The boedeker reaction—I

An enhanced gas sensor based on SiO2@mesoporous MCM-41 core-shell nanocomposites for SO2 visual detection

A colorimetric sulfur dioxide (SO₂) gas sensor based on a core-shell composite was developed. The composite was fabricated with a silicon dioxide core and a mesoporous MCM-41 shell (SiO₂@MCM-41), and further loaded with a mixture of zinc chloride (ZnCl₂), sodium nitroprusside (SNP) and hexamine as an SO₂ indicator. The sensing properties of SiO₂@MCM-41 toward SO₂ were measured in solid powder, discs and a gas detection tube (GDT), respectively. Each of these sensing configurations showed a distinct color change from pale yellow to red, which indicates good potential for naked-eye detection of SO₂. The limit of detection (LOD) is 2 ppm for SiO₂@MCM-41 discs, which indicates high sensitivity to SO₂. The performance of GDT suggested a linear relationship between the SO₂ concentration and the response length of the red portions in a range of 100-1000 ppm. This work shows promising potential of SiO₂@MCM-41 as an easy, effective and rapid response sensing material for the in situ detection of SO₂.

Light-activated generation of nitric oxide (NO) and sulfite anion radicals (SO3˙−) from a ruthenium(ii) nitrosylsulphito complex

This manuscript describes the preparation of a new Ru(ii) nitrosylsulphito complex,trans-[Ru(NH₃)₄(isn)(N(O)SO₃)]⁺(complex1), its spectroscopic and structural characterization, photochemistry, and thermal reactivity.

Stabilization by ethylenediaminetetraacetic acid of amide and other groups in drug compounds

Ethylenediaminetetraacetic acid (EDTA) was shown to be effective in stabilizing pharmaceutical compounds, which contain acetamido groups, from degradation by light, e.g. paracetamol. Its addition is particularly effective in stabilizing such compounds from the action of ascorbic acid in the light or dark. EDTA was also shown to stabilize lignocaine, sulphadiazine and succinylsulphathiazole. Previous studies had shown that EDTA stabilizes the acetamido group present in two synthetic food colouring compounds.

Specific cation effect in the reaction of nitroprusside with cysteine, acetophenone and sulfite (Legal and Boedeker reaction)

The colour formation of cysteine (I), acetophenone (II) and sulfite (III) with the sodium and tetrabutylammonium (TBA) salt of nitroprusside (NP2-) in aqueous solution was studied. The intensity of colour formation depends strongly on the nature and concentration of the cations and increases in the order TBA less than Li less than Na less than K less than Rb less than Cs (in case of cysteine TBA and Li are interchanged). This specific cation effect was known for the Boedeker reaction (III) and is now also demonstrated for the Legal reaction (I and II). The adduct formation between NP2- and I to III is based on an anion-anion interaction. The role of the cation is to reduce the Coulombic repulsion between the reactants by ion-pair formation. The efficiency of ion-pair formation corresponds with the order given before except for TBA, which behaves divergently.

Nitroprusside, antihypertensive drug and analytical reagent. Review of (photo)stability, pharmacology and analytical properties

A review of physical, chemical, analytical and pharmacological properties of nitroprusside is presented. In view of the pharmaceutical applications of nitroprusside special attention is given to the discussion of the (photo)degradation, the stability of the pharmaceutical formulations, the application as a reagent in pharmaceutical analysis and the redox behaviour.