Draw a mechanism for the acid-catalyzed conversion of DPP to IPP. How do you know that your mechanism is correct?

Verified step by step guidance

1. Identify the structures of DPP (Dimethylallyl pyrophosphate) and IPP (Isopentenyl pyrophosphate). Both are isomers and intermediates in the mevalonate pathway. DPP has a double bond at the terminal position, while IPP has a double bond in the internal position.
2. Recognize that the reaction is acid-catalyzed. This means a proton (H⁺) will be added to initiate the reaction. The acid catalyst will protonate the terminal double bond of DPP, forming a carbocation intermediate.
3. Draw the carbocation intermediate. Protonation of the double bond in DPP will result in a more stable secondary carbocation due to hyperconjugation and inductive effects.
4. Show the rearrangement of the carbocation. A 1,2-hydride shift occurs, where a hydrogen atom from the adjacent carbon migrates to stabilize the carbocation, forming a new carbocation at a different position.
5. Deprotonate the carbocation to regenerate the double bond in a new position, resulting in the formation of IPP. Verify the mechanism by ensuring that all steps follow the principles of stability (e.g., carbocation stability) and that the final product matches the structure of IPP.

Key Concepts

Acid-Catalyzed Reactions

Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In organic chemistry, acids can donate protons (H+) to substrates, facilitating the formation of reactive intermediates. Understanding how acids interact with molecules is crucial for predicting the pathway and products of the reaction, such as the conversion of DPP to IPP.

Reaction Mechanism

A reaction mechanism is a step-by-step description of the process by which reactants are converted into products. It outlines the sequence of bond-breaking and bond-forming events, including the formation of intermediates. Drawing a mechanism helps visualize the transformation of DPP to IPP, allowing chemists to understand the roles of various species and the overall energy changes involved.

Verification of Mechanisms

Verifying a reaction mechanism involves checking its consistency with experimental data and established chemical principles. This can include analyzing reaction rates, intermediates, and product distributions. A correct mechanism should align with known reactivity patterns and provide a plausible explanation for the observed outcomes, ensuring that the proposed steps are feasible under the given conditions.