and the oxidation of aldehydes to carboxylic acids using chromic acid or the Baeyer-Villiger oxidation with peroxy acids like mCPBA. Additionally, side chain oxidation of aromatic compounds with hot potassium permanganate or chromic acid is discussed as a method to synthesize carboxylic acids. The paragraph concludes with the introduction of a new method involving the conversion of nitriles into carboxylic acids using H3O+ and the mechanism behind this reaction.

10:03
🧪 Further Synthesis Methods and Reactions of Carboxylic Acids

This paragraph explores additional methods for synthesizing carboxylic acids, including the use of Grignard reagents and their reaction with carbon dioxide to form carboxylic acids. It also reviews the reactions of carboxylic acids, such as their conversion into acyl halides, esters, and amides through acid-catalyzed reactions. The concept of nucleophilic acyl substitution is touched upon, and the use of lithium aluminum hydride (LiAlH4) for the reduction of carboxylic acids to primary alcohols is discussed. The paragraph concludes with an alternative reduction method using borane and an invitation for viewers to like, share, and check out the speaker's premium course for further study materials.

Mindmap
Keywords
💡Carboxylic Acids
Carboxylic acids are organic compounds that contain a carboxyl functional group (-COOH). They are characterized by their acidic nature and are typically measured by their pKa values, which are in the range of four to five for common examples like acetic acid. In the video, the properties of carboxylic acids, including their acidity and boiling points, are discussed in the context of organic chemistry.
💡Boiling Point
The boiling point of a substance is the temperature at which it changes from a liquid to a gas. The video mentions that carboxylic acids have higher boiling points than other compounds of similar molecular weight due to stronger intermolecular forces, specifically hydrogen bonding. This is illustrated by comparing the boiling points of acetone, an alcohol, and a carboxylic acid.
💡Hydrogen Bonding
Hydrogen bonding is a type of intermolecular force that occurs when a hydrogen atom is bonded to a highly electronegative atom and is attracted to another electronegative atom in a different molecule. In the context of the video, hydrogen bonding is responsible for the high boiling points of carboxylic acids, as they can form multiple hydrogen bonds with neighboring molecules.
💡Ozonolysis
Ozonolysis is a chemical reaction in which ozone (O3) reacts with a double bond in a molecule, leading to the cleavage of the bond. In the video, ozonolysis is discussed as a method for synthesizing carboxylic acids from alkenes and alkynes under oxidizing conditions, which involves the use of hydrogen peroxide or hot concentrated potassium permanganate.
💡Oxidation
Oxidation is a chemical process that involves the loss of electrons or an increase in oxidation state. The video covers the oxidation of primary alcohols to carboxylic acids using strong oxidizing agents like chromic acid, as well as the oxidation of aldehydes to carboxylic acids, which is part of the synthesis process for these compounds.
💡Villiger Oxidation
Villiger oxidation is a chemical reaction that involves the conversion of a ketone to an ester or an aldehyde to a carboxylic acid using a peroxy acid, commonly m-chloroperoxybenzoic acid (MCPBA). The video briefly mentions this reaction as an alternative method for converting aldehydes to carboxylic acids, although it is more commonly associated with the conversion of ketones to esters.
💡Side Chain Oxidation
Side chain oxidation refers to the process of oxidizing a side chain or substituent in a molecule, often in the context of aromatic compounds. The video discusses how benzylic carbons (carbons adjacent to a benzene ring) can be oxidized to carboxylic acids using reagents like hot potassium permanganate or chromic acid.
💡Grignard Reagent
A Grignard reagent is an organomagnesium compound typically prepared by reacting an alkyl or aryl halide with magnesium metal. In the video, Grignard reagents are shown to be versatile in organic synthesis, including their use in the synthesis of carboxylic acids through the reaction with carbon dioxide, followed by an acid workup.
💡Acyl Halides
Acyl halides are compounds that contain a carbonyl group bonded to a halogen atom. They are derived from carboxylic acids and are used in various chemical reactions. The video mentions the conversion of carboxylic acids to acyl halides using reagents like thionyl chloride (SOCl2) or phosphorus tribromide (PBr3).
💡Esterification
Esterification is a chemical reaction that produces an ester from a carboxylic acid and an alcohol, typically in the presence of an acid catalyst. The video discusses Fischer esterification, an acid-catalyzed reaction, as a method for converting carboxylic acids into their corresponding esters.
💡Amides
Amides are a class of organic compounds derived from carboxylic acids, containing a carbonyl group bonded to a nitrogen atom. The video briefly touches on the formation of amides from carboxylic acids through an acid-catalyzed reaction with an amine, although this is not a primary focus of the lesson.
💡Hydride Reduction
Hydride reduction refers to the use of hydride reagents, such as lithium aluminum hydride (LiAlH4) or borane (BH3), to reduce a compound. In the context of the video, it is mentioned that carboxylic acids can be reduced to primary alcohols using lithium aluminum hydride, which is a key reaction in organic synthesis.
Highlights

Carboxylic acids are acids with typical pKas in the range of four to five, such as acetic acid.

Boiling points of carboxylic acids are significantly higher than ketones or alcohols of similar molecular weight due to hydrogen bonding and dimerization.

Ozonolysis can be used to synthesize carboxylic acids from alkenes and alkynes under oxidizing conditions.

Primary alcohols can be oxidized to carboxylic acids using strong reagents like chromic acid.

The Villiger oxidation can convert aldehydes to carboxylic acids using a peroxy acid like mCPBA.

Side chain oxidation of aromatic compounds with hot potassium permanganate or chromic acid can yield carboxylic acids at the benzylic position.

Carboxylic acid derivatives, including nitriles, can be converted to carboxylic acids by the addition of H3O+.

Grignard reagents can be used to synthesize carboxylic acids via nucleophilic addition to carbon dioxide followed by an acid workup.

Carboxylic acids can be converted into acyl halides, esters, and amides using acid catalysis.

Hydrazine (Borane) can reduce carboxylic acids to primary alcohols through a mechanism that differs from standard nucleophilic acyl substitution.

Lithium aluminum hydride is used for the reduction of carboxylic acids to primary alcohols, as sodium borohydride is not effective for this transformation.

The lesson is part of an organic chemistry playlist released weekly throughout the school year.

Subscribing to the channel and clicking the bell notification ensures viewers are notified of new lesson posts.

Differentiating between oxidizing and reducing conditions in ozonolysis leads to the production of either aldehydes/ketones or carboxylic acids.

The synthesis of carboxylic acids from nitriles involves the protonation of the nitrogen and nucleophilic attack by water molecules.

Grignard addition to carbon dioxide is a novel method introduced for the synthesis of carboxylic acids.

Acid-base reactions with carboxylic acids result in the formation of the corresponding conjugate base or carboxylate ion.

The study guide and practice problems for carboxylic acids and their derivatives are available in the premium course at chadsprep.com.

Transcripts

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Related Tags
Carboxylic AcidsOrganic ChemistryOzonolysisAcidityBoiling PointHydrogen BondingAlkenesAlkynesOxidationAlcoholsChromic AcidPCCVilliger OxidationBenzylic CarbonAcid HalidesEstersAmidesNucleophilic SubstitutionGrignard ReagentsCarbon DioxideHydride ReductionBorane