Active sulphate

While well-aerated near-neutral waters are normally much more corrosive than poorly-aerated waters, waters with near zero oxygen contents may cause high rates of corrosion if active sulphate-reducing bacteria, which can act as very efficient depolarising agents, are present. A corrosion rate of 1 5 mm/y has been observed on cast iron exposed to such a water. 

The presence of active sulphate-reducing bacteria usually results in graphitic corrosion and this has led to a useful method of diagnosing this cause of corrosion. The leaching out of iron from the graphitic residue which is responsible for the characteristic appearance of this type of corrosion leads to an enriched carbon, silicon and phosphorus content in the residue as compared with the original content of these elements in the cast iron. Sulphur is usually lost to some extent but when active sulphate-reducing bacteria are present, this loss is offset by the accumulation of ferrous sulphide in the residue with a consequent increase in the sulphur content of the residue out... 

Table 3.44 Increase in sulphur content of graphitic corrosion residue due to the presence of active sulphate-reducing bacteria...

The most widely accepted criterion for protection of steel at room temperature (the protection potential) in aerobic conditions is - 0 - 85 V with respect to a Cu/CuSOa reference electrode. In anaerobic conditions -0-95 V (vs. Cu/CuSOa) is the preferred protection potential because of the possible presence of active sulphate-reducing bacteria (SRB). 

Soil supporting active sulphate-reducing bacteria 451-9... 

R9. Robbins, P. W., and Lipmann, F., Identification of enzymatically active sulphate as adenosine-3 -phosphate-5 -phosphosulphate. J. Amer. Chem. Sac. 78, 2652-2653 (1956). 

The volatilized nitrogen oxides can be used in the HNO3 synthesis and then to the calcium nitrate production, therefore the process will form closed circnit. However, the belite thus produced revealed poor hydrauhc properties and, as a next step, 6% of gypsum was added to the mixture. As a result, the very active sulphate belite was obtained, particularly when the spongiolite was used as a source of silica, instead of quartz. The authors foimd the substitution of silicon by sulphur with the formation of solid solution with the formula... 

The classical depolarization theory is highly disputed due to the fact that only hydrogenase-active sulphate reducers would be able to increase corrosion rates under anaerobic conditions. However, several studies demonstrated that also the presence of sulphate-reducing bacteria possessing no hydrogenase significantly... 

Voogt [4], as long ago as 1959, used a three-column apparatus to separate anionics, soaps, cationics and nonionics. This system is still in use. The first column contained a strongly acidic cation exchanger as the free sulphonic acid. This retained cationics and converted all anions to the corresponding acids. The second column contained a strongly basic anion exchanger acetate, to retain all surface-active sulphates and sulphonates. The third column contained the same resin as the hydroxide, to retain the fatty acids. The effluent contained the nonionics. The sorbed surfactants could all be recovered by elution with hydrochloric acid. 

Just as in the case of N, the source of the sulphur of higher plants is an oxidized form, namely sulphate. And just like nitrate, sulphate must first be reduced. Ultimately, sulphur is present in the doubly negative form as S. The first step in the assimilation of S is the fixation of sulphate. This is brought about by sulphate reacting with ATP to liberate pyrophosphate. An adenosine-phosphate-sulphate compound is formed and to the ribose of this compound another phosphate residue from another ATP molecule is attached. The product thus obtained is 3 -phosphoryl-5 -adenosine-phosphoryl-sulphate or simply active sulphate (Fig. 114). In this way sulphur is fixed and activated. It is this bound form of active sulphate which is subjected to reduction to the level of S. It is likely that 2 electron transitions are also implicated here. The mechanism is still unknown. 

Toluene, due to its high reactivity in HF/BF3/CO formylation reactions was initially used as formylation substrate with un-activated sulphated zirconiumoxide as acid catalyst. No reaction occurred even after extended reaction times and increased temperatures (Table 2.5, Run 1 and 2). 

Hoshino, T, Hayashi, T, Hayashi, K, Hamada, J., Lee, J.B., and Sankawa, U. (1999) An antivirally active sulphated polysaccharide from Sargassum homeri. Biol. Pharm. Bull., 21, 730-734. 

Plants obtain their sulphur as sulphate ions (valency +6) from the soil and the assimilation of sulphate involves its reduction to the level of sulphide (valency —2). Early studies on sulphate utilisation using homogenates of mammalian liver indicated that formation of phenyl sulphates depended on the presence of ATP and involved the intermediate formation of active sulphate , an adenosine phospha-tosulphate analagous to active acetate (see p. 98). The activated sulphate group can be transferred to a variety of acceptors such as the phenols mentioned above or can be reduced as occurs in those organisms which use sulphate as their source of sulphur. 

The reactions leading to the formation of active sulphate were elucidated in enzyme fractionation studies on baker s yeast. It is a two-step process leading first to the formation of adenosine-5 -phosphosulphate (APS) and then to the active sulphate , 3 -adeno-sine-5 -phosphosulphate (PAPS) thus ... 

It should be noted that the aqueous extract of the turnips shows weak peroxidase activity before precipitation with ammonium sulphate. 

The experimental conditions for conducting the above reaction in the presence of dimethylformamide as a solvent are as follows. In a 250 ml. three-necked flask, equipped with a reflux condenser and a tantalum wire Hershberg-type stirrer, place 20 g. of o-chloronitrobenzene and 100 ml. of diinethylform-amide (dried over anhydrous calcium sulphate). Heat the solution to reflux and add 20 g. of activated copper bronze in one portion. Heat under reflux for 4 hours, add another 20 g. portion of copper powder, and continue refluxing for a second 4-hour period. Allow to cool, pour the reaction mixture into 2 litres of water, and filter with suction. Extract the solids with three 200 ml. portions of boiling ethanol alternatively, use 300 ml. of ethanol in a Soxhlet apparatus. Isolate the 2 2- dinitrodiphenyl from the alcoholic extracts as described above the 3ueld of product, m.p. 124-125°, is 11 - 5 g. 

Phthalide. In a 1 litre bolt-head flask stir 90 g. of a high quality zinc powder to a thick paste with a solution of 0 5 g. of crystallised copper sulphate in 20 ml. of water (this serves to activate the zinc), and then add 165 ml. of 20 per cent, sodium hydroxide solution. Cool the flask in an ice bath to 5°, stir the contents mechanically, and add 73-5 g. of phthalimide in small portions at such a rate that the temperature does not rise above 8° (about 30 minutes are required for the addition). Continue the stirring for half an hour, dilute with 200 ml. of water, warm on a water bath imtil the evolution of ammonia ceases (about 3 hours), and concentrate to a volume of about 200 ml. by distillation vmder reduced pressure (tig. 11,37, 1). Filter, and render the flltrate acid to Congo red paper with concentrated hydrochloric acid (about 75 ml. are required). Much of the phthalide separates as an oil, but, in order to complete the lactonisation of the hydroxymethylbenzoic acid, boil for an hour transfer while hot to a beaker. The oil solidifles on cooling to a hard red-brown cake. Leave overnight in an ice chest or refrigerator, and than filter at the pump. The crude phthalide contains much sodium chloride. RecrystaUise it in 10 g. portions from 750 ml. of water use the mother liquor from the first crop for the recrystaUisation of the subsequent portion. Filter each portion while hot, cool in ice below 5°, filter and wash with small quantities of ice-cold water. Dry in the air upon filter paper. The yield of phthalide (transparent plates), m.p. 72-73°, is 47 g. 

Procedures of the beta-galactosidase activity measuring using colour reaction with ONPG and X-Gal without cells permeabilization were developed and the detection limit at the level of 4 ppb has been achieved. The influence of the foreign ions (phosphate, sulphate, carbonate et. al) was studied. 

NaCl, interact with the sulphur and vanadium oxides emitted from the combustion of technical grade hydrocarbons and die salt spray to form Na2S04 and NaV03- These conosive agents function in two modes, either the acidic mode in which for example, the sulphate has a high SO3 thermodynamic activity, of in the basic mode when the SO3 partial pressure is low in the combustion products. The mechanism of coiTosion is similar to the hot coiTosion of materials by gases widr the added effects due to the penetration of tire oxide coating by tire molten salt. 

A comparison of the activities of these three alkaloids lias been made by Graliam and Gunn using their antagonism to the effects of carbamjd-choline chloride on isolated mammalian intestine. The relative activities found were, atropine sulphate 1 I-hyoscyamine sulphate 2-4 hyoscine hydro bromide 1-5. The results of previous authors are discussed and reasons suggested for some of the differences found. 

The process of isolation finally adopted by the former authors consists in precipitating as reineckates the water-soluble bases contained in a methyl alcoholic extract of the curare. The mixed reineckates are further purified, by solution in acetone and precipitation with water as often as may be necessary. The product so cleaned represents the bulk of the biological activity of the crude drug the mother liquors may contain curine (p. 374), which indicates a menisperm as one of the components of such curares. The mixed reineckates are then fractionated chromato-graphically over alumina and the components isolated as chlorides by the use of silver sulphate and barium chloride in succession. This process has been modified in detail by Schmid and Karrer, who have also found that with their curare, the more soluble reineckate fraction includes less potent quaternary alkaloids. 

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