Molybdenum orange

Synonym(s) Chromic acid, lead and molybdenum salt lead chromate, sulphate and molybdate molybdenum-lead chromate molybdenum orange Lead dinitrate nitric acid lead(2+) salt lead (II) nitrate plumbous nitrate Lead(2+) oxide lead monoxide litharge massicot Lead(2+) phosphate Phosphoric acid lead(2+) salt ... 

Molybdenum orange is a solid solution of lead molybdate, lead chromate and often lead sulfate. It is used as a pigment in paints, plastics and printing inks. The pigment is used for red hues in automobile and appliance paints. 

Molybdenum orange is precipitated by adding solutions of sodium chromate, sodium molybdate, and sodium sulfate to a solution of lead nitrate. The solid mixture is filtered and the precipitate is slowly dried under controlled conditions. Molybdenum orange is obtained as a fine powder of dark orange or light red color. 

Molybdenum salts used as catalysts include cobalt molybdate for hydrogen treatment of petroleum stocks for desulfurization, and phospho-molybdates to promote oxidation. Compounds used for dyes are sodium, potassium, and ammonium molybdates. With basic dyes, phosphomolyb-dic acid is employed. The pigment known as molybdenum orange is a mixed crystal of lead chromate and lead molybdate. Sodium molybdate, or molybdic oxide, is added to fertilizers as a beneficial trace element. Zinc and calcium molybdate serve as inhibitory pigments in protective coatings arid paint for metals subjected to a corrosive atmosphere. Compounds used to produce better adherence of enamels are molybdenum trioxide and ammonium, sodium, calcium, barium, and lead molybdates. 

Lead chromate is almost insoluble and has very low bioavailability. Studies on lead chromate pigment have shown that it does not have the carcinogenic potential of soluble chromates, such as zinc chromate. As with other heavy metals, solubility is the key to toxicity. With proper safeguards such as adequate ventilation and personal protective equipment, chrome yellow and molybdenum orange can be safely used in the workplace. 

SYNS CHROMIC ACID, LEAD and MOLYBDENUM SALT CHROMIC ACID LEAD SALT with LEAD MOLYBDATE C.I. PIGMENT RED 104 LEAD CHROMATE, SULPHATE and MOLYBDATE MOLYBDENUM-LEAD CHROMATE MOLYBDENUM ORANGE... 

Molybdate orange and red are pigments (qv) that contain lead(II) molybdate [10190-33-3], PbMoO, formulated in mixed phases with PbCrO and PbSO. The mixed phase is more intensely colored than any of the component phases. Concerns about lead content are lessening the use of these materials (see also Paint). Various organic dyes are precipitated with heteropolymolybdates. This process allows the fixation of the dye in various fabrics. The molybdenum anion generally imparts light stabiHty to the colorant as weU (91). 

Molybdates yield sparingly soluble orange-yellow molybdyl oxinate with oxine solution the pH of the solution should be between the limits 3.3-7.6. The complex differs from other oxinates in being insoluble in organic solvents and in many concentrated inorganic acids. The freshly precipitated compound dissolves only in concentrated sulphuric acid and in hot solutions of caustic alkalis. This determination is of particular interest, as it allows a complete separation of molybdenum from rhenium. 

Rhenium, molybdenum and vanadium ions yield orange, pink and yellow-colored chromatogram zones respectively on a colorless background. 

Tricarbonyltris(pyridine)molybdenum(0) is a yellow to orange crystalline compound that can be handled in the ambient atmosphere without noticeable decomposition. It can be stored indefinitely at 0-5°C under an inert atmosphere. It decomposes at 205-210°C (a gradual change in color from yellow to brown is already observed starting at 100-105°C). Its IR spectrum shows two carbonyl bands at 1901 and 1764 cm. ... 

PDB ID 1 N2C) (a) In this ribbon diagram, the dinitrogenase subunits are shown in gray and pink, the dinitrogenase reductase subunits in blue and green. The bound ADP is red. Note the 4Fe-4S complex (Fe atoms orange, S atoms yellow) and the iron-molybdenum cofactor (Mo... 

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