The title compound, C12H13ClN2O2, crystallizes with two independent but very similar mol­ecules (A and B) in the asymmetric unit. The pyrazole ring in each mol­ecule has an envelope conformation. The dihedral angle between the pyrazole ring mean plane and the benzene ring is 86.07 (14)° in A and 85.99 (14)° in B. In the crystal, the A and B mol­ecules are linked via a pair of O—H⋯O hydrogen bonds, forming dimers. These dimers are further linked via C—H⋯O inter­actions to form –A–B–A–B– chains propagating along the c-axis direction.

In the two independent but very similar mol­ecules (A and B) of the title compound, C14H16N2O8, both six-membered pyrimidine rings are nearly planar [maximum deviations = 0.010 (3) Å in A and 0.028 (3) Å in B]. The five-membered furan­ose ring in mol­ecule A adopts an envelope conformation, while the same ring in mol­ecule B has a twisted conformation. In the crystal, the A mol­ecules are linked via a pair of inter­molecular N—H⋯O hydrogen bonds, forming dimers. Each A mol­ecule is further linked to a B mol­ecule via a second N—H⋯O hydrogen bond. There are also a number of C—H⋯·O inter­actions present, leading to the formation of a three-dimensional network.

In the crystal structure of the title compound, C8H6N2O3, the mol­ecules are linked by a pairs of inter­molecular N—H⋯O hydrogen bonds, forming inversion dimers. The aldehyde group is in the same plane as the pyrimidine ring [with a maximum deviation of 0.083 (2) Å for the O atom), and the linear propargyl group [C—C—C = 178.99 (19)°] makes a dihedral angle of 74.36 (13)° with the ring.

In the structure of the title compound, C20H15BrN4O·C2H6O, the hydrogenated pyridinone ring adopts an envelope conformation. The dihedral angle between the bromo-substituted phenyl ring and the pyrazole ring is 79.6 (1)°, and that between the non-substituted phenyl ring and the pyrazole ring is 51.2 (1)°. In the crystal structure, mol­ecules are linked via inter­molecular N—H⋯O and O—H⋯N hydrogen bonds. A short inter­molecular N⋯Br contact [3.213 (4) Å] is present in the crystal structure.

In the title compound, C21H16N4O2, the dihedral angle between the meth­oxy-substituted benzene ring and the ring system formed by the pyridinone ring and the pyrazole ring is 57.4 (1)°, and that between the unsubstituted phenyl ring and the ring system is 135.6 (1)°. In the crystal structure, mol­ecules are linked together via inter­molecular N—H⋯O hydrogen bonds.

In the crystal structure of the title compound, C20H16ClN5, the dihedral angle between the pyrazole ring and the phenyl ring is 54.7 (1)° and that between the pyrazole ring and the chloro-substituted phenyl ring is 72.4 (1)°. The methyl H atoms are disordered over two positions with site occupancy factors of ca 0.7 and 0.3. One amino H is disordered equally over two positions. In the crystal structure, the mol­ecules are linked via inter­molecular N—H⋯N hydrogen bonding.

The title compound, C20H14N6O2, contains four rings. The dihedral angle between the pyridine ring and the pyrazole ring is 1.9 (1)°, i.e. almost coplanar, which gives rise to a conjugated structure. The dihedral angle between the nitro-substituted phenyl ring and the pyridine ring is 76.3 (1)° and that between the pyrazole ring and the non-substituted phenyl ring is 40.5 (1)°. In the crystal structure, symmetry-related mol­ecules are linked by N—H⋯O and C—H⋯N hydrogen bonds.