Sodium hydroxide solutions index

The distillate may contain volatile neutral compounds as well as volatile acids and phenols. Add a slight excess of 10-20 per cent sodium hydroxide solution to this distillate and distil until it is judged that all volatile organic compounds have passed over into the distillate. If necessary, the determination of the refractive index of the distillate or the application of specific chemical tests (e.g. for carbonyl compounds use the 2,4-dinitrophenylhydrazine reagent) should be used to confirm completion of distillation. Keep this distillate (S,) for Step 4. 

Preparation of 2-Allylphenol. The allyl ether is boiled in a flask under a reflux tube, the course of the rearrangement being conveniently followed by noting the refractive index at frequent intervals. When nu has risen to 1.55 (five to six hours) the rearrangement is substantially complete with the minimum formation of undesirable by-products. To separate a small amount of 2-methyldihydrobenzofuran, the product is dissolved in tivice its volume of 20% sodium hydroxide solution and extracted twice with petroleum ether (30-60°), from which the dihydro-benzofuran residue may be obtained by distillation. Ether should not be used for this extraction as it removes some of the phenol from the alkaline solution. The alkaline solution is acidified and the phenpl extracted with ether the extract is dried over calcium chloride and distilled under diminished pressure. A 73% yield of material boiling at 103-105.5°/19 mm., no 1.5445, is obtained. 2-Allylphenol is a colorless liquid, of guaiacol-like odor, with the following properties b.p. 220°/ 760 mm., 99°/12 mm., nf) 1.5453. ... 

At the end of the transformation, acetic anhydride in excess is hydrolyzed in acetic acid, which is directly titrated in the reaction medium with a sodium hydroxide solution in the presence of phenolphthalein. The same operations are realized with a blank in which there is no hydroxylated derivative, all the other experimental conditions being the same as in the assay. The difference between both volumes added gives the number of moles of acetic acid used for the esterification. The in pyridine acetylation index is of great interest in the analysis of essential vegetable oils, fats, and numerous pharmaceutical compounds, including, for instance, the determinations of cetylic and benzylic alcohols. The propionyl index is based on the same principle, but all of the operations are performed in a nonaqueous medium. 

The allyl phenyl ether is rearranged by boiling at 195°-200 C at atmospheric pressure under nitrogen until the refractive index of the liquid remains constant (5 to 6 hr to get nl 1.55). The crude material is dissolved in 20% sodium hydroxide solution and extracted twice with 30°-60°C petroleum ether. The alkaline solution is acidified, extracted with ether, dried, the solvent stripped off, and the remaining liquid distilled under reduced pressure to yield 73% of 2-allylphenol, bp 103°-105.5°C (19 mm), 1.5445. 

The range of hydrogen ion concentration between the dilute solutions of hydrochloric acid and sodium hydroxide encompasses a factor of 1 x 10 2. Because these concentrations cover such a vast range, even for dilute solutions, a scale has been devised to make the numbers more manageable. Notice that the index in the concentration terms changes from -1 for the dilute hydrochloric acid to -13 for the dilute sodium hydroxide solution. This is the basis of the scale, known as the pH scale, in which pH is defined as... 

Natural azurite is blue monoclinic crystal density 3.88 g/cm refractive index 1.730 decomposes at 220°C insoluble in cold water decomposes in hot water soluble in ammonium hydroxide and hot sodium bicarbonate solutions. 

Dissolve 2.5 g of sodium hydroxide in 250 ml of water in a 500-ml two-necked flask fitted with a reflux condenser and a dropping funnel. Bring the solution to the boil, add rapidly from the dropping funnel 28.5 g (0.25 mol) of hexane-2, 5-dione (Expt 5.104) and continue to boil steadily under reflux for exactly 15 minutes (1). Cool the resulting dark-brown solution rapidly in an ice-salt bath, saturate with sodium chloride and extract with one 100 ml and two 50 ml portions of ether. Wash the ether extract with three 5 ml portions of water, dry over anhydrous sodium sulphate and remove the ether on a rotary evaporator. Distil the residual dark oil under reduced pressure and collect the colourless 3-methylcyclopent-2-enone as a fraction of b.p. 74-76 °C/ 16mmHg, n 0 1.4818 yield 9.5 g (40%). The product thus obtained is pure enough for most purposes when perfectly pure the refractive index is 1.4893. The product may darken on storage. 

Methyl monochloride is synthesised at 0-5 °C. The temperature in the reactor is maintained by regulating the supply of salt solution into the coil and the jacket of the apparatus, as well as by regulating the speed at which sodium hydroxide enters the reactor. After the necessary amount of alkali solution has been supplied, the reactive mixture is agitated for 30 more minutes at 0 °C. The end of the reaction is determined by the refraction index of the product. For this purpose, an average sample is taken and flushed with water the organic layer is used to determine the refraction index, which should not exceed 1.4820 or fall below 1.4810. 

Eluent. A solution containing 1.175 g (0.01 M) of ammonium perchlorate in 1000ml of methanol adjust to pH 6.7 by the addition of 1 ml of 0.1 M sodium hydroxide in methanol. k Values. Values for drugs in this system will be found in drug monographs and in the indexes to Analytical Data in Part 3 they are also included in the systems for specific groups of drugs which follow. 

D) Reduction of Iodoform to Methylene Iodide. To 1 g of iodoform add 5 ml of sodium arsenite solution (made by dissolving 2.5 g of arsenic oxide and 5.5 ml of sodium hydroxide in 25 ml of water). The test tube is warmed for 5 minutes at 60-65° in a water bath and the mixture diluted with water. The oily drops which separate are methylene iodide. Look up the density and refractive index of the iodide. 

The pulp is first steeped in an aqueous solution of sodium hydroxide (17 18%), which causes the fibers to swell and converts the cellulose to sodium cellulosate, commonly called alkali cellulose or white crumb. After steeping, the swollen mass is pressed to obtain a precise ratio of alkali to cellulose and then shredded to provide adequate surface area for uniform reaction in subsequent process steps. The alkali cellulose is aged under controlled conditions of time and temperature to depolymerize the cellulose by oxidation to the desired DP prior to reacting with carbon disulfide to form sodium cellulose xanthate. The xanthate, which is a yellow to orange crumb, is dissolved in dilute sodium hydroxide to yield a viscous orange-colored solution called viscose. The solution is filtered, deaerated, and ripened to the desired coagulation point (called salt index) appropriate for spinning. 

Figure 31 displays the influence of sodium hydroxide concentration on the power-law index for each of the polymer solutions examined in Figure 30. At a given polymer concentration, the power-law index significantly increased as sodium hydroxide concentration was increased to 1 wt%. The rate of change of the power-law index with sodium hydroxide concentration was greatly reduced at sodium hydroxide concentrations greater than 1 wt%. These results indicate, considering the rod-like shape of xanthan chains, that the hydrodynamic radius of the polymer is significantly...

Figure 31. Effect of sodium hydroxide concentration on the power-law index of Flocon 4800 solutions.

The buffer index can be easily expressed as a function of the pH value and of some parameters related to the buffer. From a general standpoint, let s consider a solution containing Ca mol/L of hydrochloric acid, Cb mol/L of sodium hydroxide, and the analytical concentration C mol/L of the weak acid HA. Before writing the relations that must be satisfied, it is important to notice that the simultaneous presence of sodium hydroxide and weak acid HA results in the formation of the weak base... 

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