To explain why (CH 3 ) 2 CHCH(Br) CH 2 CH 3 reacts faster than (CH 3 ) 2 CHCH 2 CH(Br) CH 3 in an E2 reaction. Concept introduction: The most common mechanism for dehydrohalogenation is the E2 mechanism. An E2 reaction exhibits a second-order kinetics, in which the reaction is bimolecular and both the alkyl halide and the base appear in the rate equation. The most straightforward explanation for the second-order kinetics is a concerted reaction: all bonds are broken and formed in a single step. In other words simultaneously all bonds are broken and formed. The transition state of an E2 reaction consists of four atoms from the alkyl halide-one hydrogen atom, two carbon atoms, and the leaving group (X)-all aligned in the same plane. There are two ways for the C-H and C-x bonds to be coplanar. When the H and X atoms oriented on the same side of the molecule. This geometry is called syn periplanar. While the H and X atoms oriented on opposite sides of the molecule. This geometry is called anti periplanar. The dihedral angle for the C-H and C-X bonds equals 0° for the syn periplanar arrangement and 180° for the anti periplanar arrangement.

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2. Draw the arrows required to make the following reactions occur. Please ensure your arrows point from exactly where you want to exactly where you want. If it is unclear from where arrows start or where they end, only partial credit will be given. Note: You may need to draw in lone pairs before drawing the arrows. A. B. H-Br 人 C Θ CI H Cl Θ + Br O

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Chapter 8, Problem 8.37P

Interpretation Introduction

Interpretation:

To explain why (CH₃)₂CHCH(Br) CH₂CH₃ reacts faster than (CH₃)₂CHCH₂CH(Br) CH₃ in an E2 reaction.

Concept introduction:

The most common mechanism for dehydrohalogenation is the E2 mechanism. An E2 reaction exhibits a second-order kinetics, in which the reaction is bimolecular and both the alkyl halide and the base appear in the rate equation. The most straightforward explanation for the second-order kinetics is a concerted reaction: all bonds are broken and formed in a single step. In other words simultaneously all bonds are broken and formed.

The transition state of an E2 reaction consists of four atoms from the alkyl halide-one hydrogen atom, two carbon atoms, and the leaving group (X)-all aligned in the same plane. There are two ways for the C-H and C-x bonds to be coplanar. When the H and X atoms oriented on the same side of the molecule. This geometry is called syn periplanar. While the H and X atoms oriented on opposite sides of the molecule. This geometry is called anti periplanar. The dihedral angle for the C-H and C-X bonds equals 0° for the syn periplanar arrangement and 180° for the anti periplanar arrangement.

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