Marsh reaction

Arsenic present only in traces (in any form) can be detected by reducing it to arsine and then applying tests for the latter. In Marsh s test, dilute sulphuric acid is added dropwise through a thistle funnel to some arsenic-free zinc in a flask hydrogen is evolved and led out of the flask by a horizontal delivery tube. The arsenic-containing compound is then added to the zinc-acid solution, and the delivery tube heated in the middle. If arsenic is present, it is reduced to arsine by the zinc-acid reaction, for example ... 

Although extraction of lipids from membranes can be induced in atomic force apparatus (Leckband et al., 1994) and biomembrane force probe (Evans et al., 1991) experiments, spontaneous dissociation of a lipid from a membrane occurs very rarely because it involves an energy barrier of about 20 kcal/mol (Cevc and Marsh, 1987). However, lipids are known to be extracted from membranes by various enzymes. One such enzyme is phospholipase A2 (PLA2), which complexes with membrane surfaces, destabilizes a phospholipid, extracts it from the membrane, and catalyzes the hydrolysis reaction of the srir2-acyl chain of the lipid, producing lysophospholipids and fatty acids (Slotboom et al., 1982 Dennis, 1983 Jain et al., 1995). SMD simulations were employed to investigate the extraction of a lipid molecule from a DLPE monolayer by human synovial PLA2 (see Eig. 6b), and to compare this process to the extraction of a lipid from a lipid monolayer into the aqueous phase (Stepaniants et al., 1997). 

Arsine, AsHs, is formed when many As-containing compounds are reduced with nascent hydrogen and its decomposition on a heated glass surface to form a metallic mirror formed the basis of Marsh s test for the element. The low-temperature reduction of AsCls with LiAlH4 in diethyl ether solution gives good yields of the gas as does the dilute acid hydrolysis of many arsenides of electropositive elements (Na, Mg, Zn, etc.). Similar reactions yield stibine, e.g. ... 

Much of the information available on resistance of nickel-iron alloys to corrosion by mineral acids is summarised by Marsh. In general, corrosion rates decrease sharply as the nickel content is increased from 0 to 30-40%, with little further improvement above this level. The value of the nickel addition is most pronounced in conditions where hydrogen evolution is the major cathodic reaction, i.e. under conditions of low aeration and agitation. Results reported by Hatfield show that the rates of attack of Fe-25Ni alloy in sulphuric and hydrochloric acid solutions, although much lower than those of mild steel, are still appreciable (Tables 3.35 and 3.36). In solutions of nitric acid, nickel-iron alloys show very high rates of corrosion. 

Sulfides and disulfides can be produced by bacterial reactions in the marine environment. 2-Dimeth-ylthiopropionic acid is produced by algae and by the marsh grass Spartina alternifolia, and may then be metabolized in sediment slurries under anoxic conditions to dimethyl sulfide (Kiene and Taylor 1988), and by aerobic bacteria to methyl sulfide (Taylor and Gilchrist 1991). Further details are given in Chapter 11, Part 2. Methyl sulfide can also be produced by biological methylation of sulfide itself (HS ). Carbon radicals are not the initial atmospheric products from organic sulfides and disulfides, and the reactions also provide an example in which the rates of reaction with nitrate... 

Microemulsion media seem to be very useful in getting monodisperse CaCOj particles of 30 A via carbonation of calcium phenates (Marsh, 1987) this process is relevant in making lube additives. The mechanism of reaction crystallization in such systems has hardly received attention. 

For the synthesis of D-glucuronic acid, methods of oxidation of suitable D-glucose derivatives have been devised during the past two decades these procedures have been comprehensively reviewed by Marsh,6 Mehltretter,7 and Heyns and Paulsen.8 For special purposes, for example, for the preparation of 6-I4C-labelled D-glucuronic acid, chain-extension reactions of 1,2-O-isopropylidene-a-D-xy/o-pen-todialdo-I,4-fiiranose by the cyanohydrin synthesis9 or by ethynyla-tion10 are used, but these frequently yield mixtures of D-glucuronic acid and L-iduronic acid. 

Using the results of Marsh and McLennan (see footnote 31), what percentage of the major accidents are due to runaway reactions ... 

Redox cycling of iron in salt marsh sediments. The solid lines and the dashed lines indicate redox reactions and precipitation reactions, respectively. 

E. H. P. Cordfunke, W. Ouweltjes. Solution Calorimetry for the Determination of Enthalpies of Reaction of Inorganic Substances at 298.15 K. In Experimental Thermodynamics, vol. 4 Solution Calorimetry K. N. Marsh, P. A. G. O Hare, Eds. Blackwell Scientific Publications Oxford, 1994 chapter 14. 

Cindy Lee is a Professor at the Marine Sciences Research Center of Stony Brook University. Dr. Lee s research examines the distribution and behavior of biogenic organic compounds, in particular the rates and mechanisms of transformation reactions occurring as these compounds undergo alteration. Her research investigates organic compounds in the sediments and waters of open ocean and coastal areas, salt marshes, lakes, as well as the atmosphere above these areas. Her expertise centers on the analytical techniques used to measure organic matter in the ocean. Dr. Lee is cur-... 

It is interesting to note that stratified combustible gas mixtures can exist in tunnel-like conditions. The condition in a coal mine tunnel is an excellent example. The marsh gas (methane) is lighter than air and accumulates at the ceiling. Thus a stratified air-methane mixture exists. Experiments have shown that under the conditions described the flame propagation rate is very much faster than the stoichiometric laminar flame speed. In laboratory experiments simulating the mine-like conditions the actual rates were found to be affected by the laboratory simulated tunnel length and depth. In effect, the expansion of the reaction products of these type laboratory experiments drives the flame front developed. The overall effect is similar in context to the soap bubble type flame experiments discussed in Section C5c. In the soap bubble flame experiment measurements, the ambient condition is about 300 K and the stoichiometric flame temperature of the flame products for most hydrocarbon fuels... 

Cellulosic fibers (cotton, rayon) are crosslinked by reaction of the hydroxyl groups of cellulose with formaldehyde, diepoxides, diisocyanates, and various methylol compounds such as urea-formaldehyde prepolymers, /V, /V -di tnethylol-A(A -dimethy lene urea, and trimethyl-olmelamine [Marsh, 1966]. Crosslinking imparts crease and wrinkle resistance and results in iron-free fabrics. 

Penkett, S. A, N. J. Blake, P. Lightman, A. R. W. Marsh, P. Anwyl, and G. Butcher, The Seasonal Variation of Nonmethane Hydrocarbons in the Free Troposphere over the North Atlantic Ocean Possible Evidence for Extensive Reaction of Hydrocarbons with the Nitrate Radical, J. Geophys. Res., 98, 2865-2885 (1993). 

Tbeae reactions are tbe analogues, in the dyad series, of the one by which marsh>gas is obtained from ao o acid. The hydrides of the dyad radicals so obtained are isomeric with those of the corresponding monad radicals,... 

Arsenic compounds may be detected easily by the Marsh test. In this test, some metallic zinc is added to an acid solution of the material to be tested, and the mixture is heated. The arsenic is liberated as arsine, AsH3, which may be decomposed by heat to give an "arsenic mirror." The reaction is... 

Using the 2138-A line of a zinc arc, Marsh and Heicklen296 photolyzed CFC13 in the presence of NO. Beside C1NO, they found infrared product bands at 6.19 and 8.8 [v. which they attributed to CFCl2NO, a stable product in their system. The indicated reaction was... 

J. Marsh, Advanced Organic Chemistry Reactions, Mechanism and Structure , McGraw-Hill, New York, 1968, p. 417 T. Tsuda, M. Miwa and T. Saegusa, J. Org. Chem, 1979, 3734. 

Combination of amines and dendrimers functionalized proton scavenger resins efficiently removes excess reagents from amide-formation reactions. Marsh et al.41 used a supported branched polyamine and... 

Waste dumps have vegetable matter. The vegetable matter in the waste dumps is decomposed in wet conditions by the action of bacteria present deep inside the dumps. As a result methane is formed. This reaction produces heat. Methane gas catches fire. For this reason, methane is also called marsh gas. 

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