Textbook Question
Give the expected major product for each reaction, including stereochemistry where applicable.
(a) but-1-ene + H2/Pt
(b) cis-but-2-ene + H2/Ni
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Ch.8 - Reactions of Alkenes
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 8, Problem 23c,d
Give the expected major product for each reaction, including stereochemistry where applicable.
(c) 
(d) 
Verified step by step guidance1
Step 1: Identify the type of reaction. Both reactions involve catalytic hydrogenation using H2 and Pt, which reduces double bonds (π bonds) in alkenes to single bonds (σ bonds). This process adds hydrogen atoms across the double bond.
Step 2: For reaction (c), analyze the structure of the reactant. The reactant is a cyclohexene derivative with one double bond. Hydrogenation will convert the double bond into a single bond, resulting in a saturated cyclohexane ring. The stereochemistry of the product will be relevant if the reaction occurs in a stereoselective manner.
Step 3: For reaction (d), analyze the structure of the reactant. The reactant contains two double bonds: one in the cyclohexene ring and one in the side chain. With excess H2 and Pt, both double bonds will be reduced to single bonds, resulting in a fully saturated hydrocarbon. Ensure to account for the stereochemistry of the product if applicable.
Step 4: Consider the regioselectivity and stereoselectivity of the hydrogenation process. Hydrogenation typically occurs in a syn-addition manner, meaning that both hydrogen atoms are added to the same face of the double bond. This can influence the stereochemistry of the final product.
Step 5: Draw the expected major products for both reactions. For (c), the product will be a cyclohexane derivative with no double bonds. For (d), the product will be a fully saturated hydrocarbon with no double bonds in either the ring or the side chain.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrogenation
Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to an unsaturated compound, typically an alkene or alkyne, in the presence of a catalyst such as platinum (Pt). This process converts double or triple bonds into single bonds, resulting in a saturated compound. Understanding hydrogenation is crucial for predicting the major product of reactions involving alkenes or cyclic compounds.
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The definition of hydrogenation.
Stereochemistry
Stereochemistry refers to the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In reactions like hydrogenation, the stereochemistry of the product can vary based on the orientation of the reactants and the mechanism of the reaction. Recognizing stereochemical outcomes, such as cis or trans configurations, is essential for accurately predicting the major product.
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Catalysis
Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which is not consumed in the reaction. In the context of hydrogenation, platinum serves as a catalyst that facilitates the addition of hydrogen to the substrate. Understanding the role of catalysts is important for predicting reaction pathways and the efficiency of the transformation.
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Related Practice
Textbook Question
The chiral BINAP ligand shown in Figure 8-8 contains no asymmetric carbon atoms. Explain how this ligand is chiral.
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Textbook Question
One of the principal components of lemongrass oil is limonene, C10H16. When limonene is treated with excess hydrogen and a platinum catalyst, the product is an alkane of formula C10H20. What can you conclude about the structure of limonene?
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Textbook Question
Show how you would accomplish the following synthetic conversions.
b. chlorocyclohexane → trans-2-chlorocyclohexanol
Problem-Solving Hint: The opening of a halonium ion is driven by its electrophilic nature. The weak nucleophile attacks the carbon bearing more positive charge.
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Textbook Question
Show how you would accomplish the following synthetic conversions.
c. 1-methylcyclopentanol → 2-chloro-1-methylcyclopentanol
Problem-Solving Hint: The opening of a halonium ion is driven by its electrophilic nature. The weak nucleophile attacks the carbon bearing more positive charge.
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Textbook Question
Predict the carbenoid addition products of the following reactions.
a. trans-hex-3-ene + CH2I2, Zn(Cu)
b. cis-hex-3-ene + CH2I2, Zn(Cu)
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