(a)
Interpretation:
It should be identified that will a thermal 1, 3-migrations of carbon occur with whether retention or inversion of configuration.
Concept introduction:
Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”. There is a single transition state from start to finish, in contrast to a stepwise reaction.
There are mainly three types of pericyclic reactions,
- 1) Electrocyclic reactions
- 2) Cycloaddition reactions
- 3) Sigmatropic reactions
In a sigmatropic reaction “ one new sigma-bond is formed as another breaks.”
Sigmatropic rearrangement reactions are named with digits. For example a [1, 3] sigmatropic rearrangement describe a reaction in which the residue migrates from position 1 to position 3.
Migration of carbon and hydrogen will occur in a sigmatropic rearrangement reaction.
When hydrogen migrates in a sigmatropic rearrangement, the s orbital of the hydrogen is partially bonded to both the migration origin and the migration terminus in the transition state.
Migration of hydrogen in suprafacial and antarafacial rearrangement can be represented as follows,
Migration of carbon occurs through two ways because it has a two lobed p orbital. Carbon can simultaneously interact with the migration origin and the migration terminus using one lobe of its p orbital.
Migration of carbon in suprafacial and antarafacial rearrangement can be represented as follows,
Carbon migrating with one lobe of its p orbital interacting
Carbon migrating with both lobe of its p orbital interacting
Inversion of configuration is the inversion of a chiral center in a molecule in a
Retention of configuration is the preservation of integrity of the spatial arrangement of bonds to a chiral center during a chemical reaction.
(b)
Interpretation:
It should be identified that will a thermal 1, 5-migrations of carbon occur with whether retention or inversion of configuration.
Concept introduction:
Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”. There is a single transition state from start to finish, in contrast to a stepwise reaction.
There are mainly three types of pericyclic reactions,
- 1) Electrocyclic reactions
- 2) Cycloaddition reactions
- 3) Sigmatropic reactions
In a sigmatropic reaction “ one new sigma-bond is formed as another breaks.”
Sigmatropic rearrangement reactions are named with digits. For example a [1, 3] sigmatropic rearrangement describe a reaction in which the residue migrates from position 1 to position 3.
Migration of carbon and hydrogen will occur in a sigmatropic rearrangement reaction.
When hydrogen migrates in a sigmatropic rearrangement, the s orbital of the hydrogen is partially bonded to both the migration origin and the migration terminus in the transition state.
Migration of hydrogen in suprafacial and antarafacial rearrangement can be represented as follows,
Migration of carbon occurs through two ways because it has a two lobed p orbital. Carbon can simultaneously interact with the migration origin and the migration terminus using one lobe of its p orbital.
Migration of carbon in suprafacial and antarafacial rearrangement can be represented as follows,
Carbon migrating with one lobe of its p orbital interacting
Carbon migrating with both lobe of its p orbital interacting
Inversion of configuration is the inversion of a chiral center in a molecule in a chemical reaction.
Retention of configuration is the preservation of integrity of the spatial arrangement of bonds to a chiral center during a chemical reaction.
Want to see the full answer?
Check out a sample textbook solutionChapter 28 Solutions
EBK ORGANIC CHEMISTRY
- e. If (3R,4R)-3,4-dichloro-2,5-dimethylhexane and (3R,4S)-3,4-dichloro-2,5-dimethylhexane are in a solution at the same concentration, would this solution be expected to rotate plane polarized light (that is, be optically active)? Please provide your reasoning for your answer. [If you read this problem carefully, you will not need to draw out the structures to arrive at your answer...]arrow_forward1. How many neighbors does the proton that produces the multiplet below have? 2. 3. اللـ Draw a partial structure from the multiplet below. (The integration of the multiplet is 6) M Using the additivity constants found in appendix G of your lab manual, calculate the approximate chemical shifts of the protons indicated below. (Show your work!!!) B A Br SHarrow_forward1) Suppose 0.1 kg ice at 0°C (273K) is in 0.5kg water at 20°C (293K). What is the change in entropy of the ice as it melts at 0°? To produce the original "water gas" mixture, carbon (in a combustible form known as coke) is reacted with steam: 131.4 kJ + H20(g) + C(s) → CO(g) + H2(g) From this information and the equations in the previous problem, calculate the enthalpy for the combustion or carbon to form carbon dioxide. kindly show me how to solve this long problem. Thanksarrow_forward
- 4. An 'H-NMR of a compound is acquired. The integration for signal A is 5692 and the integration for signal B is 25614. What is the simplest whole number ratio of protons for signals A and B? (Show your work!!!) 5. Assign the carbons in the NMR below as either carbonyl, aromatic, or alkyl. 200 150 100 50 ō (ppm) 1arrow_forwardSpeaking of composite materials, indicate the correct option:(A). Composite materials can only be: metal-polymer or polymer-polymer.(B). Composite materials can be made up of particles, but not fibers or sheets.(C). When the reinforcing particles are uniformly distributed in a composite material, there may be a greater tendency for it to have isotropic properties.(D). None of the above is correct.arrow_forwardIf we are talking about viscoelastic modulus or viscoelastic relaxation modulus in polymers, indicate the correct option.(A). It reports the variation of elastic behavior as a function of time.(B). It is only useful for defining its glass transition temperature.(C). It only allows us to define the polymer degradation temperature.(D). Neither option is correct.arrow_forward
- When natural light falls perpendicularly on a material A, it has a reflectivity of 0.813%. Indicate the value of the refractive index.arrow_forwardIn piezoelectricity and piezoelectric ceramics, one of the following options is false:(A). Piezoelectricity allows an electrical signal to be transformed into a mechanical one.(B). PbZrO3 is a well-known piezoelectric ceramic.(C). Piezoelectricity and ferroelectricity in general have no relationship.(D). One of the applications of piezoelectricity is sonar.arrow_forward(30 MARKS) Give the major product(s ) formed including relevant stereochemistry or the complete reaction conditions for the following reactions. More than one step may be required for each reaction arrow, in which case the steps must be numbered 1), 2) etc. (2 marks each box) h) i) h) OH i) HO H3PO4, heat 2 Brarrow_forward
- Nonearrow_forwardIndicate which option is false(A). Resistivity has a residual component and a thermal component.(B). In some materials resistivity increases with T and in others it decreases.(C). In insulating materials, resistivity is very low.arrow_forwardIn ceramic materials, in relation to polymorphism, the same substance crystallizes differently when external conditions vary. Is this correct?arrow_forward
- EBK A SMALL SCALE APPROACH TO ORGANIC LChemistryISBN:9781305446021Author:LampmanPublisher:CENGAGE LEARNING - CONSIGNMENTPrinciples of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning