Drying reduction

The third strategy for minimizing NOx, known as posttreatment, involves removing NOx from the exhaust gases after the NOx has already been formed in the combustion chamber. Two of the most common methods of posttreatment are selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR).7 Wet techniques for posttreatment include oxidation/absorption, oxidation/absorption/reduc-tion, absorption/oxidation, and absorption/reduction. Dry techniques for posttreatment, besides SCR and SNCR, include activated carbon beds, electron beam radiation, and reaction with hydrocarbons. 

Pseudokirchneriella subcapitata (formerly Selenastrum capricomutum) [32,68,72,74-76,78] FW Population growth Chlorophyll a reduction Dry weight reduction 96-h EC50 96-h IC50 120-h LOEC 120-h EC30 96-h EC30 >144.1 >165.2 >181.0... 

Growth reduction (dry weight tubercle bacilli 5 mg) by a given concentration in pg/mL determined in glycerin-bouillon after 3 weeks incubation at 37°C. 

CsHsO. Colourless, crystalline solid m.p. 115 C. Prepared by the dry distillation of tartaric acid or by reduction of itaconic or cilra-conic acids. Forms an anhydride when heated to 200"C. 

After oxygen, silicon is the most abundant element in the earth s crust, It occurs extensively as the oxide, silica, in various forms, for example, flint, quartz, sand, and as silicates in rocks and clays, but not as the free element, silicon. Silicon is prepared by reduction of silica, Si02- Powdered amorphous silicon can be obtained by heating dry powdered silica with either powdered magnesium or a... 

Pure phosphine can be prepared by the reduction of a solution of phosphorus trichloride in dry ether with lithium aluminium hydride ... 

Now cool the mixture thoroughly in ice-water, and run in over a period of 45 minutes a solution of 6 o g. of dry salicylic acid in 75 ml. of dry ether. When the addition of the acid to the stirred solution is complete, heat the mixture under reflux on the water-bath for 15 minutes to ensure completion of the reduction. Then thoroughly chill the mixture in ice-water, and hydrolyse any unused hydride by the slow addition of 50 ml. of ordinary undried ether, followed similarly by 75 ml. of dilute sulphuric acid. 

Reduction. Mix together intimately in a dry hard-glass test-tube o-i g. of... 

Metallic sodium. This metal is employed for the drying of ethers and of saturated and aromatic hydrocarbons. The bulk of the water should first be removed from the liquid or solution by a preliminary drying with anhydrous calcium chloride or magnesium sulphate. Sodium is most effective in the form of fine wire, which is forced directly into the liquid by means of a sodium press (see under Ether, Section II,47,i) a large surface is thus presented to the liquid. It cannot be used for any compound with which it reacts or which is affected by alkalis or is easily subject to reduction (due to the hydrogen evolved during the dehydration), viz., alcohols, acids, esters, organic halides, ketones, aldehydes, and some amines. 

Extremely dry (or super-dry ) ethyl alcohol. The yields in several organic preparations e.g., malonic ester syntheses, reduction with sodium and ethyl alcohol, veronal synthesis) are considerably improved by the use of alcohol of 99-8 per cent, purity or higher. This very high grade ethyl alcohol may be prepared in several ways from commercial absolute alcohol or from the product of dehydration of rectified spirit with quicklime (see under 4). 

All the products of Clemmensen reductions contain small amounts of un-saturated hydrocarbons. These can be removed by repeated shaking with 10 per cent, of the volume of concentrated sulphuric acid until the acid is colourless or nearly so each shaking should be of about 5 minutes duration. The hydrocarbon is washed with water, 10 per cent, sodium carbonate solution, water (twice), dried with anhydreus magnesium or calcium sulphate, and finally distilled twice from a Claisen flask with fractionating side arm (or a Widmer flask) over sodium. 

The best results are obtained with freshly prepared xanthhydrol (reduction of xanthone with sodium amalgam. Section VII,16). Dissolve 0 -25 g. of xanthhydrol and 0 -25g. of the primary sulphonamide in 10 ml. of glacial acetic acid. Shake for 2-3 minutes at the laboratory temperature and allow to stand for 60-90 minutes. Filter oflf the derivative, recrystallise it from dioxan-water (3 1), and dry at room temperature under water pump suction for 30 minutes. 

Reduction of A-nitrosomethylaniline. Into a 1 litre round-bottomed flask, fitted with a reflux condenser, place 39 g. of A-nitroso-methylaniline and 75 g. of granulated tin. Add 150 ml. of concentrated hydrochloric acid in portions of 25 ml. (compare Section IV.34) do not add the second portion until the vigorous action produced by the previous portion has subsided, etc. Heat the reaction mixture on a water bath for 45 minutes, and allow to cool. Add cautiously a solution of 135 g. of sodium hydroxide in 175 ml. of water, and steam distil (see Fig. II, 40, 1) collect about 500 ml. of distillate. Saturate the solution with salt, separate the organic layer, extract the aqueous layer with 50 ml. of ether and combine the extract with the organic layer. Dry with anhydrous potassium carbonate, remove the ether on a water bath (compare Fig. II, 13, 4), and distil the residual liquid using an air bath (Fig. II, 5, 3). Collect the pure methylaniline at 193-194° as a colourless liquid. The yield is 23 g. 

In a 500 ml. bolt-head flask, provided with a mechanical stirrer, place 70 ml. of oleum (20 per cent. SO3) and heat it in an oil bath to 70°. By means of a separatory funnel, supported so that the stem is just above the surface of the acid, introduce 41 g. (34 ml.) of nitrobenzene slowly and at such a rate that the temperature of the well-stirred mixture does not rise above 100-105°. When all the nitrobenzene has been introduced, continue the heating at 110-115° for 30 minutes. Remove a test portion and add it to the excess of water. If the odour of nitrobenzene is still apparent, add a further 10 ml. of fuming sulphuric acid, and heat at 110-115° for 15 minutes the reaction mixture should then be free from nitrobenzene. Allow the mixture to cool and pour it with good mechanical stirring on to 200 g. of finely-crushed ice contained in a beaker. AU the nitrobenzenesulphonic acid passes into solution if a little sulphone is present, remove this by filtration. Stir the solution mechanically and add 70 g. of sodium chloride in small portions the sodium salt of m-nitro-benzenesulphonic acid separates as a pasty mass. Continue the stirring for about 30 minutes, allow to stand overnight, filter and press the cake well. The latter will retain sufficient acid to render unnecessary the addition of acid in the subsequent reduction with iron. Spread upon filter paper to dry partially. 

Reduction of methyl orange to />-aminodimethylaniline. Method 1. Dissolve 2 0 g. of methyl orange in the minimum volume of hot water and to the hot solution add a solution of 8 g. of stannous chloride in 20 ml. of concentrated hydrochloric acid until decolourisation takes place gentle boiling may be necessary. Cool the resulting solution in ice a crystalline precipitate consisting of sulphanilic acid and some p-aminodimethylaniline hydrochloride separates out. In order to separate the free base, add 10 per cent, sodium hydroxide solution until the precipitate of tin hydroxide redisaolves. Extract the cold solution with three or four 20 ml. portions of ether, dry the extract... 

The compound is generally employed in solution in dry ether this solution is conducting and the reduction may be due to the transfer of a hydride ion ... 

For many reductions it is not necessary to distil the reagent. Dilute the dark solution, prepared as above to the point marked with an asterisk, to 1 htre with dry isopropyl alcohol this gives an approximately one molar solution. Alternatively, prepare the quantity necessary for the reduction, using the appropriate proportions of the reagents. 

Place 35 ml. of a M solution of aluminium tsopropoxide or 7 g. of solid aluminium tsopropoxide, 450 ml. of dry isopropyl alcohol and 21 g. of purified benzaldehyde (Section IV,115) in a 1 litre round-bottomed flask. Fit a short reflux condenser (no water in the cooling jacket) or better a Hahn condenser (2) (containing a 1 cm. layer of ethyl alcohol in the iimer tube) to the flask and arrange for slow distillation from a water bath at the rate of 3-6 drops per minute. Continue the heating until a negative test for acetone is obtained after 5 minutes of total reflux (6-9 hours) if the volume of the mixture falls below 200 ml. during the reduction, add more isopropyl alcohol. Remove the reflux or Hahn condenser and distil off (Fig. II, 13, 3) most of the isopropyl alcohol under atmospheric pressure from a suitable oil bath. Hydrolyse the... 

The addition of N-bromosuccinimide (1.1equiv) to a dichlo-romethane solution containing the alkene (1 equiv) and cyana-mide (4 equiv). The solution was maintained at room temperature (3 days) and then washed with water, dried, and concentrated in vacuo. Treatment of the bromocyanamide [intermediate] with 1% palladium on charcoal in methanol (1h) led to reduction of the for-madine. Addition of base to the reaction mixture (50% aqueous KOH, reflux 6h) followed by extraction with ether gave monoamine. (Yield is 48-64% final amine from alkenes analogous to safrole)... 

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