Comparison of the experimental, Δ_fH^o_m(g)_exp, and theoretical, Δ_fH^o_m(g)_theor, gas-phase standard molar enthalpies of formation of methoxy-substituted benzenes at T = 298.15 K and p° = 0.1 MPa (in kJ mol⁻¹).

Compound	ΔfHom(g)exp	G4	G4	G3MP2	G3MP2	M06/QZ4P	M06/QZ4P	ΔfHom(g)theor
	Exp.a	ATb	WBRc	ATb	WBRc	ATb	WBRc	Average
1,2,3-Trimethoxybenzene	−346.0 ± 2.0	−351.8	−352.2	−350.2	−351.5	−348.3	−349.3	−350.6 ± 2.4
1,2,4-Trimethoxybenzene	−360.6 ± 2.3	−360.7	−361.0	−359.8	−361.1	−358.5	−360.8	−360.3 ± 1.6
1,3,5-Trimethoxybenzene	−381.6 ± 3.2	−382.0	−382.3	−381.1	−382.2	−381.5	−383.4	−382.1 ± 1.2
3,4,5-Trimethoxytoluene	−383.2 ± 2.5	−383.4	−381.8	−382.3	−381.2	−381.6d	−382.1e	−382.1 ± 1.2

^aFrom Table 7. The uncertainties are given as the twice standard deviation.

^bCalculated by the G4, G3MP2, or M06/QZ4P method according to the standard atomization procedure and corrected with empirical equations specific for each method (see text).

^cCalculated by the G4, G3MP2 or M06/QZ4P methods with help of reactions (R1)–(R4) using experimental Δ_fH^o_m(g)-values for the reaction participants (see Table S7). Numerical data for reactions (R1)–(R4) are given in Tables S11 to S14 in ESI.

^dCalculated by the G4MP2 according to the standard atomization procedure.

^eCalculated by the G4MP2 method with help of reaction (R4) using experimental values for the reaction participants (see Table S6). Numerical data for reaction (R4) is given in Table S13 in ESI.