Before detailing specific answers, it is essential to establish the theoretical framework used in the Chemsheets tasks.
Complete the sheet, then compare:
| Your mechanism | Key checkpoints | |----------------|------------------| | SN2 | Curly arrow from nucleophile lone pair to δ⁺ C; curly arrow from C–Br bond to Br; transition state; products with inverted stereochemistry. | | SN1 | Step 1: C–Br breaks heterolytically – arrow to Br, carbocation formed; Step 2: nucleophile attacks carbocation. | | E2 | Base abstracts H from β-carbon; simultaneous C–Halogen bond breaks; alkene formed; all in one step. |
This is the most common reaction on the worksheet. reactions of halogenoalkanes 1 chemsheets answers exclusive
The Reagent: Aqueous sodium hydroxide or potassium hydroxide (OH⁻). The Condition: Warm, aqueous solution. The Product: Alcohol. The Mechanism: Nucleophilic Substitution (SN1 or SN2 depending on the structure).
Reaction: Nucleophilic substitution – adds 1 carbon.
Example:
CH₃CH₂Br + KCN (ethanol, reflux) → CH₃CH₂CN + KBr Before detailing specific answers, it is essential to
Product name: propanenitrile (from bromoethane).
Mechanism: SN2 (if 1° or 2°).
Common nucleophiles in Chemsheets exercises:
This is the advanced section on Chemsheets 1 that separates A/A* students from B/C students. This is the most common reaction on the worksheet
Both reactions start with the same halogenoalkane and a base/nucleophile (e.g., OH⁻). The outcome depends on:
| Factor | Favors Substitution (SN2 or SN1) | Favors Elimination (E2 or E1) | |---|---|---| | Temperature | Lower temp (25°C) | Higher temp (>60°C, reflux) | | Nucleophile/Base | Strong nucleophile, weak bulky base (e.g., OH⁻, CN⁻, NH₃) | Strong, bulky base (e.g., KOH in ethanol, not water; or tert-butoxide) | | Halogenoalkane structure | Primary (SN2 only); Tertiary (SN1) | Tertiary (E1 or E2); primary needs strong bulky base (E2) | | Solvent | Polar protic (water, alcohols) for SN1; Polar aprotic (DMSO, acetone) for SN2 | Polar protic also works; non-polar favors E2 |
Classic Chemsheets Question: “1-bromopropane is heated with NaOH(aq) and separately with NaOH in ethanol. State the major product in each case and explain.”
Your Exclusive Answer:
