A mechanism to account for the given reaction, which scrambles the isotopic labeling, is to be drawn. Concept introduction: The Diels–Alder reaction joins a conjugated diene and a dienophile (either an alkene or an alkyne ) via the formation of two new σ bonds. The product is a six-membered ring of carbon atoms. The Diels–Alder reaction is concerted that is all bonds that are formed and broken do so simultaneously. It requires the cyclic movement of electrons, so it is classified as a pericyclic reaction. Under normal conditions, Diels–Alder reactions tend to be irreversible and proceed under kinetic control. At high temperatures, though, some can undergo the reverse reaction — This is called as a retro Diels–Alder reaction or [ 4 + 2 ] cyclo elimination. The mechanism for this reaction is simply the reverse of a Diels–Alder mechanism, so the entire reaction consists of a single (concerted) step in which six electrons move in a cyclic fashion.

Question

Want to see the full answer?

Answer 1

Question

Chapter 24, Problem 24.53P

Interpretation Introduction

Interpretation:

A mechanism to account for the given reaction, which scrambles the isotopic labeling, is to be drawn.

Concept introduction:

The Diels–Alder reaction joins a conjugated diene and a dienophile (either an alkene or an alkyne) via the formation of two new σ bonds. The product is a six-membered ring of carbon atoms. The Diels–Alder reaction is concerted that is all bonds that are formed and broken do so simultaneously. It requires the cyclic movement of electrons, so it is classified as a pericyclic reaction. Under normal conditions, Diels–Alder reactions tend to be irreversible and proceed under kinetic control. At high temperatures, though, some can undergo the reverse reaction — This is called as a retro Diels–Alder reaction or [4 + 2] cyclo elimination. The mechanism for this reaction is simply the reverse of a Diels–Alder mechanism, so the entire reaction consists of a single (concerted) step in which six electrons move in a cyclic fashion.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Students have asked these similar questions

Assign this HSQC Spectrum ( please editing clearly on the image)

(a 4 shows scanning electron microscope (SEM) images of extruded actions of packing bed for two capillary columns of different diameters, al 750 (bottom image) and b) 30-μm-i.d. Both columns are packed with the same stationary phase, spherical particles with 1-um diameter. A) When the columns were prepared, the figure shows that the column with the larger diameter has more packing irregularities. Explain this observation. B) Predict what affect this should have on band broadening and discuss your prediction using the van Deemter terms. C) Does this figure support your explanations in application question 33? Explain why or why not and make any changes in your answers in light of this figure. Figure 4 SEM images of sections of packed columns for a) 750 and b) 30-um-i.d. capillary columns.³

fcrip = ↓ bandwidth Il temp 32. What impact (increase, decrease, or no change) does each of the following conditions have on the individual components of the van Deemter equation and consequently, band broadening? Increase temperature Longer column Using a gas mobile phase instead of liquid Smaller particle stationary phase Multiple Paths Diffusion Mass Transfer