Textbook Question
What product is obtained from ring-opening metathesis polymerization of each of the following compounds? (Hint: In each case, the product is an unsaturated hydrocarbon with a high molecular weight.)
a.
13. Alcohols and Carbonyl Compounds
Organometallic Cumulative Practice
3:51 minutesProblem 23a
Textbook Question
Draw the product of ring-closing metathesis for each of the following compounds:
a. 
Verified step by step guidance1
Identify the functional groups in the given compound that can participate in the ring-closing metathesis (RCM) reaction. Typically, these are alkenes (C=C bonds) that are positioned in such a way that they can form a cyclic structure upon reaction.
Recall the mechanism of ring-closing metathesis. This reaction involves the use of a catalyst, such as a Grubbs catalyst, which facilitates the breaking and reforming of double bonds to create a cyclic product.
Determine the size of the ring that will form. The reaction is most favorable for 5- to 7-membered rings due to minimal ring strain. Analyze the positions of the alkenes in the starting compound to predict the ring size.
Redraw the structure of the compound, showing the newly formed cyclic product. Ensure that the double bond in the product is correctly placed, as the RCM reaction typically results in a single double bond within the ring.
Verify the stereochemistry and regiochemistry of the product, if applicable. Consider whether the reaction could lead to E/Z isomers and ensure the correct representation of the product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Ring-Closing Metathesis (RCM)
Ring-closing metathesis is a reaction in organic chemistry that involves the formation of a ring by the exchange of alkene partners through the use of a catalyst, typically a transition metal complex. This reaction is particularly useful for synthesizing cyclic compounds from linear precursors, allowing for the formation of various ring sizes and structures.
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Alkene Reactivity
Alkenes are hydrocarbons that contain at least one carbon-carbon double bond, making them reactive intermediates in organic reactions. Their reactivity is influenced by factors such as sterics and electronics, which play a crucial role in determining the outcome of reactions like metathesis, where the double bonds are involved in forming new bonds.
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Catalysts in Metathesis
Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. In ring-closing metathesis, catalysts such as Grubbs or Hoveyda catalysts facilitate the exchange of alkene partners, enabling the formation of cyclic structures efficiently. The choice of catalyst can significantly affect the selectivity and yield of the desired product.
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