page 7 Flashcards
Figure 7.1: Classification of Alkyl Halides
Primary Iodide (1° Iodide):
The iodine (I) is attached to a primary carbon.
Primary (1°): The carbon bonded to I is connected to only one other carbon.
Example:
CH3CH2CH2CH2ICH 3.
Secondary Bromide (2° Bromide):
The bromine (
Br) is attached to a secondary carbon.
Secondary (2°): The carbon bonded to
Br is connected to two other carbons.
Example: Bromine attached to a carbon in a cyclohexane ring.
Tertiary Chloride (3° Chloride):
The chlorine (Cl) is attached to a tertiary carbon.
Tertiary (3°): The carbon bonded to
Cl is connected to three other carbons.
Example:
CH3C(Cl)CH2CH3.
Types of Organic Halides
Vinyl Halide:
The halogen (X) is attached to an sp²-hybridized carbon in a C=C double bond.
Key Feature: These are unreactive in nucleophilic substitution reactions due to the strength of the double bond and restricted access for nucleophiles.
Aryl Halide:
The halogen (X) is attached directly to a benzene ring (sp²-hybridized carbon).
Key Feature: Aryl halides are unreactive in nucleophilic substitution due to electron delocalization in the benzene ring, which stabilizes the C-X bond.
Allylic Halide:
The halogen (X) is attached to a carbon atom adjacent to a C=C double bond.
Key Feature: These are reactive due to resonance stabilization of intermediates in nucleophilic substitution reactions.
Benzylic Halide:
The halogen (X) is attached to a carbon atom adjacent to a benzene ring (sp³-hybridized carbon).
Key Feature: These are highly reactive due to resonance stabilization of intermediates.
What is the defining characteristic of a primary halide?
Answer: The halogen is attached to a carbon bonded to only one other carbon atom.
Give an example of a secondary bromide.
Answer: Bromine attached to a carbon in cyclohexane.
Why are tertiary halides highly reactive in SN1 reactions?
Answer: The tertiary carbon forms a stable carbocation intermediate due to hyperconjugation and inductive effects.
What is a vinyl halide?
Answer: A halogen (X) attached to a carbon in a C=C double bond.
Where is the halogen attached in an allylic halide?
Answer: To a carbon atom adjacent to a C=C double bond.
Give an example of a benzylic halide.
Answer: Benzyl chloride (
C6H5CH2Cl
Why are allylic and benzylic halides more reactive?
Answer: The allylic and benzylic carbocations are stabilized by resonance, making them favorable for substitution reactions.
Which types of organic halides are unreactive in Chapter 7 reactions?
Answer: Vinyl halides and aryl halides.
