Correlation of vaporisation enthalpies, Δ^g_lH^o_m(298.15 K), of 1,2-di-methoxy-substituted benzenes with their Kovats's indices (J_x)^a.

Compound	J x b	ΔglHom(298.15 K)exp, kJ mol−1	ΔglHom(298.15 K)calcc, kJ mol−1	Δ d, kJ mol−1
1,2-Di-methoxy-benzene	1146	64.5 ± 0.3 (ref. 5)	64.5	0.0
1,2,3-Tri-methoxy-benzene	1315	73.0 ± 0.5e	72.9	0.1
1,2,4-Tri-methoxy-benzene	1378	75.7 ± 0.5e	76.0	−0.3
3,4,5-Tri-methoxy-toluene	1410	77.7 ± 0.5e	77.6	0.1
2,3,5-Tri-methoxy-toluene	1527	—	83.3	—

^aUncertainty is given as the standard uncertainty (0.683 level of confidence, k = 1).

^bKovats's indices, J_x, on standard non-polar columns from ref. 29.

^cCalculated using eqn (4).

^dDifference between experimental and calculated by eqn (4) values (columns 3 and 4).

^eExperimental data measured by using the transpiration method from (see Table 1).