Ethanol solution preparation

The new system was applied for standard ethanol solutions prepared in phosphate buffer solutions (pH 7.0). Extracted ethanol solutions were also used with 10% (w/v) NaCl by NBR 13992 1997 from gasohol blends (12) (Brazilian Association Technical Standard). Table 3 shows the concentrations of the extracted ethanol solutions measured by HPLC and respective gasoholblends. This new integrated system biosensor-FIA was used for the range of 0.05-1.5 g of ethanol/L, and good results were obtained compared with the ethanol content measured by the HPLC standard method. 

Construct a calibration cnrve for Santonox R in 50% w v ethanol in the concentration range 2 to 20 ppm. Snitable standard solutions may be prepared by quantitative dilntion of a 100 ppm solntion of Santonox R in neat ethanol adjusting the ethanol content of the standard solntions to 50% wIv. Note that the concentration of Santonox R in the test extractant is 2.27 times the concentration of Santonox R in the ethanolic solution prepared previously. 

Mono and Di-iubstitution Derivatives. The enolic sodium derivative of ethyl acetoacetate (E) is prepared by mixing ethanolic solutions of the ester and of sodium ethoxide. It should not be prepared by the direct action of metallic sodium on the ester, as the reaction is slow and the nascent hydrogen evolved reduces some of the ester to ethyl p4iydroxy- butyrate, CH3CH(OH)CHjCOOEt. 

Thiourea. Boil in ethanolic solution with benzyl chloride to prepare the crystalline benzylthiouronium chloride, m.p. lyo i 74" (P- 126). 

A solution of potassium ethoxide in ethanol was prepared by adding 4.0 g of... 

Poly(acrylic acid) and Poly(methacrylic acid). Poly(acryHc acid) (8) (PAA) may be prepared by polymerization of the monomer with conventional free-radical initiators using the monomer either undiluted (36) (with cross-linker for superadsorber appHcations) or in aqueous solution. Photochemical polymerization (sensitized by benzoin) of methyl acrylate in ethanol solution at —78° C provides a syndiotactic form (37) that can be hydrolyzed to syndiotactic PAA. From academic studies, alkaline hydrolysis of the methyl ester requires a lower time than acid hydrolysis of the polymeric ester, and can lead to oxidative degradation of the polymer (38). Po1y(meth acrylic acid) (PMAA) (9) is prepared only by the direct polymerization of the acid monomer it is not readily obtained by the hydrolysis of methyl methacrylate. 

The indicator was prepared by the method of Oiehl and Einhorn. A solution of 5 g of sodium hydroxide in 50 mL of water and 40 ml of ethanol is prepared in a 250-mL Erlenmeyer flask. To this is added a solution of 1.64 ml (0.025 mol, 1.45 g) of acetone in 6.3 mL (0.050 mol, 5.6 g) of freshly distilled cinnamaldehyde (Note 1). This mixture is stirred thoroughly at room temperature for 30 min. The resulting voluminous yellow precipitate is filtered with suction, washed with 100 mL of water, and dried, affording 6.5 g of l,9-diphenylnona-l,3,6,8-tetraen-5-one. Recrystallization from 200 mL of hot 9511 ethanol gives 3.5 g of yellow crystals, mp 142-143 C (lit mp 142°C). This indicator is also available from Aldrich Chemical Co. 

Hydrolysis of the ester is achieved by refluxing in aqueous N or 2N NaOH solution until the insoluble ester dissolves. The solution is then cooled, and the alcohol is extracted into a suitable solvent, e.g. ether, toluene or alcohol-free chloroform. The extract is dried (CaS04, MgS04) and distilled, then fractionally distilled if liquid or recrystallised if solid. (The p-nitrobenzoic acid can be recovered by acidification of the aqueous layer.) In most cases where the alcohol to be purified can be readily extracted fi-om ethanol, the hydrolysis of the ester is best achieved with N or 2N ethanolic NaOH or 85% aqueous ethanolic N NaOH. The former is prepared by dissolving the necessary alkali in a minimum volume of water and diluting with absolute alcohol. The ethanolic solution is refluxed for one to two hours and hydrolysis is complete when an aliquot gives a clear solution on dilution with four or five times its volume of water. The bulk of the ethanol is distilled off and the residue is... 

The purity of the 2-cyclohexenone may be assayed by gas chromatography on an 8 mm. x 215 cm. column heated to 125° and packed with di-(2-ethylhexyl) sebacate suspended on ground firebrick. This method of analysis indicates that the 3-cyclo-hexenone in the product amounts to no more than 3%. The fore-run from this fractional distillation contains substantial amounts of 2-cyclohexenone accompanied by ether, ethanol, and minor amounts of other lower-boiling impurities. Additional quantities of pure 2-cyclohexenone can be recovered by redistillation of this fore-run. The preparation of 2-cyclohexenone has been run on twice the scale described with no loss in yield. The ultraviolet spectrum of an ethanol solution of the 2-cyclohexenone obtained has a maximum at 226 m/i (s = 10,400). 

A number of bridged crown ethers have been prepared. Although the Simmons-Park in-out bicyclic amines (see Sect. 1.3.3) are the prototype, Lehn s cryptands (see Chap. 8) are probably better known. Intermediates between the cryptands (which Pedersen referred to as lanterns ) and the simple monoazacrowns are monoazacrowns bridged by a single hydrocarbon strand. Pedersen reports the synthesis of such a structure (see 7, below) which he referred to as a clam compound for the obvious reason . Although Pedersen appears not to have explored the binding properties of his clam in any detail, he did attempt to complex Na and Cs ions. A 0.0001 molar solution of the clam compound is prepared in ethanol. The metal ions Na and Cs are added to the clam-ethanol solutions as salts. Ultraviolet spectra of these solutions indicate that a small amount of the Na is complexed by the clam compound but none of the Cs . 

Androst-4-ene-3,17-dione. Testosterone (0.58 g, 2 mmoles) is dissolved in a solution prepared from 3 ml of benzene, 3 ml of dimethyl sulfoxide, 0.16 ml (2 mmoles) of pyridine and 0.08 ml (1 mmole) of trifluoroacetic acid. After addition of 1.24 g (6 mmoles) of dicyclohexylcarbodiimide, the sealed reaction flask is kept overnight at room temperature. Ether (50 ml) is added followed by a solution of 0.54 g (6 mmoles) of oxalic acid in 5 ml of methanol. After gas evolution has ceased ( 30 min) 50 ml of water is added and the insoluble dicyclohexylurea is removed by filtration. The organic phase is then extracted twice with 5 % sodium bicarbonate and once with water, dried over sodium sulfate and evaporated to a crystalline residue (0.80 g) which still contains a little dicyclohexylurea. Direct crystallization from 5 ml of ethanol gives androst-4-ene-3,17-dione (0.53 g, 92%) in two crops, mp 169-170°. 

To an ethanolic solution of sodium ethoxide prepared by addition of 0.46 g (0.02 mole) of freshly cut sodium metal in 100 mL of absolute ethanol was slowly added 5.10 g (0.02 mole) of ethyl 4-nitrobenzylthioacetate 28 with stirring at 5°C. The mixture was refluxed for about 4 to 6 hours until the reaction was complete (monitored by tic). The resultant mixture was allowed to cool to room temperature and then added into an ice-water mixture. The solution was neutralized with slow addition of dilute aqueous hydrochloric acid (10%). The precipitated solid was removed by filtration, washed with water, and recrystallized from a dimethylformamide-ethanol (T.l) mixture yielding 2.10 g (76 %) of 29 as a light brown crystalline solid, mp 227°C ir (nujol) (neat (1710 cm ms m/z Til (NT). Anal. Calcd. For C13H11NO4S C, 56.31 H, 3.97 N, 5.05 S, 11.55. Found C, 56.36 H, 3.95 N, 5.01 S, 11.49. 

The structure of this compound is confirmed by the preparation of the 1-acetyl derivative, acid degradation to 4-methylquinoxalin-3-one-2-carboxylic acid (12), and alternative synthesis from the acid chloride of (12) and AW -dimethyluread A most unusual cyclization occurs when AW-dimethyl-o-phenylenediamine (15) is treated with alloxan in ethanolic solution this apparently involves an A-methyl group and leads to the formation of the spirobarbituric acid (16). The struc-... 

In an initial step, the sodium derivative of ethyl (3-benzoylphenyl)cyanoecetate is prepared as follows (3-benzoylphenyl)acetonitrile (170 g) is dissolved in ethyl carbonate (900 g). There is added, over a period of 2 hours, a sodium ethoxide solution [prepared from sodium (17.7 g) and anhydrous ethanol (400 cc)], the reaction mixture being heated at... 

The methionine nitrile (20 g) is dissolved in a solution prepared from 50 ml of aqueous 5N sodium hydroxide solution and 65 ml of ethanol. The solution is then refluxed for 24 hours ammonia is evolved. The solution is treated with activated carbon, filtered, acidified with glacial acetic acid (17 ml), chilled to -10°C and filtered to give crude product. This crude product is then slurried with a solution made up of 20 ml of water and 20 ml of methanol, filtered at -5° to -H0°C and dried to give dl-methionine as white platelets. 

Preparation of Diethyl Allyl (1-Methyl-2-Pentynyl) Malonate A solution of 12.1 g of sodium in 182 ml of absolute ethanol was prepared, and thereto were added 126.6 g of diethyl (1-methyl-2-pentynyl) malonate. Most of the ethanol was then distilled off under reduced pressure, and the residue was cooled and 63.5 g of allyl bromide were slowly added thereto. After completion of the addition, the mixture was refluxed for about 1 hour. 

B. 2-Bromoallylatnine. Crude 2-bromoallylhexaminium bromide (204 g., 0.60 mole) is dissolved in a warm solution prepared from 400 ml. of water, 2 1. of ethanol, and 480 ml. (S.8 moles) of 121V hydrochloric acid. A white precipitate of ammonium chloride forms within an hour. The reaction mixture is allowed to stand for 24 hours, and the precipitate is removed by suction filtration. The mother liquor is concentrated to a volume of 600 ml. (Note 3), and the precipitate (Note 4) is removed by suction filtration. The mother liquor is evaporated to dryness (Note 5), and the residue is dissolved in 300 ml. of water. The solution is cooled in an ice bath and made strongly alkaline (pH 13) with 6N sodium hydroxide solution. 

Sfi.f-Test 8.1 IB Calculate the vapor pressure of ethanol in kilopascals (kPa) at 19°C for a solution prepared by dissolving 2.00 g of cinnamaldehyde, C9HkO, in 50.0 g of ethanol, C2F-I5OH. The vapor pressure of pure ethanol at that temperature is 5.3 kPa. 

Dimethyl-6-methylamino-5-quinoxalinamine (175) (prepared freshly as an ethanolic solution by catalytic hydrogenation of the corresponding nitro compound) and cyanogen bromide gave 3,4,8-trimethyl-3//-imidazo-[4,5-/]quinoxalin-2-amine (176) (20°C, 3.5 h 75%) the analogous... 

This procedure results in higher yields (60-80%) than achieved with the sodium borohydride method (10-60%). Apart from the preparation route described above, [Au, (PPh3)7][SCN]3 may be prepared through evaporation of Au onto an ethanolic solution of KSCN and PPh3. 

As discussed earlier by Senthilnathan and Hurtubise (4), before a saturated ethanol solution of sodium acetate is formed, the solid-surface RTF is less than the RTF from samples prepared with solutions that are saturated with sodium acetate. It was shown by Ramasamy and Hurtubise (12) that both the RTF and RTF quantum yields of the p-aminobenzoic acid anion increased as the amount of sodium acetate increased in the solid mixtures. Figure 4 shows the quantum yield of fluorescence and the quantum yield of phosphorescence )... 

Ethanol formulations of salicylic acid (20 and 30%) are used for combination peeling (see salicylic acid section). Trichloroacetic acid is prepared as an aqueous solution, since ethanol solutions do not penetrate the skin. It is prepared by mixing the appropriate concentration of crystals with up to 100 cc of distilled water. Ten and fifteen percent TCA is prepared by mixing 10 or 15 g of crystals in up to 100 cc of total volume, respectively. Aqueous solutions of TCA remain stable for up to 6 months unless contaminated. Other methods have been used to formulate TCA peeling solutions however, the weight/volume methods appear to be the most reliable formulation [5]. Premixed TCA solutions are available from a variety of medical... 

---