30. There is another approach to predicting the stereochemistry of electrocyclic ring closures. One simply looks at the ends of the HOMO to conclude the proper direction for rotation of the bond by creating in-phase interactions during closure. Show that this method also predicts conrotatory closure for butadiene and disrotatory closure for hexatriene. 31. Predict the thermally allowed products of the following two mraction
Analyzing Infrared Spectra
The electromagnetic radiation or frequency is classified into radio-waves, micro-waves, infrared, visible, ultraviolet, X-rays and gamma rays. The infrared spectra emission refers to the portion between the visible and the microwave areas of electromagnetic spectrum. This spectral area is usually divided into three parts, near infrared (14,290 – 4000 cm-1), mid infrared (4000 – 400 cm-1), and far infrared (700 – 200 cm-1), respectively. The number set is the number of the wave (cm-1).
IR Spectrum Of Cyclohexanone
It is the analysis of the structure of cyclohexaone using IR data interpretation.
IR Spectrum Of Anisole
Interpretation of anisole using IR spectrum obtained from IR analysis.
IR Spectroscopy
Infrared (IR) or vibrational spectroscopy is a method used for analyzing the particle's vibratory transformations. This is one of the very popular spectroscopic approaches employed by inorganic as well as organic laboratories because it is helpful in evaluating and distinguishing the frameworks of the molecules. The infra-red spectroscopy process or procedure is carried out using a tool called an infrared spectrometer to obtain an infrared spectral (or spectrophotometer).
![30. There is another approach to predicting the stereochemistry of electrocyclic ring closures. One simply looks at the ends
of the HOMO to conclude the proper direction for rotation of the bond by creating in-phase interactions during closure.
Show that this method also predicts conrotatory closure for butadiene and disrotatory closure for hexatriene.
31. Predict the thermally allowed products of the following two reactions.
2 D
O
32. The following reaction is known as the Carroll rearrangement. Write a mechanism for this reaction. What pericyclic
reactions involved?
RR
H
Base
Heal
O
33. At first glance, the following reaction appears to be a [2 + 2] cycloaddition of a single double bond from cyclopentadiene
with the C=C double bond of diphenylketene. However, it has been experimentally shown that the product actually
results from two more conventional pericyclic reactions. Show by writing an alternative mechanism what these two
reactions must be.
I
Ph
Ph
Ph
Ph-
CO₂
O
34. The retroene reaction is, as the name implies, the reverse of an ene reaction. Show how the following reaction conforms to
this name. Explain the cis stereochemistry in the product.
A
35. A rare, but sometimes observed, class of pericyclic reactions is called atom transfer or group transfer reactions. A single
example is given below, where two hydrogens are transferred to an alkene in a concerted single-step reaction. Using ethyl-
ene and ethane as models for the alkene and alkane portion of this reaction, draw an orbital correlation diagram for this
reaction. Is it allowed or forbidden? Similarly, analyze the reaction using an FMO approach, and lastly examine aromatic
transition state theory and the generalized pericyclic selection rule.
Ring-opening
36. Figure 15.9 defined suprafacial and antarafacial interactions of a lone pair in ap orbital (called an o component).
Using these definitions, predict if the ring-opening of the cyclopropyl anion shown below will occur in a conrotatory
or disrotatory fashion. What will be the stereochemistry of the product?
arrow pushing shows a cvelic](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff6f016a3-2e93-4eed-9c9f-5e860e172a66%2F709ae8e8-d521-47f1-bd73-f3cde4d73a9a%2Fawvnzua_processed.jpeg&w=3840&q=75)
Step by step
Solved in 5 steps with 5 images
