Textbook Question
Rationalize the ranking of increasing reaction rate of the benzylic halides shown.
285
views
Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring
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. 24 - Benzene II: Reactions Influenced by the Aromatic RingProblem 51
Mullins 1st EditionCh. 24 - Benzene II: Reactions Influenced by the Aromatic RingProblem 51Chapter 23, Problem 51
Rationalize the fact that 1,4-dihydroxybenzene melts at a significantly higher temperature than 1,2-diydroxybenzene.
Verified step by step guidance1
Identify the two compounds: 1,4-dihydroxybenzene (para-dihydroxybenzene) and 1,2-dihydroxybenzene (ortho-dihydroxybenzene). Note their melting points: 172°C for 1,4-dihydroxybenzene and 105°C for 1,2-dihydroxybenzene.
Consider the molecular structure of each compound. In 1,4-dihydroxybenzene, the hydroxyl groups are positioned opposite each other on the benzene ring, while in 1,2-dihydroxybenzene, the hydroxyl groups are adjacent.
Analyze the potential for hydrogen bonding. In 1,4-dihydroxybenzene, the hydroxyl groups can form intermolecular hydrogen bonds with other molecules, leading to a more stable and tightly packed crystal lattice.
In contrast, 1,2-dihydroxybenzene can form intramolecular hydrogen bonds between the adjacent hydroxyl groups, which reduces the ability to form strong intermolecular hydrogen bonds, resulting in a less stable crystal lattice.
Conclude that the stronger intermolecular hydrogen bonding in 1,4-dihydroxybenzene leads to a higher melting point compared to 1,2-dihydroxybenzene, where intramolecular hydrogen bonding predominates.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrogen Bonding
Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when a hydrogen atom covalently bonded to a highly electronegative atom, like oxygen, interacts with another electronegative atom. In the case of 1,4-dihydroxybenzene, the hydroxyl groups are positioned para to each other, allowing for effective hydrogen bonding between molecules, which significantly increases the melting point.
Recommended video:
Guided course
00:48
The definition of hydrogenation.
Molecular Structure and Isomerism
Molecular structure refers to the arrangement of atoms within a molecule, which can greatly influence its physical properties. 1,4-Dihydroxybenzene (para) has a symmetrical structure that facilitates stronger intermolecular interactions compared to 1,2-dihydroxybenzene (ortho), where steric hindrance can disrupt effective packing and bonding, leading to a lower melting point.
Recommended video:
Guided course
06:47Monosaccharides - D and L Isomerism
Melting Point and Intermolecular Forces
The melting point of a substance is the temperature at which it transitions from solid to liquid, heavily influenced by the strength of intermolecular forces. Stronger intermolecular forces, such as hydrogen bonds in 1,4-dihydroxybenzene, result in a higher melting point compared to weaker forces in 1,2-dihydroxybenzene, which experiences more steric hindrance and less effective packing.
Recommended video:
Guided course
03:08How IMFs are related to melting and boiling points.
Related Practice
Textbook Question
The following steps were used in the synthesis of the antimalarial thiaplakortone A. Identify the missing reagents, (a) and (b),
982
views
Textbook Question
A chemist attempted to oxidize a primary alcohol to a carboxylic acid using chromic acid. The product shown was obtained as a major component in the mixture. Suggest an arrow-pushing mechanism that accounts for its formation. [Think about what chromic acid would normally do to a phenol and make a list of bonds formed and bonds broken.]
1188
views
Textbook Question
Identify the aromatic product that would result from the oxidation of the triol with an excess of PCC.
575
views
Textbook Question
In Chapter 23, we learned about the electrophilic aromatic nitration reaction. When phenol is subjected to these conditions with a large excess of nitric acid, a molecule called picric acid is produced. Predict the product of this reaction and explain why the pKa value of this compound is 0.38.
1042
views
Textbook Question
The following reaction proceeds in good yield, despite requiring high temperature and high concentration. Identify the product you’d expect to obtain in this reaction.
514
views