86954-34-9

Basic information

• Product Name: neptunium
• Synonyms: 237Np;Neptunium-237;Neptunium, isotope of mass 237 (237np5+)
• CAS NO: 86954-34-9
• Molecular Formula: Np
• Mol File: 86954-34-9.mol

Chemical Properties

• Appearance: /
• CAS DataBase Reference: neptunium(CAS DataBase Reference)
• NIST Chemistry Reference: neptunium(86954-34-9)
• EPA Substance Registry System: neptunium(86954-34-9)

Safety Data

• Hazardous Substances Data: 86954-34-9(Hazardous Substances Data)

Upstream product

• 3352-57-6 hydroxyl 
• 15740-92-8 {Fe(4,4'-dimethyl-2,2'-bipyridine)3}(ClO4)2 
• 15388-48-4 tris(2,2'-bipyridyl)iron(II) perchlorate 
• 14586-54-0 tris(1,10-phenanthroline)iron(II) perchlorate 
• 1310-73-2 sodium hydroxide 
• 58670-16-9 (237)neptunium dioxide 

Relevant articles and documents

Reaction of Np(VI) with H2O2 in carbonate solutions

The kinetics and stoichiometry of the reaction of Np(VI) with H 2O2 in carbonate solutions were studied by spectrophotometry. In the range 1-0.02 M Na2CO3, the reaction 2Np(VI) + H2O2 = 2Np(V) + O2 occurs, as δ[Np(VI)]/δ[H2O2] ≈ 2. In Na 2CO3 + NaHCO3 solutions, the stoichiometric coefficient decreases, which is caused by side reactions. The reduction at low (1 mM) concentrations of Np(VI) and H2O2 follows the first-order rate law with respect to Np(VI), which suggests the formation of a Np(VI) peroxide-carbonate complex, followed by intramolecular charge transfer. Addition of Np(V) in advance decreases the reaction rate. An increase in the H2O2 concentration leads to the reaction deceleration owing to formation of a complex with two peroxy groups. In a 1 M Na 2CO3 solution containing 1 mM H2O2, the first-order rate constant k increases with a decrease in [Np(VI)] from 2 to 0.1 mM. For solutions with [Np(VI)] = [H2O2] = 1 mM, k passes through a minimum at [Na2CO3] = 0.5-0.1 M. The activation energy in a 0.5 M Na2CO3 solution is 48 kJ mol-1. Pleiades Publishing, Inc., 2010.

Reduction of Np(VI) with Carbohydrazide in a Perchloric Acid Solution

The stoichiometry of the reaction of Np(VI) with carbohydrazide (NH2NH)2CO in a 0.02 M HClO4 solution was studied by spectrophotometry. With Np(VI) taken in excess, 1 mol of carbohydrazide reduces 5 mol of Np(VI) to Np(V). In 0.1?2.0 M HClO4 solutions (the ionic strength of 2.0 was supported by adding LiClO4) containing 3–100 mM (NH2NH)2CO, Np(VI) at a concentration of 1 mM at 20-45°С is consumed in accordance with a first-order rate law until less than 0.2 mM Np(VI) remains. Then the reaction decelerates. The reaction is first-order with respect to carbohydrazide and has the order of ?1.45 with respect to Н+ ions. The activated complex is formed with the loss of 1 and 2 Н+ ions. The activation energy is 86 ± 5 kJ mol?1.

Reduction of Np(VI) with Hexamethylenetetraacetic Acid in HClO4 Solution

Abstract: Spectroscopic method was used to examine the stoichiometry of the reaction of No(VI) with hexamethylenediaminetetraacetic acid (HMDTA, H4hmdta) in a 0.05 M HClO4 solution. At an excess of Np(VI), 1 mole of complexon reduces about 4 moles of Np(VI) to Np(V). In 0.1–1.0 M HClO4 solutions (the ionic strength of 1.0 was maintained with LiClO4) containing 2–20 mM HMDTA, neptunium(VI) with concentration of 0.3–3.0 M decreases at 35–55°C by the first-order rate law until the instant when less than 20% Np(VI) remains. The initial reaction rate has the first order in [HMDTA] and –2 order in [H+]. An activated complex is formed with loss of two H+ ions. The activation energy is 102 ± 7 kJ/mol.

Reaction of Np(VI) with cyclohexanediaminetetraacetic acid in HClO4 solutions

The stoichiometry of the reaction of Np(VI) with cis-cyclohexanediaminetetraacetic acid (CHDTA, H4chdta) in 0.05 M HClO4 solution was studied by spectrophotometry. With Np(VI) in excess, 1 mol of the complexone converts 4 mol of Np(VI) into Np(V). In 0.115–0.98 M HClO4 solutions (the ionic strength of 1.0 was supported with LiClO4) containing 3–29 mM CHDTA at 20–45°С, Np(VI) at a concentration of 0.2–3.3 mM is consumed in accordance with the first-order rate law until less than 40% of Np(VI) remains. After that, the reaction decelerates. The reaction rate has first order with respect to [CHDTA] and the order of–1.2 with respect to [H+]. The activated complex is formed with the loss of one and two Н+ ions. The activation energy is 82.3 ± 3.8 kJ mol–1.

Catalytic reduction of Np(VI) with formic acid in the presence of platinum nanoparticles

The kinetics of catalytic reduction of Np(VI) with formic acid in the presence of Pt nanoparticles of different types ( brown colloid stabilized with sodium polyacrylate and nonstabilized gray colloid) was studied. In both cases in the examined range of conditions ([Np(VI)] 0 = 2.80 × 10-4-9.03 × 10-4 M; [HCOOH] = 0.03-1.0 M; [Pt] = 4 × 10-7-2 × 10-5 M; T = 18-60°C) the reaction is zero-order with respect to [Np(VI)] and first-order with respect to [HCOOH]. The catalytic activity of the nonstabilized gray colloid exceeds by almost an order of magnitude that of the brown colloid, due to the blocking effect of stabilizing polyelectrolyte molecules on the active catalytic centers. The dependence of the reaction rate on the sodium polyacrylate concentration in the range 1 × 10-4-1 × 10-2 M is nonmonotonic, due to deflocculation of the nanoparticles. The mechanism of the catalytic reduction of Np(VI) with formic acid in the presence of Pt colloids is discussed; it involves a slow step of dissociative chemisorption of HCOOH molecules on the nanoparticle surface. Pleiades Publishing, Inc., 2006.

Kinetics and mechanism of Np(IV) oxidation with nitric acid

Neptunium (IV) is oxidized to Np(V) with nitric acid in the presence of U(VI) under conditions of low acidity (1[Np(IV)]/[H +]2 + k 2[Np(I

Sorption of neptunium in the highest oxidation states from alkaline solutions with complexing fibrous "filled" sorbents

Sorption of Np(VII), Np(VI), and Np(V) from 1 M NaOH by complexing fibrous "filled" sorbents was examined. POLIORGS 33-n and 34-n sorbents containing amidoxime and hydrazidine groups efficiently recover Np in the highest oxidation states and exhibit good

Kinetics of neptunium(VI) reduction by kojic acid

The kinetics for Np(VI) reduction by kojic acid, HK, have been studied at tracer level concentrations of Np(VI) in aqueous chloride media. The empirical rate expression for the reaction was found to be -d[Np(VI)]/dt = k[Np(VI)][HK]T/[H+], where T denotes the total concentration. Rate constant and activation parameters have been determined at an ionic strength of 1.0 M (NaCl) and 25.0°C to be k = 1.63 ± 0.08 s-1, ΔH? = 82.7 ± 3.4 kJ/mol, and ΔS? = 34 ± 12 J/(mol·K). The rate decreases with increasing ionic strength. A reaction mechanism is discussed.

Electron transfer between neptunium(VI) and substituted 1,10-phenanthroline and 2,2′-bipyridine complexes of iron(II)

The kinetics of electron transfer between Np(VI) and some complexes of iron(II) with phenanthroline-like ligands have been investigated by means of a stopped-flow spectrophotometric technique. The rate constants and the related activation parameters have been discussed in the light of the Marcus theory for outer-sphere electron transfers.