b. What would be the product if trans-2-butene were used instead of ethene?
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Verified step by step guidance

1. Identify the structure of trans-2-butene, which is an alkene with the formula C4H8, having a double bond between the second and third carbon atoms, and the methyl groups on opposite sides of the double bond.
2. Determine the type of reaction that is being considered. Since the problem mentions ethene, it might be a reaction like hydrogenation, halogenation, or hydrohalogenation.
3. Consider the stereochemistry of the reaction. For example, if it's a hydrogenation reaction, the double bond will be reduced to a single bond, and the product will be butane.
4. If the reaction involves addition of a halogen (e.g., Br2), the product will be a vicinal dibromide, with bromine atoms added to the carbons of the former double bond.
5. Evaluate the stereochemical outcome of the reaction. For example, in a halogenation reaction, the addition of halogens to trans-2-butene will result in an anti addition, leading to a meso compound if the reaction is stereospecific.

Key Concepts

Alkenes and Their Reactions

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond. They are reactive compounds that can undergo various reactions, including addition reactions, where atoms or groups are added across the double bond. Understanding the reactivity of alkenes is crucial for predicting the products of reactions involving them.

Stereochemistry

Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the case of trans-2-butene, the arrangement of substituents around the double bond influences the type of products formed during reactions. Recognizing the stereochemical configuration is essential for understanding the outcome of reactions involving alkenes.

Electrophilic Addition Mechanism

Electrophilic addition is a common reaction mechanism for alkenes, where an electrophile reacts with the double bond, leading to the formation of a more stable carbocation intermediate. This mechanism is key to predicting the products when different alkenes, like trans-2-butene, are used, as the structure of the alkene can affect the regioselectivity and stereochemistry of the final product.