Notes

Site:	Prefrontal Learning Center
Course:	03 Mechanism
Book:	Notes

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Date:	Friday, 20 September 2024, 5:46 AM

1. Verify Suggested Mechanism Using Experimental Rate Equation

Overall reaction	Mechanism 01	Mechanism 02
\( 2A + B \rightarrow A_2B \)	Step 01: \( A + A \rightarrow A_2 \) (slow) Step 02: \( A_2 + B \rightarrow A_2B \)	Step 01: \( A + B \rightarrow AB \) (slow) Step 03: \( AB + A \rightarrow A_2B \)
Reaction can be experimentally determined as	\( \text{Rate} = k[A]^2 \)	Rate = k [A][B]

1.1. Autocatalytic Reactions

Overall reaction	Mechanism 01	Mechanism 02
\( 2A + B \rightarrow C \)	Step 01: \( A + B \rightarrow C \) (slow) Step 02: \( C + A \rightarrow C + A \) (autocatalysis)	Step 01: \( A + A \rightarrow D \) (slow) Step 02: \( D + B \rightarrow C + A \) (autocatalysis)
Rate Law	\( \text{Rate} = k[A][B] \)	\( \text{Rate} = k[A]^2 \)

1.2. Catalyst Involvement

Overall reaction	Mechanism 01	Mechanism 02
\( M + N \rightarrow P \)	Step 01: \( M + N \rightarrow MN \) (slow) Step 02: \( MN + C \rightarrow MNC \) Step 03: \( MNC \rightarrow P + C \)	Step 01: \( N + C \rightarrow NC \) (slow) Step 02: \( NC + M \rightarrow NCM \) Step 03: \( NCM \rightarrow P + C \)
Rate Law	\( \text{Rate} = k[M][N] \)	\( \text{Rate} = k[N][C] \)

1.3. Chain Reactions

Overall reaction	Mechanism 01
\( A + B + C \rightarrow ABC + D \)	Step 01: \( A + B \rightarrow AB^* \) (initiation, slow) Step 02: \( AB^* + C \rightarrow ABC + D \) (propagation)
Rate Law	\( \text{Rate} = k[A][B] \)

1.4. Competing Pathways

Overall reaction	Mechanism 01
\( E + F + G \rightarrow H \)	Step 01: \( E + F \rightarrow EF \) (slow) Step 02: \( EF + G \rightarrow EFG \) Step 03: \( EFG \rightarrow H \)
Rate Law	\( \text{Rate} = k[E][F] \)

1.5. Complex Formation

Overall reaction	Mechanism 01
\( M + L + X \rightarrow MLX \)	Step 01: \( M + L \rightarrow ML \) (slow) Step 02: \( ML + X \rightarrow MLX \)
Rate Law	\( \text{Rate} = k[M][L] \)

1.6. Concerted Reactions

Overall reaction	Mechanism 01	Mechanism 02
\( Q + R \rightarrow S \)	Step 01: \( Q + R \rightarrow QR^* \) (slow) Step 02: \( QR^* \rightarrow S \)	Step 01: \( Q + R \rightarrow QR \) (slow) Step 02: \( QR \rightarrow S \)
Rate Law	\( \text{Rate} = k[Q][R] \)	\( \text{Rate} = k[Q][R] \)

1.7. Electrophilic Addition

Overall reaction	Mechanism 01
\( E + F + G \rightarrow EFG \)	Step 01: \( E + F \rightarrow EF^+ \) (slow) Step 02: \( EF^+ + G \rightarrow EFG \)
Rate Law	\( \text{Rate} = k[E][F] \)

1.8. Elimination Reactions

1.9. Enzyme-Catalyzed Reactions

Overall reaction	Mechanism 01
\( E + S \rightarrow E + P \)	Step 01: \( E + S \rightarrow ES \) (slow) Step 02: \( ES \rightarrow E + P \)
Rate Law	\( \text{Rate} = k[E][S] \)

1.10. Step 01

Overall reaction	Mechanism 01
\( K + L \rightarrow K + L^- \)	Step 01: \( K + L \rightarrow KL^- \) (slow) Step 02: \( KL^- \rightarrow K + L^- \) (elimination)
Rate Law	\( \text{Rate} = k[K][L] \)

1.11. Step 02

Overall reaction	Mechanism 01
\( K + L^- \rightarrow K + L \)	Step 01: \( K + L^- \rightarrow KL^- \) (slow) Step 02: \( KL^- \rightarrow K + L \) (elimination)
Rate Law	\( \text{Rate} = k[K][L^-] \)

1.12. Formation of Product via Intermediates

Overall reaction	Mechanism 01
\( A + B + D \rightarrow E \)	Step 01: \( A + B \rightarrow C \) (slow) Step 02: \( C + D \rightarrow E \)
Rate Law	\( \text{Rate} = k[A][B] \)

1.13. Multiple Intermediates

Overall reaction	Mechanism 01
\( A + B + C + D \rightarrow E \)	Step 01: \( A + B \rightarrow AB \) (slow) Step 02: \( AB + C \rightarrow ABC \) Step 03: \( ABC + D \rightarrow E \)
Rate Law	\( \text{Rate} = k[A][B] \)

1.14. Nucleophilic Substitution

Overall reaction	Mechanism 01
\( H + I + J \rightarrow HJ \)	Step 01: \( H + I \rightarrow HI^- \) (slow) Step 02: \( HI^- + J \rightarrow HJ \)
Rate Law	\( \text{Rate} = k[H][I] \)

1.15. Nucleophilic Substitution

Overall reaction	Mechanism 01
\( H + I + J \rightarrow HJ \)	Step 01: \( H + I \rightarrow HI^- \) (slow) Step 02: \( HI^- + J \rightarrow HJ \)
Rate Law	\( \text{Rate} = k[H][I] \)

1.16. Parallel pathways

Overall reaction	Mechanism 01
\( X + Y + Z \rightarrow XYZ \)	Step 01: \( X + Y \rightarrow XY \) (slow) Step 02: \( XY + Z \rightarrow XYZ \)
Rate Law	\( \text{Rate} = k[X][Y] \)

1.17. Photochemical Reactions

Overall reaction	Mechanism 01
\( A + B \rightarrow AB \)	Step 01: \( A + h\nu \rightarrow A^* \) (light absorption, slow) Step 02: \( A^* + B \rightarrow AB \)
Rate Law	\( \text{Rate} = k[A][h\nu] \)

1.18. Pre-equilibrium Mechanisms

Overall reaction	Mechanism 01
\( A + B + C \rightarrow ABC \)	Step 01: \( A + B \rightleftharpoons AB \) (fast equilibrium) Step 02: \( AB + C \rightarrow ABC \) (slow)
Rate Law	\( \text{Rate} = k[AB][C] \)

1.19. Radical Reactions

Overall reaction	Mechanism 01
\( R_1 + B \rightarrow R_2B \)	Step 01: \( R_1 \rightarrow R_2^* \) (slow) Step 02: \( R_2^* + B \rightarrow R_2B \)
Rate Law	\( \text{Rate} = k[R_1] \)

1.20. Redox Reactions

Overall reaction	Mechanism 01	Mechanism 02
\( A_{red} + B_{ox} \rightarrow A_{ox} + B_{red} \)	Step 01: \( A_{red} \rightarrow A_{ox} + e^- \) (oxidation, slow) Step 02: \( B_{ox} + e^- \rightarrow B_{red} \) (reduction)	Step 01: \( B_{ox} \rightarrow B_{red} + e^- \) (reduction, slow) Step 02: \( A_{red} + e^- \rightarrow A_{ox} \) (oxidation)
Rate Law	\( \text{Rate} = k[A_{red}] \)	$Rate=k[Box]\text{Rate} = k[B_{ox}]$ $Rate = k [B_{o x}]$

1.21. Sequential Reactions

Overall reaction	Mechanism 01
\( P + Q + R \rightarrow PQR \)	Step 01: \( P + Q \rightarrow PQ \) (slow) Step 02: \( PQ + R \rightarrow PQR \)
Rate Law	\( \text{Rate} = k[P][Q] \)

1.22. SN1 Reaction Mechanism

Overall reaction	Mechanism 01
\( R-LG + N \rightarrow R-N + LG^- \)	Step 01: \( R-LG \rightarrow R^+ + LG^- \) (slow, rate-determining step) Step 02: \( R^+ + N \rightarrow R-N \) (fast)
Rate Law	\( \text{Rate} = k[R-LG] \)

1.23. SN2 Reaction Mechanism

Overall reaction	Mechanism 01
\( R-LG + Nu^- \rightarrow R-Nu + LG^- \)	Step 01: \( R-LG + Nu^- \rightarrow R-Nu + LG^- \) (single step, bimolecular)
Rate Law	\( \text{Rate} = k[R-LG][Nu^-] \)

1.24. Surface Catalysis

Overall reaction	Mechanism 01
\( A + B \rightarrow AB \)	Step 01: \( A + S \rightarrow AS \) (adsorption, slow) Step 02: \( AS + B \rightarrow AB + S \) (reaction on surface)
Rate Law	\( \text{Rate} = k[A][S] \)