Acetic acid temperature

Solvent, acetic acid temperature, 25°C. (Data from Mar and Winnik, 1981)... 

FIGURE 1.5 pH -effect on retention factors k and separation factors a. CSP 0-9- tert-butylcarbamoyl)quinine bonded to sihca column dimension, 150 x 4 mm ID eluent, methanol-ammonium acetate buffer (80 20, v/v) (adjusted with acetic acid) temperature, 25°C 1 mL min sample, N-benzoyl-leucine (Bz-Leu). (Reproduced from M. Lammerhofer et al., American Laboratory, 30 71 (1998). With permission.)... 

Solvent Acetic Acid, Temperature normal reflux... 

With glacial acetic acid, temperatures up to its boiling point, 118°C, may be used. This higher washing temperature—without pressure— removes impurities in less time than methanol, and at temperatures between 105° and 110°C, the raw sugar is refined in 45-90 min. 

Distillate flow rate Acetic acid Temperature Pressure Density... 

AcOMe = Methyl acetate MeOH = Methanol MA = Methyl acrylate AcOH = Acetic acid Temperature = 370 °C SV = 243-289 h". ... 

Optimum conditions for best product quality were found to be 200 °C and 1.5 MPa. The lower tanperatme also provides a stable operation with heat of the reaction being dissipated rapidly through evaporation of acetic acid. Temperature overshoot is undesirable because of possibility of rapid combustion of the solvent and titanium. 

Fig. 34.3 Total ion chromatogram (a) and extracted ion chromatogram (b) of a standard mixture solution, and extracted ion chromatogram (c) of Catharanthus roseus extract by CE-MS. CE conditions capillary, 65 cm length and 50 pm i.d, buffer 20 mM s ammonium acetate aqueous with 1.5 % acetic acid, temperature room temperature, sample, 50 mbar for 5 s injection MS-conditions ESI positive, sheath gas 4 psi dry gas 6 L/min dry temperature 130 °C capillary voltage 3.5 kV sheath liquid methanol/water = 1/1, with 0.1 % acetic acid flow rate of sheath liquid 4 pL/min. Peak identification 1 vinblastine 2 catharanthine 3 vindoline (From Ref. 8)... 

The azeotropic temperature determines the temperature difference between the top and the bottom of the column. A large delta T of the azeotropic temperature to the pure acetic acid temperature implies easy separability. Fewer column stages will be needed for specific product purity specifications. In this regard, ethyl acetate is the best entrainer. This interpretation is confirmed by Table 9.13 because the ethyl acetate system requires the least total number of stages for the same separation. 

Applications. Alloy B-2 has superior resistance to hydrochloric acid, aluminum chloride catalysts, and other strongly reducing chemicals and has excellent high-temperature strength in inert and vacuum atmospheres. Applications in the chemical process industry involve sulfuric, phosphoric, hydrochloric, and acetic acid. Temperature uses vary from ambient temperature to 820°C depending on the environments. 

Calcium complex soap greases, obtained by the reaction of lime and a mixture of fatty acids and acetic acid. These greases offer good high temperature and anti-wear/extreme pressure properties related to the presence, in the soap, of calcium acetate that acts as solid lubricant they have good mechanical stability. 

Dissolve I g. of finely powdered acetanilide in 5 ml. of cold glacial acetic acid contained in a 25 ml. conical flask. Then in another small flask prepare a solution of 0 42 ml. (1 34 g.) of bromine (care ) in 6 ml. of glacial acetic acid, and add this solution slowly to the acetanilide solution, shaking the latter throughout the addition to ensure thorough mixing. Allow the final mixture to stand at room temperature for 15 minutes. Then... 

Mix 6 2 ml. (6 4 g.) of pure ethyl acetoacetate and 5 ml. of pure phenylhydrazine in an evaporating-basin of about 75 ml. capacity, add 0 5 ml. of acetic acid and then heat the mixture on a briskly boiling water-bath (preferably in a fume-cupboard) for I hour, occasionally stirring the mixture with a short glass rod. Then allow the heavy yellow syrup to cool somewhat, add 30-40 ml. of ether, and stir the mixture vigorously the syrup may now dissolve and the solution shortly afterwards deposit the crystalline pyrazolone, or at lower temperatures the syrup may solidify directly. Note. If the laboratory has been inoculated by previous preparations, the syrup may solidify whilst still on the water-bath in this case the solid product when cold must be chipped out of the basin, and ground in a mortar with the ether.) Now filter the product at the pump, and wash the solid material thoroughly with ether. Recrystallise the product from a small quantity of a mixture of equal volumes of water and ethanol. The methyl-phenyl-pyrazolone is obtained... 

Fit a three necked 250 ml. flask with a central rubber-sleeved or mercury-sealed stirrer, c/. Fig. 23(c), p. 45, where only two necks are shown, and with a thermometer the bulb of which reaches as near the bottom of the flask as the stirrer allows the third neck will carry at first a dropping-funnel and later a reflux condenser. Place 20 g. (19-5 ml.) of ethyl acetoacetate and 45 ml. of glacial acetic acid in the flask and by ice-water cooling adjust the temperature of the stirred mixture to 5 -7° maintain this temperature whilst adding a solution of 5 4 g. of sodium nitrite in 8 ml. of water slowly from the dropping-funnel during 15 minutes. Continue the stirring for 20-30 minutes, and then... 

It is a well-known fact that substances like water and acetic acid can be cooled below the freezing point in this condition they are said to be supercooled (compare supersaturated solution). Such supercooled substances have vapour pressures which change in a normal manner with temperature the vapour pressure curve is represented by the dotted line ML —a continuation of ML. The curve ML lies above the vapour pressure curve of the solid and it is apparent that the vapour pressure of the supersaturated liquid is greater than that of the solid. The supercooled liquid is in a condition of metastabUity. As soon as crystallisation sets in, the temperature rises to the true freezing or melting point. It will be observed that no dotted continuation of the vapour pressure curve of the solid is shown this would mean a suspended transformation in the change from the solid to the liquid state. Such a change has not been observed nor is it theoretically possible. 

If the substance is found to be far too soluble in one solvent and much too insoluble in another solvent to allow of satisfactory recrystallisation, mixed solvents or solvent pairs may frequently be used with excellent results. The two solvents must, of course, be completely miscible. Recrystallisation from mixed solvents is carried out near the boiling point of the solvent. The compound is dissolved in the solvent in which it is very soluble, and the hot solvent, in which the substance is only sparingly soluble, is added cautiously until a slight turbidity is produced. The turbidity is then just cleared by the addition of a small quantity of the first solvent and the mixture is allowed to cool to room temperature crystals will separate. Pairs of liquids which may be used include alcohol and water alcohol and benzene benzene and petroleum ether acetone and petroleum ether glacial acetic acid and water. 

Transfer the reaction product to a 500 ml. Claisen flask and distil over a wire gauze or from an air bath. Some acetyl chloride and acetic acid passes over first, the temperature then rises, and the fraction, b.p. 150-200°, is collected separately run out the water from the condenser when the temperature reaches 150°. The fraction, b.p. 150-200°, solidifies on cooling. Drain off any hquid from the crystals as rapidly as possible, and redistil the solid using an air condenser. CoUect the fraction b.p. 182-192° this sets to a sohd mass on cooling and melts at 63°. The yield of monochloroacetic acid is 150-175 g. 

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. 

Add 25 g. of finely-powdered, dry acetanilide to 25 ml. of glacial acetic acid contained in a 500 ml. beaker introduce into the well-stirred mixture 92 g. (50 ml.) of concentrated sulphuric acid. The mixture becomes warm and a clear solution results. Surround the beaker with a freezing mixture of ice and salt, and stir the solution mechanically. Support a separatory funnel, containing a cold mixture of 15 -5 g. (11 ml.) of concentrated nitric acid and 12 -5 g. (7 ml.) of concentrated sulphuric acid, over the beaker. When the temperature of the solution falls to 0-2°, run in the acid mixture gradually while the temperature is maintained below 10°. After all the mixed acid has been added, remove the beaker from the freezing mixture, and allow it to stand at room temperature for 1 hour. Pour the reaction mixture on to 250 g. of crushed ice (or into 500 ml. of cold water), whereby the crude nitroacetanilide is at once precipitated. Allow to stand for 15 minutes, filter with suction on a Buchner funnel, wash it thoroughly with cold water until free from acids (test the wash water), and drain well. Recrystallise the pale yellow product from alcohol or methylated spirit (see Section IV,12 for experimental details), filter at the pump, wash with a httle cold alcohol, and dry in the air upon filter paper. [The yellow o-nitroacetanihde remains in the filtrate.] The yield of p-nitroacetanihde, a colourless crystalline sohd of m.p. 214°, is 20 g. 

Equip a I litre three-necked flask with a mechanical stirrer and a thermometer, and immerse the flask in a bath of ice and salt. Place 306 g. (283 ml.) of acetic anhydride, 300 g. (285 ml.) of glacial acetic acid and 25 g. of p-nitrotoluene in the flask, and add slowly, with stirring, 42 5 ml. of concentrated sulphuric acid. When the temperature has fallen to 5°, introduce 50 g. of A.R. chromic anhydride in small portions at such a rate that the temperature does not rise above 10° continue the stirring for 10 minutes after all the chromium trioxide has been added. Pour the contents of the flask into a 3 litre beaker two-thirds filled with crushed ice and almost fill the beaker with cold water. Filter the solid at the pump and wash it with cold water until the washings are colourless. Suspend the product in 250 ml. of cold 2 per cent, sodium carbonate solution and stir mechanically for 10-15 minutes filter (1), wash with cold water, and finally with 10 ml. of alcohol. Dry in a vacuum desiccator the yield of crude p-nitrobenzal diacetate is 26 g. (2),... 

To the clear solution obtained by warming 0-5 g. of 2 4-dinitro-phenylhydrazine, 1 ml. of concentrated hydrochloric acid and 8- 10 ml. of ethanol, add 0-25 g. of the aldehyde and heat just to boiling. Allow to cool to room temperature, filter off the 2 4-dinitrophenylhydiuzone and recrystallise it from ethanol or glacial acetic acid. 

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