Organic Chemistry
Improve your experience by picking them
Since ethylcyclopentan-1-ylium is more stable than 2-ethylcyclopentan-1-ylium, provide an energy profile diagram that shows ethylcyclopentan-1-ylium is formed faster than 2-ethylcyclopentan-1-ylium in the reaction below.
Consider the reaction diagram shown below.
a. Determine which step in the forward direction has the highest activation energy.b. Is the second intermediate more likely to return to the first intermediate or to proceed to produce the product?c. What step is the rate-determining step?
Provide an energy profile diagram for an exothermic one-step reaction and label the reactants, products, intermediates, transition states, activation energies (Ea), and ΔG°, if applicable.
The following reaction has an overall ΔH° of −310. kJ/mol (−74.0 kcal/mol) and activation energy of 47.4 kJ/mol (11.3 kcal/mol).
•CH2CH3 + F2 → CH3CH2F + F•
Provide the equation for the reverse reaction, and determine its activation energy.
Write a reaction-energy diagram that corresponds to a one-step exothermic reaction. Make sure that all parts of the diagram are labeled appropriately.
Consider the energy diagram given below:
(1) How many steps are there in the reaction?
(2) Identify the intermediates in the diagram.
(3) Locate the rate-determining step.
(4) Predict whether the Keq of the reaction is less than, greater than, or equal to zero.
The bromination of ethane (CH3CH3) consists of three steps.1. Br2 → 2 Br• ΔH° = +190 kJ/molEa = 190 kJ/mol2. CH3CH3 + Br• —> •CH2CH3 + HBrΔH° = +57 kJ/molEa = 79 kJ/mol3. •CH2CH3 + Br2 —> CH3CH2Br + Br•ΔH° = −113 kJ/molEa = 4 kJ/molWrite a reaction-energy diagram that corresponds to the bromination of X. Make sure you label the rate-limiting step in the diagram.
Consider the following energy profile diagram:
Which will occur at a faster rate: the forward reaction or the reverse reaction?
The following equation is used to calculate the bond angles in a regular polygon with n sides:
180° - 360°/n
Using the above equation, calculate the bond angles in a regular:
(i) pentagon
(ii) hexagon
Which graph below illustrates the reaction coordinate diagram of monohydrobromination of (E)-2-methyl-1,3-hexadiene and monohydrobromination of 2-methyl-1,5-hexadiene?
There are two possible pathways for ionic addition of HBr to 1-ethylcyclohexene. Draw an approximate reaction-energy diagram showing the curves for these pathways.(a) Formation of 1-bromo-1-ethylcyclohexane (major product)(b) Formation of 1-bromo-2-ethylcyclohexane (minor product)
Point out how these curves show that the major product 1-bromo-1-ethylcyclohexane should be formed faster than the minor product 1-bromo-2-ethylcyclohexane.
The reaction of
follows the reaction coordinate diagram shown below.
a. Count the number of intermediate and transition states present.b. Arrange the reaction species in order of increasing stability.c. Which is more stable, the transition state between X and Y, or the transition state between Y and Z?d. Which step has a higher rate constant in the forward direction? In the reverse direction?
Draw the reaction coordinate diagram and label the diagram for a reaction that is slightly endothermic and a three-step reaction in which the second step is the rate-determining step.
Write an appropriate reaction-energy diagram that corresponds to the reaction between methyl radical and HBr shown below:•CH3 + HBr —> CH4 + Br•
Illustrate the energy profile diagram of a one-step reaction with a standard enthalpy change (ΔH°) of 0 kcal/mol and an activation energy (Ea) of 6 kcal/mol.
An alkyl halide is produced from the alkene shown below.
Draw a reaction coordinate diagram for the reaction, taking into account that the product is more stable than the reactant.
Consider a two-step reaction. Provide an energy profile diagram for the reaction, given that it is endothermic, with the second step as the rate-limiting step.
The hydride ion affinity (HIA) is a measure of carbocation stability. The difference in HIA for a secondary allylic carbocation and a tertiary allylic carbocation is 12 kcal/mol. Assuming that this is also the difference in the energies of the transition state for the carbocation formations, estimate the rate difference.
For the following transformation, provide an energy profile diagram, and label all the reactants, products, intermediates, and transition states.
It takes several steps to create product I from reactant A. The reaction proceeds as illustrated in the reaction coordinate diagram below.
a. How many intermediates are generated throughout the synthesis?b. List the letters that correspond to the transition states.c. Identify which step of the reaction is the fastest.d. Between A and I, which one is more stable?e. Does E or I form faster from G?f. Which intermediate is the most stable?
What is the difference in the energies of the transition states of the reactions shown below, which accounts for the differences in rates?
Draw the reaction coordinate diagram and label the diagram for a three-step exothermic reaction where the first step is rate-determining.
Draw the reaction coordinate diagram and label the diagram for a four-step slightly endothermic reaction where the third step is rate-determining.
Determine which of the following reaction coordinate diagrams represents (i) a reaction with a thermodynamically and kinetically stable product and (ii) a reaction with a thermodynamically and kinetically unstable product.
A two-step reaction has an endergonic first step and an exergonic second step. The second step is the rate-determining step, and the overall reaction is exergonic. Provide a reaction coordinate diagram for this reaction and label the reactants, products, transition states, and intermediates.
The loss of a proton from cyclopentanol is shown below:
This process has an acid dissociation constant (Ka) of 4.9×10–16. Construct a reaction diagram for this process.
Draw an approximate reaction-energy diagram for:
(i) The acid-base reaction of p-cresol with 1.00 M NaOH solution
(ii) The acid-base reaction of 3-methylbutan-2-ol with 1.00 M NaOH solution
For the free-radical addition of HBr to 3-methylenepentane:
(i) Draw an approximate reaction-energy diagram for the propagation steps. Show the curves representing the reactions leading to both the Anti-Markovnikov and Markovnikov products.
(ii) Compare the Ea and ∆Gº for the rate-limiting steps.
(iii) Only the Anti-Markovnikov product is obtained. Why is this so?
Consider the reaction shown below:
The reaction was identified to follow the rate law rate = k[2-bromo-2-methylbutane]. Determine the order relative to propan-2-ol.
Under certain conditions, the chlorination of cyclopentene was observed to follow the rate equation rate = k[cyclopentene][Cl2]2. Determine the overall order of the reaction.
Consider the reaction below. The reaction rate triples when the concentration of 1-chloropropane is tripled. The reaction rate quadruples when the concentration of ethanolate is quadrupled.
i) Identify the order of the reaction with respect to 1-chloropropane.
ii) Identify the order of the reaction with respect to ethanolate.
iii) Write the rate law for the reaction.
iv) Identify the overall order of the reaction
The isotope of hydrogen with mass number 2 is called Deuterium (D). The C―D bond is slightly stronger than the C―H bond and because of this, reaction rates tend to be slower when a C―D bond is broken in a rate-limiting step compared to a C―H. This effect, called a kinetic isotope effect, is observed in the comparison of the bromination of methane and tetradeuteriomethane.
In another reaction, the monobromination of deuterioethane (C2H5D) yields a mixture of C2H5Br and C2H4DBr in a 1:10 ratio. Calculate the relative rate of abstraction of H to D.
The reaction between 3-ethyl-3-pentanol and HCl produces 3-chloro-3-ethylpentane.
The rate of the reaction doubles when the concentration of H+ is doubled. The rate of the reaction triples when the concentration of 3-ethyl-3-pentanol is tripled. The rate of reaction is unchanged when the concentration of Cl− is tripled. What is the rate equation for the reaction?
Adding a small amount of platinum to a mixture containing H2 and but-2-ene triggers the following reaction:
The experimental results reveal that changing the concentration of H2 or but-2-ene does not affect the reaction rate. Write the rate equation for this reaction, explain why it is unusual, and provide ways to accelerate this type of reaction.