Iodine Activation of Alcohols: A Computational Study
A DFT study aimed at unravelling the origin of catalytic activity of iodine in reaction with alcohols is presented. Computed free energies for generation of the O–I complexes from the separated reactants are around 3 kcal/mol and solvation increases endoergicity by ca. 1 kcal/mol. Calculations suggest that halogen bond formation between I2 and alcohols does not lead to strong activation of the hydroxyl as a leaving group, although solvent has a notable effect in lowering endoergicity for carbocation formation. Model tertiary alcohols exhibited β-proton abstraction following breaking of the C–O bond, while model secondary and primary alcohols experienced an earlier β-proton abstraction, synchronic with the C–O bond cleavage. Consistent with computed natural bond orbital charges, benzylic and propargylic alcohols underwent iodide anion quenching at the para position of phenyl and C-3, respectively.
KeywordsCatalysis by iodine Halogen bonding DFT calculations Activation of alcohols
We thank the University of Florida for access to computational facilities at UF High-Performance Computing Center. Access to computational resources at Mendieta cluster from CCAD-UNC, which is part of SNCAD-MinCyT, Argentina, is also acknowledged. GLB acknowledges funding from CONICET and Secyt-UNC. S. S. acknowledges the Slovenian Research Agency (Programme P1-0134) for financial support and helpful discussions with Dr. Anton Kokalj (Jožef Stefan Institute).
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
- 18.Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR, Montgomery JA Jr, Vreven T, Kudin KN, Burant JC, Millam JM, Iyengar SS, Tomasi J, Barone V, Mennucci B, Cossi M, Scalmani G, Rega N, Petersson GA, Nakatsuji H, Hada M, Ehara M, Toyota K, Fukuda R, Hasegawa J, Ishida M, Nakajima T, Honda Y, Kitao O, Nakai H, Klene M, Li X, Knox JE, Hratchian HP, Cross JB, Bakken V, Adamo C, Jaramillo J, Gomperts R, Stratmann RE, Yazyev O, Austin AJ, Cammi R, Pomelli C, Ochterski JW, Ayala PY, Morokuma K, Voth GA, Salvador P, Dannenberg JJ, Zakrzewski VG, Dapprich S, Daniels AD, Strain MC, Farkas O, Malick DK, Rabuck AD, Raghavachari K, Foresman JB, Ortiz JV, Cui Q, Baboul AG, Clifford S, Cioslowski J, Stefanov BB, Liu G, Liashenko A, Piskorz P, Komaromi I, Martin RL, Fox DJ, Keith T, Al-Laham MA, Peng CY, Nanayakkara A, Challacombe M, Gill PMW, Johnson B, Chen W, Wong MW, Gonzalez C, Pople JA (2009) Gaussian 09, Revision E.01, Gaussian, Inc, Wallingford, CTGoogle Scholar
- 26.Glendening ED, Reed AE, Carpenter JE, Weinhold F (2009) NBO Version 3.1. Gaussian, Inc, Wallingford, CTGoogle Scholar