/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 33 From among the isomeric compound... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 14: Problem 33

From among the isomeric compounds of molecular formula \(\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{Cl}\), choose the one having a \({ }^{1}\) H NMR spectrum that (a) Contains only a single peak (b) Has several peaks including a doublet at \(83.4\) (c) Has several peaks including a triplet at \(\delta 3.5\) (d) Has several peaks including two distinct three-proton signals, one of them a triplet at \(\delta 1.0\) and the other a doublet at \(\delta 1.5\)

Short Answer

Expert verified
(a) tert-butyl chloride; (b) dependent on specific conditions; (c) butyl chloride; (d) 2-chlorobutane.

Step by step solution

01

Understanding the Molecular Formula

The molecular formula \( \mathrm{C}_{4} \mathrm{H}_{9} \mathrm{Cl} \) can represent several isomers since there are various ways to arrange carbon, hydrogen, and chlorine atoms. Isomers mean these molecules have the same molecular formula but different structural arrangements.
02

Analyzing Criterion (a) - Single Peak

A compound with only a single peak in \(^1\)H NMR indicates that all hydrogen atoms are in an equivalent environment. This arrangement is possible in a symmetrical structure like \( \mathrm{C} (\mathrm{Cl})(\mathrm{CH}_3)(\mathrm{CH}_3)(\mathrm{CH}_3) \), known as tert-butyl chloride. Here, all 9 hydrogen atoms are equivalent as they exist in three identical methyl groups.
03

Analyzing Criterion (b) - Doublet at 83.4

For a doublet to appear, one set of protons is split by an adjacent proton (\(n+1\) rule where \(n\) is the number of neighboring protons). The compound is likely \( \mathrm{ClCH}_2\mathrm{CH}_2\mathrm{CH}_2\mathrm{CH}_3 \). The protons near the chlorine (\(\mathrm{Cl}-\mathrm{CH}_2\) group) can create this doublet, as the chlorine atom causes a larger chemical shift. However, based on the values provided, this might involve a rare, specific isotope or consideration beyond standard cases at 83.4 ppm.
04

Analyzing Criterion (c) - Triplet at 未 3.5

The presence of a triplet suggests a proton is coupled to two equivalent protons (\(n+1\) rule). The compound that fits is likely \( \mathrm{ClCH}_2\mathrm{CH}_2\mathrm{CH}_3 \). The \(\mathrm{CH}_2\) protons adjacent to \(\mathrm{CH}_3\) and \(\mathrm{Cl}-\mathrm{CH}_2\) group will show a triplet due to coupling by the two \(\mathrm{CH}_2\) protons at \(\delta 3.5\).
05

Analyzing Criterion (d) - Two Three-Proton Signals

In the compound \( \mathrm{ClCH}_2\mathrm{CH}(\mathrm{CH}_3)\mathrm{CH}_3 \), the triplet at \(\delta 1.0\) corresponds to the methyl group \(\mathrm{CH}_3\) adjacent to the \(\mathrm{CH}_2\) group. The doublet at \(\delta 1.5\) is due to a methyl group \(\mathrm{CH}_3\) adjacent to a methine proton (\(\mathrm{CH}\)). This structure allows coupling causing a triplet and a doublet for two different methyl groups.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Isomerism
Isomerism is a fascinating concept in chemistry that describes compounds with the same molecular formula but different structural arrangements. These structural differences can affect the physical and chemical properties of the compounds, even though they consist of the same elements in the same proportions. There are several types of isomerism, but for
  • Structural Isomers: These have the same molecular formula but differ in the connectivity of their atoms.
  • Stereoisomers: These have the same molecular formula and atom connectivity but differ in the spatial arrangement of atoms.
In the case of the molecular formula \(\mathrm{C}_{4}\mathrm{H}_{9}\mathrm{Cl}\), each isomer can have unique properties and behave differently in an NMR spectrum.
Understanding isomerism can aid in predicting and explaining these behaviors, making it a crucial concept in molecular chemistry.
Molecular Formula
The molecular formula represents the count of each type of atom in a molecule. For example, \(\mathrm{C}_{4}\mathrm{H}_{9}\mathrm{Cl}\) indicates a molecule composed of four carbon atoms, nine hydrogen atoms, and one chlorine atom. However, while the molecular formula provides a snapshot of the molecule's composition, it doesn't detail its structure.
  • Molecular Formula vs. Structural Formula: A structural formula shows how the atoms are connected, revealing potential isomers.
  • Significance in NMR: The molecular formula alone doesn't provide enough information for predicting NMR spectra unless the molecule's structure is known.
When solving problems related to NMR, knowing the molecular formula helps narrow down possible isomers, which helps in predicting how it will appear on an NMR spectrum.
Proton Coupling
Proton coupling in NMR spectroscopy occurs due to the interaction between non-equivalent neighboring protons. This interaction is explained by the \(n+1\) rule, which states that a set of equivalent protons will split into \(n+1\) peaks, where \(n\) is the number of neighboring, non-equivalent protons.
  • Doublets and Triplets: A doublet results when a proton has one neighboring proton (\(n=1\)), while a triplet appears when a proton is coupled to two (\(n=2\)) neighboring protons.
Proton coupling adds another layer of complexity to analyzing NMR spectra, as it provides detailed information about the molecule's structure and the spatial arrangement of different atoms. Understanding how proton coupling functions allow chemists to infer much information from an NMR spectrum about the proximity of different hydrogen atoms.
Chemical Shifts
In NMR spectroscopy, chemical shifts provide information about the electronic environment of nuclei within a molecule. This is expressed on the \(\delta\) scale, measured in parts per million (ppm).
  • Factors Affecting Chemical Shifts: Electronegativity, nearby functional groups, and electron density can all impact the position of a chemical shift. For instance, an electronegative atom like chlorine can cause a downfield shift (move to a higher \(\delta\) value), due to its high electron-withdrawing capability.
  • Predicting NMR Responses: Recognizing expected chemical shift regions enables the prediction of proton environments, helping identify specific hydrogen locations within a molecule.
Chemical shifts are instrumental in interpreting NMR data, as they give clues about molecular environments and help piece together structural information, by hinting at how atoms are grouped and bonded together in a molecule.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A compound \(\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{ClO}_{2}\right)\) exhibited three peaks in its \({ }^{13} \mathrm{C}\) NMR spectrum at \(\delta 46.8\left(\mathrm{CH}_{2}\right), 863.5\left(\mathrm{CH}_{2}\right)\), and \(\delta 72.0(\mathrm{CH})\). Excluding compounds that have \(\mathrm{Cl}\) and \(\mathrm{OH}\) on the same carbon, which are unstable, what is the most reasonable structure for this compound?

Which one of the following statements incorrectly describes the expected coupling of the proton at \(\mathrm{C}-1\) in the stereoisomeric 4 -tert- butylcyclohexanols? In the trans isomer the coupling constant between: (a) the proton at \(\mathrm{C}(1)\) and the axial protons at \(\mathrm{C}(2)\) and \(\mathrm{C}(6)\) is \(8 \mathrm{~Hz}\). (b) the proton at \(\mathrm{C}(1)\) and the equatorial protons at \(\mathrm{C}(2)\) and \(\mathrm{C}(6)\) is \(2 \mathrm{~Hz}\). In the cis isomer the coupling constant between: (c) the proton at \(\mathrm{C}(1)\) and the axial protons at \(\mathrm{C}(2)\) and \(\mathrm{C}(6)\) is \(8 \mathrm{~Hz}\). (d) the proton at \(\mathrm{C}(1)\) and the equatorial protons at \(\mathrm{C}(2)\) and \(\mathrm{C}(6)\) is \(2 \mathrm{~Hz}\).

Which would you expect to be more shielded, the carbonyl carbon of an aldehyde or a ketone? Why?

\(\lambda_{\max }\) for the \(\pi \rightarrow \pi^{*}\) transition in ethylene is \(170 \mathrm{~nm}\). Is the HOMO-LUMO energy difference in ethylene greater than or less than that of cis,trans-1,3-cyclooctadiene ( \(230 \mathrm{~nm}\) )?

Describe the appearance of the 'H NMR spectrum of each of the following compounds. How many signals would you expect to find, and into how many peaks will each signal be split? (a) 1,2 -Dichloroethane (d) \(1,2,2\) -Trichloropropane (b) \(1,1,1\) -Trichloroethane (e) \(1,1,1,2\) -Tetrachloropropane (c) \(1,1,2\) - Trichloroethane
See all solutions

Recommended explanations on Chemistry Textbooks

Nuclear Chemistry

Read Explanation

Kinetics

Read Explanation

Chemical Analysis

Read Explanation

Inorganic Chemistry

Read Explanation

Chemistry Branches

Read Explanation

The Earths Atmosphere

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.