Gas phase B3LYP/6-311G(d,p) relative electronic energies of transition states (TS) and the corresponding products (P) associated with the proposed mechanisms for the formation of barbituric acid (BA) and 2,4,6-triaminopyrimidine (TAP). Electronic energies are calculated using the gas phase B3LYP/6-311G(d,p) optimized geometries, and are reported relative to the energies of the reactants^a.

Relative energies for BA formation (in kcal mol−1)			Relative energies for TAP formation (in kcal mol−1)
Conversion	TS	P	Conversion	TS	P
29 → 30	4.8	2.4	37 + 20b → 38	10.0	−9.6
30 + 31 → 32	8.9	5.8	38 → 39	0	10.8
32 → 33	12.1	7.7	39 → 40	3.3	−8.3
33 → 34	5.5	2.1	40 → 41	8.2	−13.3
34 → 35	13.1	1.5	41 → 42	10.3	9.5
35 → 36	11.1	5.2	42 → 43	3.4	−2.7
			43 → 44	2.4	−6.2
			44 → 45	13.6	−20.2

^aEach reactant is considered in its free optimized state while calculating the electronic energies.