Concept explainers
Interpretation:
The statement “entropy for ring closure in ring closing metathesis is not large for most systems” is to be explained.
Concept introduction:
Ring closing metathesis is a process in
These reactions are catalyzed by metal complexes. Grubbs II reagent is a ruthenium-based carbene complex used as a catalyst in ring closing metathesis. These catalysts can form di-substituted or tri-substituted alkenes.
The
The entropy for ring closure in ring closing metathesis is not large as these reactions have enthalpy favorability.
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Organic Chemistry
- A problem often encountered in the oxidation of primary alcohols to acids is that esters are sometimes produced as by-products. For example, oxidation of ethanol yields acetic acid and ethyl acetate: Propose a mechanism to account for the formation of ethyl acetate. Take into account the reversible reaction between aldehydes and alcohols:arrow_forwardAlkyl halides undergo nucleophilic substitution and elimination reactions. When the kinetics of the reaction are measured, if the rate of the reaction is found to be dependent only upon the concentration of the alkyl halide the reaction is first order. The substitution reaction is thus termed SN1, and the elimination reaction is termed E1. These reactions are unimolecular and occur in two steps. The first step is rate-limiting and involves the loss of the leaving group to form a carbocation. In the second, fast, step the nucleophile adds to the carbocation in the SN1 reaction or elimination occurs to give an alkene in the E1 reaction. Because the carbocation is planar, the nucleophile can add to either face and therefore racemization is usually observed although solvent effects can influence this somewhat. E1 elimination follows Zaitsev’s rule and typically yields the most substituted alkene as the major product. Conditions which favor the SN1/E1 pathway include the use of a weak…arrow_forwardAlkyl halides undergo nucleophilic substitution and elimination reactions. When the kinetics of the reaction are measured, if the rate of the reaction is found to be dependent only upon the concentration of the alkyl halide the reaction is first order. The substitution reaction is thus termed SN1, and the elimination reaction is termed E1. These reactions are unimolecular and occur in two steps. The first step is rate-limiting and involves the loss of the leaving group to form a carbocation. In the second, fast, step the nucleophile adds to the carbocation in the SN1 reaction or elimination occurs to give an alkene in the E1 reaction. Because the carbocation is planar, the nucleophile can add to either face and therefore racemization is usually observed although solvent effects can influence this somewhat. E1 elimination follows Zaitsev’s rule and typically yields the most substituted alkene as the major product. Conditions which favor the SN1/E1 pathway include the use of a weak…arrow_forward
- Illustrate the resonance effect of the methoxy group -OCH3, on the structure of the benzene ring. Draw all the oissuvke resonance forms of methoxybenzene, including the hybrid Based on the structures, explain how the presence of the -OCH3 group affects: (i) the reactivity of the benzene ring towards electrophilic attack (ii) the orientation or point of attack of an incoming electrophilic reagent on the benzene ring.arrow_forwardIn the early age of the development of Organometallilc Chemistry, the preparation of Organometallic Compound containing M-R(R: alkyl group) bond always led to the decomposition of the M-R bond. It was later known to be caused by the so called “beta-hydrogen elimination” process. Which of the following statements is not correct? This process can be prevented by using all halogenated alkyl group. This process can be prevented by carrying out reaction at high temperature. The Grignard’s reagent, RMgX or R2Mg is stable and does not undergo “b-hydrogen elimination” process. The anti-knocking agent, Pb(C2H5)4 is stable and does not undergo “b-hydrogen elimination” process. The ferrocene, Cp2Fe, is free from the “b-hydrogen elimination” process.arrow_forwardDo hydration reactions like this one have Markovnikov and anti-Markovnikov products? I know that for addition of halides on alkene double bonds, there are Markovnikov products becasue of 1,2-halide/methyl shifts, but there usually aren't shifts in hydration reactions. Essentially, would the Markovnikov/major product for this reaction have a hydroxy group attached to the tertiary carbocation and the anti-Markovnikov/minor product for this reaction have a hydroxy group attached to the adjacent secondary carbocation?arrow_forward
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- 4. A certain endothermic reaction X carried out room temperature (273K) has an enthalpy change of 20 Kcal/mol and an entropy change of 10 Kcal/K/mol. i) Calculate the Gibbs free energy (AG) of this reaction. ii) Is this reaction spontaneous or non-spontaneous? Give a reason for your answer 5. Thiomethane reacts with compound A via an SN1 reaction. Complete its reaction equation below. ii) SH Compound A ii) Draw the mechanism of reaction for this reaction. 6. Butyl Chloride undergoes an elimination reaction when reacted with sodium ethoxide to form butene. The reaction equation is given below with two reaction products A and B. low inevloa CI noitsups p *OEt B Which is the major product, and which is minor product. (Hint: Look up how the size of the base affects the elimination reaction product) Give a reason for your answer.arrow_forwardThe analogous reaction of trans-1,2-dichloroethylene with benzyne produces the same cis- and trans- products but in a 0.230: 1 ratio. 1) Derive two expressions for the predicted cis: trans product ration starting from cis- and trans- 1,2-dichloroethylene on the basis of the proposed mechanism. 2) Calculate the rate constant ration k1/k2 and k3/k-1 from the observed product ratios.arrow_forwardAcyl transfer (nucleophilic substitution at carbonyl) reactions proceed in two stages via a "tetrahedral intermediate." Draw the tetrahedral intermediate as it is first formed in the following reaction. H3C NH₂ HCI/H₂O reflux • You do not have to consider stereochemistry. • Include all valence lone pairs in your answer. • Do not include counter-ions, e.g., Na+, I, in your answer. • In cases where there is more than one answer, just draw one.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage LearningOrganic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage Learning