Heating/cooling methods steam baths

Indane-1 3-dione (1 3-diketohydrindene). Method A. To a solution of sodium methoxide, prepared from 6 1 g. of sodium and 200 ml. of anhydrous methanol, add 15 g. of phthalylacetic acid and allow to stand for 1 hour at room temperature collect the yellow precipitate by suction filtration. Mix the yellow solid with 150 ml. of 10 per cent, sulphuric acid, heat on a steam bath until no more carbon dioxide is evolved (15-20 minutes), filter the hot solution and allow to cool. Collect the yellow crystals by filtration at the pump, wash with a httle water and dry at 100°. The yield of crude 1 3-indanedione, m.p. 125-126°, is 7 g. RecrystaUise from hght petroleum, b.p. 80-100°, and thus obtain the pure product, m.p. 129-130°. 

Method B (one-pot procedure)-. 5 g (33 mmol) of L-arabinose. 12 mL of ethanol and 4mL (36.7 mmol) of bcnzylaminc arc heated on a steam bath for 5 to 10 min to give a clear solution. After cooling, 2.5 mL of anliyd hydrogen cyanide are added. Spontaneous crystallization of the product begins within a few minutes. After cooling for 2 h with an ice-bath, the product is isolated by filtration and washed with ethanol yield 7.0-7.5g (79-85%) nip 129-131 C after recrystallization from ethanol mp 130-132 C. 

Schnepfe [83] has described yet another procedure for the determination of iodate and total iodine in seawater. To determine total iodine 1 ml of 1% aqueous sulfamic acid is added to 10 ml seawater which, if necessary, is filtered and then adjusted to a pH of less than 2.0. After 15 min, 1 ml sodium hydroxide (0.1 M) and 0.5 ml potassium permanganate (0.1M) are added and the mixture heated on a steam bath for one hour. The cooled solution is filtered and the residue washed. The filtrate and washings are diluted to 16 ml and 1ml of a phosphate solution (0.25 M) added (containing 0.3 xg iodine as iodate per ml) at 0 °C. Then 0.7 ml ferrous chloride (0.1 M) in 0.2% v/v sulfuric acid, 5 ml aqueous sulfuric acid (10%) - phosphoric acid (1 1) are added at 0 °C followed by 2 ml starch-cadmium iodide reagent. The solution is diluted to 25 ml and after 10-15 min the extinction of the starch-iodine complex is measured in a -5 cm cell. To determine iodate the same procedure is followed as is described previously except that the oxidation stage with sodium hydroxide - potassium permanganate is omitted and only 0.2 ml ferrous chloride solution is added. A potassium iodate standard was used in both methods. 

Assay Dissolve about 1 g of sample, accurately weighed, in 50 mL of water, add 50.0 mL of 0.05 M disodium EDTA and 20 mL of pH 4.5 buffer solution (77.1 g of ammonium acetate and 57 mL of glacial acetic acid in 1000 mL of aqueous solution), and boil gently for 5 min. Cool, and add 50 mL of alcohol and 2 mL of dithizone TS. Back titrate with 0.05 M zinc sulfate to a bright rose-pink color. Perform a blank determination (see General Provisions), and make any necessary correction. The milliliters of 0.05 M disodium EDTA consumed is equivalent to 50 minus the milliliters of 0.05 M zinc sulfate used. Each milliliter of 0.05 M disodium EDTA is equivalent to 23.72 mg of A1K(S04)2T2H20. Ammonium Salts Add 1 g of sample to 10 mL of 1 N sodium hydroxide in a small beaker, and heat on a steam bath for 1 min. The odor of ammonia is not perceptible. Fluoride Determine as directed in Method V under Fluoride Limit Test, Appendix IIIB. 

In the Power-Chesnut method, lOg of coffee sample is transferred into a Soxhlet extractor with ethanol, and extracted with ethanol for up to 8h. The ethanolic extract is transferred into a porcelain dish containing lOg of high-density MgO and 100 ml of water. Ethanol in the mixture is evaporated by slow heating on a steam bath. The residue is moistened with hot water and filtered into a 11 flask. The filtrate is acidified with 20 ml of sulfuric acid and brought to boiled for 30 min. After cooling, the acid extract is filtered into a separator. The filtrate is extracted with chloroform (six 25 ml portions). The combined chloroform extract is washed with 5 ml of 1 % KOH solution. The chloroform phase is drained into an Erlenmeyer flask and the KOH portion is washed with two portions of chloroform (10 ml each). All chloroform extracts are pooled, and the volume of extract is reduced to 10 or 15 ml by distillation. The remaining chloroform extract is transferred to a weighing beaker, and the residual solvent is... 

Nitrosomethylurea. Acetamide method. To a solution of 59 g. of acetamide in 88 g. (28 ml.) of bromine (1) in a 4-litre beaker add dropwise, with hand stining, a solution of 40 g. of sodium hydroxide in 160 ml. of water. Heat the resulting yellow reaction mixture on a steam bath until eflfervescence sets in (2), after which continue the heating for 2-3 minutes. CrystaUisation of the product from the yellow or red coloured solution usually commences immediately. Cool in an ice bath for 1-2 hours, collect the product by suction filtration, wash with a little ice-cold water, and dry in the air. The yield of colourless acetylmethylurea, m.p. 178-180°, is 50 g. 

Method B. Place 125 g. (106 -5 ml.) of diethyl phthalate and 25 g. of molecular sodium (sodium sand see Section 11,50,6) in a 500 ml. round-bottomed flask fitted with a reflux condenser and dropping funnel. Heat the flask on a steam bath and add a mixture of 122 5 g. (136 ml.) of dry ethyl acetate and 2 5 ml. of absolute ethanol over a period of 90 minutes. Continue the heating for 6 hours, cool and add 50 ml. of ether. Filter the sodium salt (VI) on a sintered glass funnel and wash it with the minimum volume of ether. Dissolve the sodium salt (96 g.) in 1400 ml. of hot water in a 3-htre beaker, cool the solution to 70°, stir vigorously and add 100 ml. of sulphuric acid (3 parts of concentrated acid to 1 part of... 

The crude liquid acid (about 300 g.) is cooled with running water and 15 cc. of concentrated sulfuric acid is added the clear yellow oil becomes cloudy. The acid is esterified by the method described in Org. Syn. 3, 54, with the following changes all three flasks, the alcohol flask, the trap, and the esterification flask are i-l. round-bottom wide-neck flasks. The alcohol flask and the trap are set on adjacent steam baths. The esterification flask is placed in an oil bath which is heated by a free flame. A safety tube leads from the alcohol flask and dips under 7.5 cm. of mercury contained in a side-arm tube. 

Schnepfe [4] has described a method for the determination of total iodine and iodate in seawater. One per cent aqueous sulfamic acid (1 ml) is added to seawater (10 ml), then it is filtered, if necessary, and the pH adjusted to 2. After 15 min, 1 ml 0.1 M sodium hydroxide and 0.5 ml 0.1 M potassium permanganate are added and the steam bath heated for 1 h. The cooled solution is filtered, the residue washed, the filtrate plus washings is diluted to 16 ml and 1 ml of a 0.25 M phosphate solution (containing 0.3 pg iodine as IOj per... 

Laboratory Preparation. Davis (Ref. 3, p 380) gives this method On a 160° oil bath heat a 1-liter flask contg an intimate mixt of 210g dicyandiamide and 44Qg AN. After 2 hrs, cool to RT. Then place on a steam bath and extract... 

Test 1. DPhA Nitration Method Cut a sample of proplnt into small pieces, as described in Vol 2 of Encycl, p C131-L, under "Preparation of Sample", and weigh ca 5g, within 0.2mg, in a tared 250ml lipped beaker. Add a mixture of 10ml glac AcOH and 20ml nitric acid of density 1.42 and heat the beaker on a steam bath at 95° for 1 lA hours Cool the beaker with contents but do not agitate. Pout... 

If the anhydrous (98-100%) ethylenediamine is not available, it may be prepared from the aqueous 70% product as follows One hundred grams of solid sodium hydroxide and 175ml of 70% ethylenediamine are heated in a flask with an air condenser on the steam bath overnight. (As the amine attacks corks and rubber stoppers readily, these should be covered with tin foil.) The two layers that form are separated after cooling and the upper one is heated again for several hours with 30g more of the solid alkali. When distilled, the yield of amine, boiling at 115-118°C, is almost quantitative. This method is also used to dehydrate propylenediamine b.p. 118-120° C. 

Method II.—50 gms. /5-naphthol and 200 gms. powdered zinc-ammonium chloride are mixed and heated on an oil bath in a vessel provided with a reflux condenser for 2 hours at 200°. The product, after cooling, is treated with 25% caustic soda solution until the zinc oxide redissolves, and the solution boiled for a few minutes. On cooling, -naphthylamine separates. It may be removed and purified, as described in Method I. It may also be separated by extraction with ether, or by distillation in a current of superheated steam. (B., 13, 1300.)... 

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