6,8-Dibromo-5-hydr­oxy-4-oxo-2-phenyl-4H-chromen-7-yl acetate

In the title compound, C17H10Br2O5, the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C—H⋯O inter­actions and an intramolecular O—H⋯O hydrogen bond also occurs

5,7-Dimeth­oxy-2-phenyl-4H-chromen-4-one

The asymmetric unit of the title compound, C17H14O4, contains two independent mol­ecules which differ in the relative orientations of the phenyl rings with repect to the essentially planar [maximum deviations of 0.029 (2) and 0.050 (2) Å in the two mol­ecules] chromene fused-ring system, forming dihedral angles of 10.3 (5) and 30.86 (5)° in the two mol­ecules. The crystal structure is stabilized by weak C—H⋯O and C—-H⋯π inter­actions, and π–π stacking inter­actions

5,7-Bis(benz­yloxy)-2-phenyl-4H-chromen-4-one

In the title compound, C29H22O4, the chromene ring is almost planar with a small puckering [0.143 (2) Å]. The crystal structure is stabilized by C—H⋯O and C—H⋯π inter­actions. Edge-to-face (centroid–centroid distances of 3.894 and 3.673 Å) and face-to-face (centroid–centroid distance of 3.460 Å) π–π-ring electron inter­actions are also observed

Dimethyl 2,2′-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate: a more densely packed polymorph

The title mol­ecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o314–o315]. The mol­ecules of both polymorphs differ by the conformation of the oxomethyl­acetate groups. The title mol­ecules are rather planar compared to the mol­ecules of the other polymorph. In the title mol­ecule, one of the oxomethyl­acetate groups is disordered (occupancies of 0.6058/0.3942). The structures of both polymorphs are stabilized by C—H⋯O and C—H⋯π inter­actions. Due to the planarity of the title mol­ecules and similar inter­molecular inter­actions, the title mol­ecules are more densely packed than those of the other polymorph

2,6,6-Trimethyl­cyclo­hexene-1-carbaldehyde oxime

In the crystal of the title compound C10H17NO, synthesized by the reaction of β-cyclo­citral with hydroxyl­amine hydro­chloride, inversion-related mol­ecules are linked by a pair of O—H⋯N hydrogen-bonding inter­actions between the oxime functionalities, forming R 2 2(6) loops. The molecular conformation is stabilized by intra­molecular methyl C—H⋯N inter­actions. The cyclohexene ring has the typical half-chair conformation

4-Meth­oxy-5-[4-(4-meth­oxy-1,3-benzodioxol-5-yl)perhydro-1H,3H-furo[3,4-c]furan-1-yl]-1,3-benzodioxole

The 1,3-benzodioxole ring systems in the title compound, C22H22O8, are almost planar. The perhydro­furofuranyl system linking them adopts a distorted double-envelope conformation. Supra­molecular aggregation is effected by C—H⋯O, C—H⋯π and π–π [centroid–centroid distance of 3.755 Å, inter­planar distance of 3.633 Å and dihedral angle of 14.6°] inter­actions

2,6,6-Trimethyl­cyclo­hex-2-ene­carb­oxy­lic acid

In the title crystal structure, C10H16O2, inversion-related mol­ecules are linked by pairs of O—H⋯O hydrogen bonds involving carboxyl groups to form R 2 2(8) dimers. The cyclo­hexene ring displays a half-chair conformation

STUDIES ON THE INHIBITIVE EFFECT OF 3-HYDROXYFLAVONE ON THE ACID CORROSION OF MILD STEEL

The corrosion inhibition effect of 3-hydroxyflavone was studied on mild steel in 1 M hydrochloric acid (HCl). The anticorrosive effect was evaluated by weight loss and electrochemical methods which include Tafel polarization and AC impedance studies at 300 K. In weight loss method, the inhibition efficiency increased with increase in inhibitor concentration, and decreased with increase in temperature and immersion time, and acid concentration. The inhibitor showed maximum efficiency of 91% at 4 × 10-4 M concentration in 1 M hydrochloric acid. The Tafel polarization study showed that the inhibitor behaves likely as cathodic type. The corrosion inhibition effect measured by weight loss method and electrochemical studies was in good agreement with each other. The surface analysis was done by using scanning electron microscope (SEM). Several adsorption isotherms are assessed to study the adsorption behavior of the inhibitor on the mild steel surface. The negative value of ΔGads indicates the spontaneous adsorption of the inhibitor on mild steel surface.Adsorption isotherm, corrosion inhibition, electrochemical studies, 3-hydroxyflavone

2-Phenyl-5,7-bis(prop-2-en-1-yloxy)-4H-chromen-4-one

In the title compound, C21H18O4, tthe dihedral angle between the chromene ring system and the pendant phenyl ring is 6.1 (1)°. The crystal structure is stabilized by an intermolecular C—H...O and C—H...π interactions

2-Phenyl-5,7-bis(prop-2-en-1-yloxy)-4H-chromen-4-one

In the title compound, $C_{21}H_{18}O_4$, tthe dihedral angle between the chromene ring system and the pendant phenyl ring is $6.1 (1)^o$. The crystal structure is stabilized by an intermolecular $C—H \cdot \cdot \cdot O and C—H \cdot \cdot \cdot \pi interactions