Sulphur formation

Sulphur mineralisation Sulphur is ubiquitous in minerals at hydrothermal vents (e.g. native sulphur, metal sulphides, sulphates), and the formation of many of these minerals is potentially influenced by the associated microbial activity at vents. For example, microbial filamentous sulphur formation has recently been proposed as a widespread activity in mixed H2S-02 environments and may be a quantitatively important microbial process in hydrothermal vent... 

To test this prediction the surface of CuS membranes, dissolved anodically in the media discussed above, was analyzed for the presence of sulphur by using SEM/EDAX technique with sulphur probe. In 1 M HCl the sulphur presence can clearly be seen already after one anodic half-cycle (Fig. 10). In 1x10 M HCl no sulphur could be detected. In 1x10 M HCl + 1 M KCl the result of the analysis was not definite, the surface analyzed by XRD, however, provided the strong indication of sulphur presence, because of the characteristic low-angle spectrum. Fig.9. To facilitate sulphur formation under these conditions potentiostatic dissolution at +600 mV (SCE) for 72 h was attempted. The presence of sulphur was quite evident (Fig.ll) which is opposite to the observation of CuS membrane surface dissolved under the same conditions in lxlO M HCl, (Fig.5). Finally, the surface of CuS disc left in... 

Diamond is very resistant to chemical reagents potassium dichromate and sulphuric acid attack it with the formation of CO2. It burns in air or oxygen at 700 C to CO2 leaving scarcely any ash some forms of bort may leave as much as 4-5% ash. 

Lenk T J, Hallmark V M, Rabolt J F, Haussling L and Ringsdorf H 1993 Formation and characterization of self-assembled films of sulphur-derivatized poly(methyl methacrylates) on gold Macromolecules 26 1230-7... 

Strong oxidising acids, for example hot concentrated sulphuric acid and nitric acid, attack finely divided boron to give boric acid H3CO3. The metallic elements behave much as expected, the metal being oxidised whilst the acid is reduced. Bulk aluminium, however, is rendered passive by both dilute and concentrated nitric acid and no action occurs the passivity is due to the formation of an impervious oxide layer. Finely divided aluminium does dissolve slowly when heated in concentrated nitric acid. 

The second equilibrium is the more important, giving rise to the nitronium ion, NOj, already mentioned as a product of the dis sociation of dinitrogen tetroxide. Several nitronium salts have been identified, for example nitronium chlorate(VII), (N02) (C104) . If pure nitric acid is dissolved in concentrated sulphuric acid, the freezing point of the latter is depressed to an extent suggesting the formation of four ions, thus ... 

When sulphur is melted viscosity changes occur as the temperature is raised. These changes are due to the formation of long-chain polymers (in very pure sulphur, chains containing about 100 (X)0 atoms may be formed). The polymeric nature of molten sulphur can be recognised if molten sulphur is poured in a thin stream into cold water, when a plastic rubbery mass known as plastic sulphur is obtained. This is only slightly soluble in carbon disulphide, but on standing it loses its plasticity and reverts to the soluble rhombic form. If certain substances, for example iodine or oxides of arsenic, are incorporated into the plastic sulphur, the rubbery character can be preserved. 

Detergents are made by, for example, treating petroleum hydrocarbons with sulphuric acid, yielding sulphonated products which are water soluble. These can also solubilise fats and oils since, like the stearate ion, they have an oil-miscible hydrocarbon chain and a water-soluble ionic end. The calcium salts of these substances, however, are soiu u-ic in water and, therefore, remove hardness without scum formation. 

The formation of an insoluble film of barium sulphate soon causes the reaction to cease, but addition of a tittle hydrochloric acid or better phosphoric(V) acid to the sulphuric acid allows the reaction to continue. 

The formation of other polysulphuric acids H2S30io up to H2 0(S0j) , by the addition of more sulphur trioxide, have been reported. 

When concentrated sulphuric acid is added to ethanol, the mixture becomes hot owing to the formation of ethyl hydrogen sulphate, the yield of which is increased if the mixture is then gently boiled under reflux ... 

The mechanism of the formation of these three compounds is based on the initial reaction between ethanol and a strong acid such as sulphuric acid, which involves protonation of the ethanolic oxygen to form the ion (1). 

When a mixture of aniline, nitrobenzene, glycerol and concentrated sulphuric acid is heated, a vigorous reaction occurs with the formation of quinoline. It is probable that the sulphuric acid first dehydrates the glycerol giving acrolein or acraldehyde (A), which then condenses at its double bond with the amino group of the aniline to give acrolein-aniline (B), The latter in its enol... 

Dissolve ca. 0 2 g. of product (I) in cold ethanol, and add with shaking 1-2 drops of dilute sulphuric acid. A deep purple coloration appears at once. This shows that salt formation has occurred on the quinoline nitrogen atom to form the cation (Ha), which will form a resonance hybrid with the quinonoid form tils). [Note that the forms (IIa) and (11b) differ only in electron position, and they are not therefore tautomeric.] If, hoAvever, salt formation had occurred on the dimethylaniino group to give the cation (III), thrs charge separiition could not occur, and the deep colour would be absent. 

Now add more dilute sulphuric acid drop by drop the colour almost completely fades, as salt formation occurs on both nitrogen atoms with suppression of the resonance hybrid formation. 

To a cold aqueous solution of benzoquinone, add 1 drop of sulphurous acid solution (SOj-water) the solution turns deep green-brown owing to the intermediate formation of quinhydrone, CeH402,CeIl4(0H)2. Now add excess of sulphurous acid the solution becomes colourless owing to the formation of hydroquinone. Add a few drops of FeClj solution the reaction is reversed and the deep yellow colour (distinct from that of FeCl ) is restored. 

Removal of sulphur as sodium sulphide. Dissolve about 0 i g. of c> stine in a few ml. of 10% NaOH solution. Add a few drops of lead acetate solution and boil for 1 minute. The solution darkens owing to the formation of lead sulphide. 

Diethyl ether may be prepared from ethyl alcohol by the sulphuric acid process. A mixture of alcohol and sulphuric acid in equimolecular proportions is heated to about 140° and alcohol is run in at the rate at which the ether produced distils from the reaction mixture. Ethyl hydrogen sulphate (or ethyl sulphuric acid) is first formed and this yields ether either by reacting directly with a molecule of alcohol or by the formation and alcoholysis of diethyl sulphate (I) ... 

The above simple process cannot be applied to the preparation of the homo-logues a higher temperature is requir (di-n-amyl ether, for example, boils at 169°) and, under these conditions, alkene formation predominates, leading ultimately to carbonisation and the production of sulphur dioxide. If, however, the water is largely removed by means of a special device (see Fig. Ill, 57,1) as soon as it is formed, good 300 of ethers may be obtained from primary alcohols, for example ... 

If desired, the alcohol may be identified as the 3 5-dinitrobenzoate (Section 111,27) it is then best to repeat the experiment on a larger scale and to replace the dilute hydrochloric acid by dilute sulphuric acid. It must, however, be pointed out that the reaction is not always so simple as indicated in the above equation. Olefine formation and rearrangement of the alcohol sometimes occur thus n-prop3 lamine yields n-propyl alcohol, isopropyl alcohol and propylene. 

Mix 31 g. (29-5 ml.) of benzyl alcohol (Section IV, 123 and Section IV,200) and 45 g. (43 ml.) of glacial acetic acid in a 500 ml. round-bottomed flask introduce 1 ml. of concentrated sulphuric acid and a few fragments of porous pot. Attach a reflux condenser to the flask and boil the mixture gently for 9 hours. Pour the reaction mixture into about 200 ml. of water contained in a separatory funnel, add 10 ml. of carbon tetrachloride (to eliminate emulsion formation owing to the slight difference in density of the ester and water, compare Methyl Benzoate, Section IV,176) and shake. Separate the lower layer (solution of benzyl acetate in carbon tetrachloride) and discard the upper aqueous layer. Return the lower layer to the funnel, and wash it successively with water, concentrated sodium bicarbonate solution (until effervescence ceases) and water. Dry over 5 g. of anhydrous magnesium sulphate, and distil under normal pressure (Fig. II, 13, 2) with the aid of an air bath (Fig. II, 5, 3). Collect the benzyl acetate a (colourless liquid) at 213-215°. The yield is 16 g. 

The epoxides may be converted into 1 2-glycols by hydrolysis. In some cases the 1 2-glycol may be produced directly by carrying out the epoxidation in the presence of water. If the 1 2-glycol is desired, it is usually better to employ performic acid or peracetic acid, the latter best in the presence of a trace of sulphuric acid. An epoxide is first formed, followed by the hydroxy-formate or hydroxy-acetate, and ultimately the 1 2-glycol ... 

Girard s reagent P , C5H5NCH2C0NHNH2 C1. In a 1-htre threenecked flask, equipped as in the previous preparation, place 200 ml. of absolute ethyl alcohol, 63 g. (64 -5 ml.) of pure anhydrous pyridine and 98 - 5 g. (84 5 ml.) of ethyl chloroacetate. Heat the mixture under reflux for 2-3 hours until the formation of the quaternary salt is complete acidify a small test-portion with dilute sulphuric acid it should dissolve completely and no odour of ethyl chloroacetate should be apparent. Cool the mixture in ice and salt. Replace the thermometer by a dropping funnel, and add a solution of 40 g. of 100 per cent, hydrazine hydrate in 60 ml. of absolute ethanol all at once. A vigorous exothermic reaction soon develops and is accompanied by vigorous effervescence. The pro duct separates almost immediately. When cold, filter with suction, wash... 

Phenol condenses with phthahc anhydride in the presence of concentrated sulphuric acid or anhydrous zinc chloride to yield the colourless phenolphthalein as the main product. When dilute caustic alkah is added to an alcoholic solution of phenolphthalein, an intense red colouration is produced. The alkali opens the lactone ring in phenolphthalein and forms a salt at one phenolic group. The reaction may be represented in steps, with the formation of a h3q)othetical unstable Intermediate that changes to a coloured ion. The colour is probably due to resonance which places the negative charge on either of the two equivalent oxygen atoms. With excess of concentrated caustic alkali, the first red colour disappears this is due to the production of the carbinol and attendant salt formation, rendering resonance impossible. The various reactions may be represented as follows ... 

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