ORG-06

SN1 rate

r = k [RX]. Unimolecular nucleophilic substitution.

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MechanismsIngold SN1

Governing equation

r=k[RX]

where

k: Rate constant (1/s)
[RX]: Substrate (mol/L)
r: Rate (mol/(L·s))

Lecture brief

Historical brief

Hammett (1937) and Taft linear free-energy, E-factor green metrics, Woodward–Fieser UV and Claisen equilibria are how organic chemistry became predictive. The lab is substituent, waste and tautomer. This sheet (ORG-06 — SN1 rate) is the form associated with Ingold SN1. Working symbols: $k$ , $[RX]$ $\rightarrow$ $r$ . Rate-determining ionisation to a carbocation. Tertiary and resonance-stabilised RX.

Purpose

Purpose: compute

r

from

k

[RX]

in Organic chemistry via

r=k[RX]

r = k [RX]. Unimolecular nucleophilic substitution. Use it when a real organic chemistry question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

k = 0.002\,\mathrm{1/s}

[RX] = 0.100\,\mathrm{mol/L}

, the governing relation

r=k[RX]

yields

r = 2.000e-4\,\mathrm{mol/(L·s)}

. First-order in RX, nucleophile in excess or not in the RDS. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Rate constant k0.002 1/sSubstrate [RX]0.1 mol/L

Outputs

Rate r0.00020 mol/(L·s)

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Narration of this film

First-order in RX, nucleophile in excess or not in the RDS.

Rate-determining ionisation to a carbocation. Tertiary and resonance-stabilised RX.

Reading speed

Watch on YouTube