Textbook Question
Provide a mechanism for the formation of the hemiacetals shown. [Only (c) is favored as written.]
(a)
1171
views
Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
All textbooks
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 31c
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 31cChapter 16, Problem 31c
Identify the hemiacetal functional group in each of the following molecules. These molecules may not be stable enough to be the favorable product in an equilibrium reaction.
(c) 
Verified step by step guidance1
Understand the structure of a hemiacetal: A hemiacetal is formed when an alcohol adds to an aldehyde or ketone. It contains a carbon atom bonded to an -OH group, an -OR group, a hydrogen atom (in the case of aldehydes), and an alkyl or aryl group.
Examine the given molecule structure in the image. Look for a carbon atom that is bonded to both an -OH group and an -OR group. This is the key feature of a hemiacetal.
Check the connectivity of the carbon atom: Ensure that the carbon atom with the -OH and -OR groups is also bonded to either a hydrogen atom (if derived from an aldehyde) or another carbon atom (if derived from a ketone).
Verify the presence of the hemiacetal group: Confirm that the identified carbon atom does not have any additional substituents that would disqualify it from being a hemiacetal.
Once the hemiacetal group is identified, consider the stability of the molecule. Note that hemiacetals are often unstable and may not be the predominant form in equilibrium, but the task is to identify the functional group, not to assess stability.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hemiacetal Structure
A hemiacetal is formed when an aldehyde or ketone reacts with an alcohol, resulting in a carbon atom bonded to both a hydroxyl group (-OH) and an alkoxy group (-OR). This functional group is characterized by the presence of one -OH and one -OR group attached to the same carbon, which is typically derived from the carbonyl carbon of the original aldehyde or ketone.
Recommended video:
Guided course
06:23
Monosaccharides - Forming Cyclic Hemiacetals
Equilibrium in Organic Reactions
In organic chemistry, equilibrium refers to the state where the rate of the forward reaction equals the rate of the reverse reaction, leading to constant concentrations of reactants and products. Understanding equilibrium is crucial for predicting the stability of hemiacetals, as they may not be the favored product in a reaction, especially if the equilibrium lies towards the reactants.
Recommended video:
Guided course
04:00Determining Acid/Base Equilibrium
Stability of Hemiacetals
Hemiacetals are often less stable than their corresponding acetals, which are formed when a hemiacetal reacts with another alcohol. The stability of a hemiacetal can be influenced by steric factors, electronic effects, and the nature of the substituents on the carbon atom. In many cases, hemiacetals exist in equilibrium with their parent carbonyl compounds, making them transient species in organic reactions.
Recommended video:
Guided course
06:23Monosaccharides - Forming Cyclic Hemiacetals
Related Practice
Textbook Question
Suggest a carbonyl to react with NaCN/HCN to produce the following cyanohydrins.
(a)
984
views
Textbook Question
Show the product expected by the Wolff–Kishner reduction of the following aldehydes/ketones.
(a)
957
views
Textbook Question
Suggest the appropriate carbonyl and Wittig reagent to make the following alkenes.
a. (E)-7-methylnon-4-en-3-one
760
views
Textbook Question
Which of the following cyclic hemiacetals would you expect to have the highest Keq for their formation? Explain your answer.
(a)
934
views
Textbook Question
For each of the following carbonyl addition reactions, would you expect a racemic mixture or a mixture enriched in one stereoisomer? In each case, draw both possible stereoisomeric products.
(a)
857
views