Functional Groups 4
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Questions and Answers

What kind of intermolecular forces are primarily responsible for the liquid state of alcohols?

  • Hydrogen bonds (correct)
  • Ionic bonds
  • Covalent bonds
  • Van der Waals forces

    • How does the solubility of alcohols change with an increase in the length of the carbon chain?

  • Solubility in water becomes very high
  • Solubility in water remains constant
  • Solubility in water decreases (correct)
  • Solubility in water increases significantly

    • Which characteristic is true for alcohols in biological systems?

  • They serve as a primary source of energy
  • They are highly toxic and not soluble in water
  • They inhibit all enzyme activity
  • They can act as both weak acids and weak bases (correct)

    • What is the product formed when a primary alcohol undergoes oxidation?

    <p>Aldehyde</p> Signup and view all the answers

    Which type of alcohol is most resistant to oxidation?

    <p>Tertiary alcohol</p> Signup and view all the answers

    What characteristic of low molecular mass aldehydes and ketones contributes to their solubility in water?

    <p>They can form hydrogen bonds with water.</p> Signup and view all the answers

    Which statement accurately describes the reactivity of aldehydes compared to ketones?

    <p>Aldehydes can be oxidized while ketones cannot.</p> Signup and view all the answers

    In the reaction between a nucleophile and an aldehyde, what is formed after the nucleophile donates its electron pair?

    <p>A carbon-oxygen bond with a hydroxyl group.</p> Signup and view all the answers

    Why are ketones generally stable to oxidation, unlike aldehydes?

    <p>Ketones do not have a hydrogen atom directly bonded to the C=O carbon.</p> Signup and view all the answers

    What effect does adding an acid have on the reactivity of the C=O bond in aldehydes and ketones?

    <p>It makes the carbonyl more reactive towards nucleophiles.</p> Signup and view all the answers

    After reduction, what is the product obtained from aldehydes and ketones?

    <p>Alcohols</p> Signup and view all the answers

    Which reaction is characterized by the conversion of a C=O bond to a C=N bond?

    <p>Nucleophilic addition by an amine.</p> Signup and view all the answers

    What role do aldehydes and ketones play in biological systems?

    <p>They participate in enzyme reactions and drug interactions.</p> Signup and view all the answers

    What is the reason for supplying many acidic drugs as salts?

    <p>To enhance their water solubility</p> Signup and view all the answers

    Which statement best describes the boiling points of esters compared to amides?

    <p>Amides have higher boiling points due to their ability to form hydrogen bonds.</p> Signup and view all the answers

    What factor decreases the water solubility of esters and amides?

    <p>Increased molecular weight</p> Signup and view all the answers

    What type of reaction primarily characterizes the reactivity of carboxylic acids?

    <p>Nucleophilic substitution</p> Signup and view all the answers

    What is true about the oxidation of carboxylic acids under normal conditions?

    <p>They are resistant to oxidation.</p> Signup and view all the answers

    Which of the following statements about amides is correct?

    <p>Amides are classified as 1º, 2º, or 3º based on nitrogen substitution.</p> Signup and view all the answers

    How does the ability to form hydrogen bonds affect the solubility of amides in water?

    <p>It increases their solubility.</p> Signup and view all the answers

    What is the significance of hydrolysis in the context of esters and amides?

    <p>It is a key reaction mechanism for nucleophilic substitution.</p> Signup and view all the answers

    What is the general formula for alcohols and how does it contribute to their physical properties?

    <p>The general formula for alcohols is R-OH, which allows them to form hydrogen bonds, resulting in low molar mass alcohols being liquids.</p> Signup and view all the answers

    Explain the trend in water solubility of alcohols as the R group increases in length.

    <p>As the R group increases in length, alcohols become less soluble in water due to the hydrophobic nature of the longer carbon chains.</p> Signup and view all the answers

    Describe the oxidation products of a primary alcohol and a secondary alcohol.

    <p>A primary alcohol oxidizes to an aldehyde, which can further oxidize to a carboxylic acid, while a secondary alcohol oxidizes to a ketone.</p> Signup and view all the answers

    Why are tertiary alcohols resistant to oxidation?

    <p>Tertiary alcohols are resistant to oxidation because they lack a hydrogen atom attached to the carbon bearing the hydroxyl group, preventing oxidation.</p> Signup and view all the answers

    What unique characteristic of alcohols contributes to their weak acidity and basicity?

    <p>Alcohols possess a hydroxyl group (-OH) that can act as both a weak acid and a weak base, contributing to their unique acid-base properties.</p> Signup and view all the answers

    Why are amides considered neutral compared to amines?

    <p>Amides are neutral because their unbonded electron pair on the nitrogen atom is delocalized and cannot be donated.</p> Signup and view all the answers

    What are cyclic amides and how are they referred to?

    <p>Cyclic amides are called lactams.</p> Signup and view all the answers

    Explain the trend in base strength among primary, secondary, and tertiary amines.

    <p>The base strength trend is secondary &gt; tertiary &gt; primary due to the electron donating effects of alkyl groups.</p> Signup and view all the answers

    How do low molecular mass amines interact with water?

    <p>Low molecular mass amines can form hydrogen bonds with water, making them soluble.</p> Signup and view all the answers

    What is the primary consequence of hydrolysis reactions for amides during storage?

    <p>Hydrolysis reactions can occur if amides are not stored in a dry place, leading to the degradation of amides.</p> Signup and view all the answers

    Describe the physical state of amines with low molecular mass at room temperature.

    <p>Low molecular mass amines are gases at room temperature due to weak intermolecular attractions.</p> Signup and view all the answers

    What is the general structural formula of a primary amine?

    <p>The general structural formula of a primary amine is R-NH2.</p> Signup and view all the answers

    Why are amides resistant to oxidation under normal conditions?

    <p>Amides are resistant to oxidation because of the stability of their structure and lack of easily oxidizable functional groups.</p> Signup and view all the answers

    What is formed when an alcohol reacts with an acid?

    <p>An ester is formed when an alcohol reacts with an acid.</p> Signup and view all the answers

    Why are low molecular mass ethers soluble in water?

    <p>Low molecular mass ethers can form hydrogen bonds with water, making them soluble.</p> Signup and view all the answers

    What is the general formula for ethers?

    <p>The general formula for ethers is R-O-R.</p> Signup and view all the answers

    What is a significant concern regarding the storage of diethyl ether?

    <p>Peroxide formation in air is a significant concern when storing diethyl ether.</p> Signup and view all the answers

    What distinguishes aldehydes and ketones from alkenes in terms of bonding?

    <p>Aldehydes and ketones contain a polar carbonyl (C=O) bond, unlike the non-polar bonds in alkenes.</p> Signup and view all the answers

    What type of bonds do ethers form with each other?

    <p>Ethers form van der Waals bonds with each other.</p> Signup and view all the answers

    How does the presence of the carbonyl group impact the physical properties of aldehydes and ketones?

    <p>The polar carbonyl group leads to intermolecular attractions, making most aldehydes and ketones liquids at room temperature.</p> Signup and view all the answers

    What type of esters are biologically important, and why?

    <p>Phosphate esters are biologically important due to their role in energy transfer and metabolism.</p> Signup and view all the answers

    What is the primary advantage of supplying acidic drugs as salts?

    <p>The primary advantage is increased water solubility.</p> Signup and view all the answers

    What limits the solubility of higher molecular mass aldehydes and ketones in water?

    <p>They are less soluble due to their more 'alkane-like' properties and reduced capacity for hydrogen bonding.</p> Signup and view all the answers

    Why can aldehydes undergo oxidation while ketones cannot?

    <p>Aldehydes can be oxidized because they have a hydrogen atom attached to the carbonyl carbon, whereas ketones do not.</p> Signup and view all the answers

    What type of mechanism do carboxylic acids mainly undergo in reactions with nucleophiles?

    <p>Carboxylic acids mainly undergo nucleophilic substitution reactions.</p> Signup and view all the answers

    How do the boiling points of esters compare to those of amides, and why?

    <p>Esters have lower boiling points than amides due to the inability of esters to form hydrogen bonds.</p> Signup and view all the answers

    In the nucleophilic addition reaction of aldehydes, which atom does the nucleophile typically attack?

    <p>The nucleophile usually attacks the δ+ carbon atom of the carbonyl group.</p> Signup and view all the answers

    What type of reaction occurs when an amine acts as a nucleophile with aldehydes?

    <p>It results in the formation of a C=N bond, usually through the elimination of water.</p> Signup and view all the answers

    What is the reactivity trend of amides compared to esters?

    <p>Amides react much more slowly than esters.</p> Signup and view all the answers

    What is the main product of the reaction between an alcohol and a carboxylic acid?

    <p>The main product is an ester.</p> Signup and view all the answers

    How do low molecular mass aldehydes and ketones interact with water?

    <p>They can form hydrogen bonds with water, allowing for their solubility.</p> Signup and view all the answers

    What is the main product of the reduction reaction of aldehydes?

    <p>The reduction products of aldehydes are primarily primary alcohols.</p> Signup and view all the answers

    What role does hydrolysis play in the context of esters and amides?

    <p>Hydrolysis involves water acting as a nucleophile, breaking down esters and amides.</p> Signup and view all the answers

    Why are carboxylic acids more stable than aldehydes under normal storage conditions?

    <p>Carboxylic acids are less susceptible to oxidation than aldehydes.</p> Signup and view all the answers

    What role does protonation of the carbonyl oxygen play in aldehyde reactivity?

    <p>Protonation increases the electrophilicity of the carbonyl carbon, making it more reactive.</p> Signup and view all the answers

    How does the carbon chain length affect the water solubility of esters and amides?

    <p>Increasing carbon chain length decreases their solubility in water.</p> Signup and view all the answers

    In aqueous solutions, how do sugars form their cyclic structures involving aldehydes?

    <p>Sugars can react with their own carbonyl group, forming a hemiacetal through nucleophilic attack by the hydroxyl group.</p> Signup and view all the answers

    How do metal hydrides like LiAlH4 selectively reduce C=O groups but not C=C double bonds?

    <p>Metal hydrides selectively reduce C=O groups due to the strong nucleophilicity of hydride ions, which preferentially attacks the δ+ carbon atom of carbonyl compounds without affecting alkenes.</p> Signup and view all the answers

    What is the significance of the acyl group in carboxylic acids?

    <p>The acyl group, represented as R-C=O, is a defining part of carboxylic acids and is significant because it influences the acid's reactivity and properties.</p> Signup and view all the answers

    Explain why low molecular mass carboxylic acids are highly soluble in water.

    <p>Low molecular mass carboxylic acids are highly soluble in water due to their ability to form extensive hydrogen bonds with water molecules.</p> Signup and view all the answers

    What effect does an electron withdrawing group have on the strength of carboxylic acids?

    <p>An electron withdrawing group increases the strength of carboxylic acids by stabilizing the carboxylate ion formed upon proton donation.</p> Signup and view all the answers

    How does the presence of electron donating groups affect the acidity of carboxylic acids?

    <p>Electron donating groups decrease the acidity of carboxylic acids because they destabilize the carboxylate ion, making proton donation less favorable.</p> Signup and view all the answers

    What happens to aldehydes when they are exposed to air compared to ketones?

    <p>Aldehydes are unstable and oxidize in air to form carboxylic acids, while ketones generally do not oxidize under normal conditions.</p> Signup and view all the answers

    Describe the process of neutralizing a carboxylic acid using a base.

    <p>Neutralizing a carboxylic acid with a base, such as NaOH, involves the reaction between the acid and the base to form a salt and water.</p> Signup and view all the answers

    What determines the physical properties of carboxylic acids, such as their state at room temperature?

    <p>The physical properties of carboxylic acids, including their state at room temperature, depend on their relative molecular mass (RMM); acids with up to 9 carbon atoms are often liquids, while those with 10 or more tend to be solids.</p> Signup and view all the answers

    Study Notes

    Organic Functional Groups - Lecture 4

    • Alcohols:
      • General formula: R-OH
      • Physical properties: Form H-bonds between molecules, even low molar mass alcohols are liquids. H-bonds with water, so lower molar mass alcohols are very soluble in water. Longer chains result in decreased water solubility.
      • Weakly basic and weakly acidic.
      • Reversible protonation by strong acids.
      • Dissociate slightly in dilute aqueous solution by donating a proton to water.
      • Reactivity/Stability: Stable under normal conditions but reactive with other compounds, particularly mild oxidizing agents. Oxidation type depends on the alcohol's degree (1°, 2°, or 3°).
      • 1° alcohols oxidize to aldehydes, then to carboxylic acids.
      • 2° alcohols oxidize to ketones..
      • 3° alcohols are resistant to oxidation
      • Ester formation: Reaction with organic acids results in esters. Biologically, phosphate esters are important.

    Acidity Constants of Alcohols and Phenols

    • Specific examples of pKa values for various alcohols and phenols are provided. This table shows the increasing acidity from CH3CH2OH to 2,4,6-Trinitrophenol, with decreasing pKa values.

    Reactivity/Stability of Alcohols

    • Stable under normal conditions, but reactive towards other compounds.
    • Significant reaction with mild oxidizing agents. Oxidation type depends on 1°, 2°, or 3° alcohol.

    Ethers

    • General formula: R-O-R
    • Physical properties: Cannot form H-bonds amongst themselves, thus low RMM ethers are gases/liquids at room temperature. Can form H-bonds with water, so low RMM ethers are soluble in water. Solubility decreases with increasing chain length.
    • Reactivity/Stability: Relatively unreactive and are commonly used as solvents (e.g., diethyl ether). Like alkenes, they can form peroxides in air. Storing in an airtight container is recommended to avoid peroxide formation.

    Aldehydes and Ketones

    • Both contain a carbonyl (C=O) group.
      • Two R groups = ketone
      • At least one H = aldehyde
    • Physical properties: Polar C=O bond leads to intermolecular attractions but not H-bonds. Liquids at room temperature. Lower RMM compounds are water-soluble. Solubility decreases with increasing molecular mass.
    • Reactivity/stability: React with nucleophiles via nucleophilic addition reactions/Can be oxidized (aldehydes only).
    • When nucleophile is an alcohol, reaction products are hemiacetals (aldehydes) or hemiketals (ketones). These reactions are important in sugar chemistry.
    • Also important in drug-receptor combinations and enzyme reactions.

    Carboxylic Acids (Alkanoic Acids)

    • Formula: R-COOH
    • Physical properties: Long chains are solids at room temperature, while lower RMM are liquids. Considerable H-bonding results in high boiling points and solubility in water. Low RMM compounds are soluble in water, while higher RMM solubility decreases with increasing chain length.
    • Acidic nature: Donate protons (H+) to more basic substances (e.g., water). Carboxylate ion is stabilized by resonance.
    • Relative strength: Depends on R groups. Electron-withdrawing groups increase acid strength, while electron-donating groups decrease it..

    Salt Formation

    • An acid can be neutralized by reacting with a base (e.g., NaOH) to form a salt.
    • This process can significantly increase the water solubility of insoluble carboxylic acids, which is practically useful in medicine.

    Reactivity of Carboxylic Acids

    • Reactions involving acyl (R-C=O) groups are usually nucleophilic substitutions.
    • When reacting with an alcohol, the resulting product is an ester.

    Oxidation of Carboxylic Acids

    • Under normal conditions, carboxylic acids are resistant to oxidation. They are significantly more stable to oxidation than aldehydes.

    Esters and Amides

    • General Structure
      • Ester: R-C(=O)-O-R'
      • Amide: R-C(=O)-N-R1R2
    • Esters and amides have different boiling points and water solubility.
    • Amides:
      • Can form hydrogen bonds, allowing higher boiling points than esters.
      • Generally, less reactive than esters, with significant reactions involving nucleophilic substitutions when acting as the carboxylic acid derivative group.

    Amines

    • General Structure: R-NH2 (primary), R-NHR (secondary), R-NR2 (tertiary).
    • Properties:
      • Lower molar mass amines are gases at room temperature
      • Higher molar mass amines tend to be liquids
      • Low RMM amines are soluble in water, solubility decreases with increasing chain length (becomes more "alkane-like")
    • Amines as Bases:
      • Take up protons from acid due to the pair of electrons on the N atom.
      • Relative base strength differs in the 1°, 2°, and 3° amines. Steric hindrance can affect the strength.

    Storage Considerations

    • Aldehydes and ketones require storage in a cool dry location

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    Organic Functional Groups Lecture 4 PDF

    Description

    This quiz covers the properties and reactions of alcohols, including their general formula, physical properties, and reactivity with other compounds. Key concepts such as acidity constants, protonation, and the formation of esters are also explored. Test your knowledge of these fundamental aspects of organic chemistry!

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