Warning: foreach() argument must be of type array|object, bool given in /var/www/html/web/app/themes/studypress-core-theme/template-parts/header/mobile-offcanvas.php on line 20

The following hydrocarbon has an unusually large dipole moment. Explain how a large dipole moment might arise

(a)Cyclopnonatetraene cation

(b) Cyclononatetraene anion

(c) [16] annulene dianion

(d) [18] annulene dianion

(e)

(f) [20] annulene dication

Short Answer

Expert verified

(a)

(b)

(c)

(d)

(e)

(f) [20] annulene dication

Step by step solution

01

Criteria for aromatic and antiaromatic compounds

The aromatic compounds are those that meet the following criteria:

  1. The structure must be cyclic have a continuous ring of overlapping p orbitals, usually in a planar conformation.
  2. Delocalization of the pi electrons over the ring must lower the electronic energy.
  3. It should have (4n+2) pi electrons, where n is an integer.

The antiaromatic compounds are those that meet the following criteria:

  1. The structure must be cyclic have a continuous ring of overlapping p orbitals, usually in a planar conformation.
  2. Delocalization of the pi-electron over the ring must lower the electronic energy.
  3. It should have 4n pi electrons, where n is an integer.

A cyclic compound that does not have a continuous, overlapping of p orbitals cannot be aromatic or antiaromatic. It is said to be nonaromatic or aliphatic

02

Classification of the aromatic, antiaromatic and nonaromatic molecule

(a) Cyclononatetraene cation is cyclic having continuous overlapping of p orbitals and it has 4n pi electrons. Hence, it is antiaromatic.

(b) Cyclononatetraene anion is cyclic having continuous overlapping of p orbital and it has 4n+2 pi electrons. Hence, it is aromatic.

(c) [16] annulene dianion is cyclic having continuous overlapping of p orbital and it has 4n+2 pi electrons. Hence, it is aromatic.

(d) [18] annulene dianion is cyclic having continuous overlapping of p orbital and it has 4n pi electrons. Hence, it is antiaromatic.

(e) The given compound is cyclic but does not have a continuous, overlapping ring of p orbitals. Hence, it is non aromatic.

(f) [20] annulene dication is cyclic having continuous overlapping of p orbital and it has 4n+2 pi electrons. Hence, it is aromatic.

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 Vaia!

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

Question: The benzene ring alters the reactivity of a neighboring group in the benzylic position much as a double bond alters the reactivity of groups in the allylic position.

Benzylic cations, anions, and radicals are all more stable than simple alkyl intermediates.

  1. Use resonance forms to show the delocalization (over four carbon atoms) of the positive charge, unpaired electron, and negative charge of the benzyl cation, radical, and anion.
  2. Toulene reacts with bromine in the presence of light to give benzyl bromide. Propose a mechanism for this reaction.

c. Which of the following reactions will have the faster rate and give the better yield? Use a drawing of the transition state to explain your answer.

Borazole, ,is an unusually stable cyclic compound. Propose a structure for borazole, and explain why it is aromatic.

Show which of the nitrogen atoms in purine are basic, and which one is not basic. For the nonbasic nitrogen, explain why its nonbonding electrons are not easily available to become protonated

Question: For each NMR spectrum, propose a structure consistent with the spectrum and the additional information provided.

a. Elemental analysis shows the molecular formula to be C8H7OCl . The IR spectrum shows a moderate absorption at 1602 cm-1 and a strong absorption at 1690 cm-1 .

b.The mass spectrum shows a double molecular ion of ratio 1:1 at m/z 184 and 186.

Question: The benzene ring alters the reactivity of a neighboring group in the benzylic position much as a double bond alters the reactivity of groups in the allylic position.

Benzylic cations, anions, and radicals are all more stable than simple alkyl intermediates.

  1. Use resonance forms to show the delocalization (over four carbon atoms) of the positive charge, unpaired electron, and negative charge of the benzyl cation, radical, and anion.
  2. Toulene reacts with bromine in the presence of light to give benzyl bromide. Propose a mechanism for this reaction.

    c. Which of the following reactions will have the faster rate and give the better yield? Use a drawing of the transition state to explain your answer.

See all solutions

Recommended explanations on Chemistry Textbooks

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.

Sign-up for free