Concept explainers
Interpretation:
Electron delocalization in cyclooctatetraene based on the location of signal in
Concept introduction:
Nuclear Magnetic Resonance (NMR) is one of the most capable analytical techniques used for determining the functional groups and how the atoms are structured and arranged in a molecule.
Few elements, such as
In
Induced magnetic field consists of electricity generated from movement in a magnetic field.
The position of a signal on x-axis in the
The number of signals in
The area covered by the signal is proportional to the number of equivalent protons causing the signal.
The hydrogen atoms on adjacent carbon atoms split the signal into two or more peaks. One, two or three hydrogen atoms split the signal into two, three or four peaks described as doublet, triplet or quartet respectively.
A decrease in the electron density around a proton deshields the signal downfield at a larger value of chemical shift.
An increase in electron density shields the signal upfield at a lower value of chemical shift.
The number of signals in NMR spectra shows the number of different chemical environments in a molecule.
Aromatic protons give signal downfield between
Alkene protons give signal upfield between
Want to see the full answer?
Check out a sample textbook solutionChapter 14 Solutions
EBK ORGANIC CHEMISTRY
- Azulene, an isomer of naphthalene, has a remarkably large dipole moment for a hydrocarbon (µ = 1.0 D). Explain using resonance structures.arrow_forwardA compound has the molecular formula C6H12O2. Its IR spectrum shows a strong absorption band near 1740 cm-1. Its 1H NMR spectrum consists of two singlets at δ 1.2 and δ 3.6. Which is the most likely structure of the compound?arrow_forwardA chemist isolated an aromatic compound with molecular formula C6H4Br2. He treated this compound with nitric acid and sulfuric acid and isolated threedifferent isomers, in different amounts, with molecular formula C6H3Br2NO2. What was the structure of the original compound?arrow_forward
- Acridine is a heterocyclic aromatic compound obtained from coal tar that is used in the synthesis of dyes. The molecular formula of acridine is C13H9N, and its ring system is analogous to that of anthracene except that one CH group has been replaced by N. The two most stable resonance structures of acridine are equivalent to each other, and both contain a pyridine-like structural unit. Write a structural formula for acridine.arrow_forwardDescribe the ground-state electron configuration of the cyclopentadienyl cation and radical. Assuming each species is planar, would you expect it to be aromatic or antiaromatic?arrow_forwardCompound A exhibits a peak in its 1H NMR spectrum at 7.6 ppm, indicating that it is aromatic. (a) How are the carbon atoms of the triple bonds hybridized? (b) In what type of orbitals are the π electrons of the triple bonds contained? (c) How many π electrons are delocalized around the ring in A?arrow_forward
- 1,3,5,7-Cyclooctatetraene, CgHg, is an unusual hydrocarbon in that it reacts with exactly 2 equivalents of potassium to give A, CgHgK₂, which can be isolated as a white solid. A exhibits a single proton NMR signal. Draw the structure of A. 1,3,5,7-cycloctatetraene 2 K/THF C8H8K2 + H₂ A • Draw cations and anions in separate sketchers. Separate structures with + signs from the drop-down menu. ? n ChemDoodle®arrow_forwardCompound X, C,4H12Br2, is optically inactive. On treatment with strong base, X gives hydrocarbon Y, C14H10: Compound Y absorbs 2 equivalents of hydrogen when reduced over a palladium catalyst to give z (C14H14) and reacts with ozone to give one product, benzoic acid (C,Hg02). Draw the structure of compound Z. • Use the wedge/hash bond tools to indicate stereochemistry where it exists. • Ignore alkene stereochemistry. • If more than one structure fits the description, draw them all. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. • Separate structures with + signs from the drop-down menu. ChemDoodlearrow_forwardOne of the four criteria of aromaticity by Hückel is planarity of the rings containing 4n+2 electrons. Based on the Hückel rules, can a compound be aromatic but not planar? Please explain your answer.arrow_forward
- How many rings and π(pi) bonds are contained in compound A and draw one possible structure for this compound A. Compound A has molecular formula C6H10 and is hydrogenated to a compound having molecular formula C6H12arrow_forwardGive reasons: (i) C—Cl bond length in chlorobenzene is shorter than C—Cl bond length in CH3—Cl.(ii) The dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.(iii) SN1 reactions are accompanied by racemization in optically active alkyl halidesarrow_forwardDescribe the ground-state electron configuration of the cycloheptatrienyl radical and anion. Assuming each species is planar, would you expect them to be aromatic or antiaromatic?arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning