Heavy-metal free

A similar situation pertains in the PVC stabiliser sector, where environmental restrictions have acted as an incentive to PVC reformulation (replacement of the commonly used liquid and solid Ba/Cd and solid Pb stabiliser systems). Producers of heat stabilisers for PVC nowadays strive to create products that are heavy-metal-free and provide strong weatherability and... 

Stid-Chemie, Application Note Sorbacid , Heavy Metal Free PVC Stabilisation, Stid-Chemie AG, Moosburg, Germany (2001). 

In this context, Czekelius and Carreira have recently documented a convenient heavy-metal-free transformation of optically active nitroalkanes 12 to chiral aldoximes 13 at room temperature by employing inexpensive reagents benzyl bromide, KOH and 5 mol% n-BU4NI (Scheme 14). This provides an environmentally friendly reaction that excludes the potential contamination of the products by metal impurities. 

Despite the unique synthetic possibilities offered by organotin reagents, their use in the chemical industry has steadily declined in recent years as a result of perceived toxicity and environmental concerns associated with disposal of tin wastes.30-31 Consequently, appreciable efforts have been made to develop heavy metal-free alternatives based on silicon, germanium, or phosphorus chemistry. Other strategies have been applied to immobilize the tin reagents or to reduce their usage to less than stoichiometric amounts. 

FIGURE 27.6 Heavy metal-free chiral-reducing agents based on Ge and Si chemistry. 

In early days Alfred Nobel already replaced mercury fulminate (MF, see above), which he had introduced into blasting caps, with the safer to handle primary explosives lead azide (LA) and lead styphnate (LS) (Fig. 1.17). However, the long-term use of LA and LS has caused considerable lead contamination in military training grounds which has stimulated world-wide activities in the search for replacements that are heavy-metal free. In 2006 Huynh und Hiskey published a paper proposing iron and copper complexes of the type [cat]2[Mn(NT)4(H20)2] ([cat]+ = NH4, Na+ M = Fe, Cu NT = 5-nitrotetrazolate) as environmentally friendly, green primary explosives (Fig. 1.17) [3]. 

It is therefore desirable, to find suitable heavy metal-free replacements for both lead azide and lead styphnate. Current research is addressing this problem. The following replacements in stab detonators are presently being researched ... 

Barium (heavy metal) free green illuminants,... 

Iselin, N.J., llth-12th Sept.2001, p.97-101 NON-LEAD AND HEAVY METAL-FREE TRENDS IN WIRE AND CABLE Grant J... 

Non-lead and heavy-metal-free (HMF) stabilised PVC compounds present a viable material alternative to vinyl lead-based systems for wire and cable applications. Trends driving the use of these non-lead and HMF materials in... 

A new polymer-bound reagent system for the efficient oxidation of primary alcohols to aldehydes and of secondary alcohols to ketones in the presence of a catalytic amount of 2,2,6,6-tetramethyl-l-piperidonoxyl (TEMPO) has been described [102]. Work-up of this heavy metal free oxidation is achieved by simple filtration followed by removal of the solvent. Benzyl alcohol was oxidized in 94% yield. The more demanding cyclohexyl alcohol was converted into cyclohexanone in 96 % yield. 

Instead of using cadmium, tin and lead, these stabilizer products present a nontoxic, haze-free, phenol free, heavy-metal-free alternative (Table 17). 

Hydrotalcite, Mg6Al2(OH) 16CO34H2O, a synthetic clay mineral with a layered structure of hexagonal platelets, acts as HCl scavengers in PVC stabilization [141]. Together with mixed-metal Ca/Zn systems hydrotalcite constitutes an environmentally friendly, non-toxic, heavy-metal free method of PVC stabilization in flexible, rigid and transparent PVC applications [142]. 

Convective redistribution of water vapor, sulfates, nitrates, soot, carbon, heavy metals free-radical catalysis and associated photochemical mechanisms... 

Whereas, in order to achieve a high level of environmental protection, the marketing of certain batteries should be prohibited, in view of the amount of mercury they contain whereas that prohibition, in order to achieve its full effect for the environment, must cover appliances into which such batteries and accumulators are incorporated whereas such prohibition may have a positive impact in facilitating the recovery of batteries Whereas the technical development of alternative heavy-metal-free batteries should be taken into account ... 

The plastic industry continues to move away from toxic colorants, especially those based on heavy metals such as chromium, cadmium, and lead. In the U.S., at least 18 states ban the use of heavy metals, including colorants, in packaging materials. The European Union and some other countries have restrictions on their use, as well. The use of organic colorants or heavy-metal-free (HMF) colorants is continuously increasing, and many colorant producer companies are replacing all of their heavy-metal-containing colorants with systems that present fewer environmental problems and legal restrictions. Colorants incorporated in plastic containers in direct contact with food have to be cleared by FDA, as is the case for other additives. 

A convenient procedure for the aminobromination of electron-deficient olefins 90 using Bromamine-T (TsNBrNa) as nitrogen and bromine source promoted by (diacetoxyiodo)benzene has been developed [96]. This heavy-metal-free protocol is highly efficient and affords the vicinal bromamines 91 with excellent regio-and stereoselectivities (Scheme 3.35). 

Biron M. Fashionable and inevitable free in every way halogen free, lead and other heavy metal free, VOC free... industry web report (www.specialchem4 polymers.com). SpecialChem S.A. 2008 (downloaded 14 August 2008). 

Features Chem. resist. fluorescent heat stable heavy metal-free It. stable... 

Features Fluorescent heat stable heavy metal-free It. stable Properties Paste m.w. 4800 hyd. no. 35 100% solids PDI Type 46 [Ferro/Plastic Colorants]... 

Features Highly effective heavy metal-free replacement for toxic anticorrosive pigments such as red lead, zinc chromate, strontium chromate alternative for heavy metal-contg. zinc phosphate-based pigments Toxicology Nontoxic Sibrid TC [Gelest]... 

All assays were performed under heavy-metal free conditions after extraction of heavy-metals and the acid treatment of glassware to remove contaminating heavy-metal ions. Except where stated otherwise, assays were carried out spectrophotometrically at 340 nm and SO C in a 1 ml reaction mixture containing 50 mM Tris, pH 7.8, 0.14 mM NADH, 0.1 p,g PGK and 40 p.g glyceraldehyde-phosphate dehydrogenase. Concentrations of free Mg2+, MgATp2-, and PGA were calculated as described previously (11). 

The move away from lead has inspired intensive development work to produce new heavy metal-free organic stabilisers and improve the existing alternatives, notably calcium-zinc. A stabilised PVC formulation must withstand being heated and subjected to mechanical shear at the same time, because heat-induced decomposition can induce some crosslinking, increasing... 

There has been a big effort to develop different approaches to stabilisation that make more use of organic substances and completely avoid heavy metals. Many of these products were originally aimed at the pipe industry. The recent changes in Emopean legislation relating to the permissible levels of lead in water have focused attention on PVC potable water pipes. Crompton Vinyl Additives GmbH markets heavy metal-free (organic based stabilisers)... 

Reed Lite, Heavy-metal free-standard concentrates, Clariant, ReedSpectrum... 

A range of encapsulated heavy-metal-free single-pigment dispersions and custom colour matches that can be added at any point in the compounding process, developed by Holland Colors under the name Engineering Holcobatch, is claimed to improve the properties of filled (mainly glass-filled) plastics. 

They began working with people around the world Romanian farmers who dew- or field-ret hemp stalks a Japanese mill owner committed to green processes, even new methods such as using ozone to bleach fabric a 100-year-old Italian mill that produces no wastewater a Chilean mill shifting to entirely green processes an Italian dye house that produces biodegradable, heavy metal free textiles. 

---