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for dichloromethane. Final free energies were calculated by adding
the thermodynamic corrections from the frequency calculation to
the calculated free energies in solvent.
molecular and kinetic modeling, the overall reaction was
shown to proceed according to a mechanism involving at least
two reaction cycles consisting of six reactions. Moreover, the
results show that the formation of ethyl acetate and acetalde-
hyde can be considered to influence significantly the overall
reaction rate. A two-cycle model that fully concurred with the
reaction mechanism used in the DFT calculation and in addi-
tion to product inhibition observed for ethyl acetate was de-
veloped. However, a simpler one-cycle model incorporating
the main features of the two-cycle model was also introduced
to decrease the model complexity in line with the amount of
available experimental data.
Acknowledgements
This work is part of the activities at the Johan Gadolin Process
Chemistry Centre, a Centre of Excellence financed by bo Akade-
mi University. Financial support to R.S. from the National Doctor-
al Program of Organic Chemistry and Chemical Biology (2010–
2013), Stiftelsen fçr bo Akademi, Kemian päivien säätiç, Orion
Farmos Research Foundation and Magnus Ehrnrooth Foundation
is gratefully acknowledged.
Overall, both the theoretical investigation of the transition
states and the mathematical modeling of the reaction kinetics
support the conclusions made in the present paper. The results
increase considerably the current understanding of the overall
reaction mechanism involved in the chlorination reaction and
may help in its further development towards practical applica-
tions.
Keywords: DFT calculations · halogenation · iron · kinetics ·
silanes
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Experimental Section
General considerations
on, Aldrichimica Acta 2010, 43, 3–12.
All chemicals and reagents were purchased from commercial sour-
ces and were used without further purification unless mentioned
otherwise. Acetyl chloride (reagent grade 98%) and iron(III) chlo-
ride (97%) were purchased from Sigma–Aldrich and used without
further purification. The product distribution and purity were moni-
tored by GC–FID using HP-5 column (50 m320 mm17 mm) and
H2 as the carrier gas with the following temperature program: in-
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1 min. The kinetic experiments were conducted at ambient pres-
sure at RT (23Æ18C) by using a magnetic stirrer. Dichloromethane
(5 mL) was used as the solvent and 1.26 molLÀ1 concentration of
triphenylsilane or triisopropylsilane reagent was applied in all ex-
periments.
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General method for the kinetic measurements
The corresponding silane (6.3 mmol) and iron(III) chloride (0.5%:
5.1 mg, 0.03 mmol; 1.0%: 10.2 mg, 0.06 mmol; 2.0%: 20.4 mg,
0.13 mmol) were dissolved in dry dichloromethane (5 mL) resulting
in a yellow or murky brown solution. Acetyl chloride (1.0 equiv.:
0.45 mL, 6.3 mmol; 1.25 equiv.: 0.56 mL, 7.9 mmol; 1.5 equiv.:
0.67 mL, 9.5 mmol) was added to the reaction mixture and the re-
action was followed for 24 h.
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Computational details
All calculations were performed in Jaguar[16] using B3LYP-D3/
LACVP*. The B3LYP-D3 functional combines the original B3LYP
functional[17] with corrections for dispersion interactions.[18] The
LACVP* basis uses the 6-31G* basis set for light elements, and the
Hay–Wadt ECP with accompanying basis set for Fe.[19] Stationary
points were validated by frequency calculations, and transition
states were further validated by QRC[20] calculations. Energies in
solvent were calculated with the PBF method[21] using parameters
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