Melting point, sealed tube

Obtain a melting point capillary tube. One end of the tube will be sealed. The tube is packed with solid in the following way ... 

An alternative technique for preparing the glass bells follows heat the midsection of an open-ended melting point capillary tube and then draw the glass to form a smaller capillary section. This section is then broken approximately in the middle and each open end is sealed. The appropriate length for the bell is then broken off. Thus, two bells are obtained, one from each section. The sealing... 

In a generalized Adler method, one end of a capillary tube (1 Xl disposable micropipette, 3 cm long with an internal diameter of 0.2 mm) is flame sealed. The entire capillary tube is then quickly passed through a flame, and while warm, the open end is plunged into a reservoir containing the test chemical dissolved in chemotaxis medium. The liquid is drawn up into the capillary as it cools and the filled capillary is then withdrawn from the reservoir and inserted into a chemotaxis chamber, which is constructed by placing a U-shaped melting point capillary tube between a microscope slide and a coverslip (Fig. 1.2). The chamber is filled with an appropriate chemotaxis medium and inoculated with bacteria so that the final concentration is approximately 6 x 10 cells/ml. After a 1-h incubation, the capillary is removed from the chamber and the exterior rinsed with sterile water. The sealed end of the capillary is then broken and the contents are... 

Hold the tube horizontally and quickly seal this end in a micro-burner. Attach the tube (with the open end upwards) to a thermometer in the melting-point apparatus (Fig. i(c), p. 3) so that the trapped bubble of air in the capillary tube is below the surface of the bath-liquid. Now heat the bath, and take as the b.p. of the liquid that temperature at which the upper level of the bubble reaches the level of the surface of the batn liquid. 

Fig. 32). Using a fine pipette insert about i cm. length of the liquid into the bottom of the tube. Now place in the tube A a fine inverted melting-point tube B of about i mm. diameter, sealed at the upper end. Fasten the capillary tube to the ther- Fio. 32. mometer by means of a rubber band and place in a melting-point apparatus. Heat slowly until a stream of bubbles rises from the bottom... 

The acetyl group in aconitine may be eliminated in two other ways (a) by heating aconitine in sealed tubes with methyl alcohol, when methylbenzoylaconine, m.p. 210-1°, is formed, or (b) by heating the alkaloid at its melting-point, when pyraconitine, C32H43O9N, m.p. 167-5° (171°, Schulze), [a] ° — 112-2° (EtOH), is formed. The latter yields crystalline, laevorotatory salts, and on hydrolysis by alkalis affords benzoic acid and pyraconine, C2sH3gOgN, amorphous, [a]n — 91° (HgO), but yields a crystalline hydrochloride, B. HCl. 2-5H20, m.p. 154° (135°, Schulze), Md - 102° (HgO) (- 124-6°, Schulze). ... 

The isobomeol so formed melts at 212°, but the determination must be carried out in a sealed tube, as the melting-point is very dose to the temperature of sublimation. It is, however, very rarely that the isobomeol so prepared is free from impurities, and the melting-point will often be found to be as low as 203° to 205°. It is therefore necessary to pare derivatives of the isobomeol in order to identify it with certainty. Kie compound with bromal melts at 71° to 72°. Other compounds will be found mentioned under isobomeol . By dehydration by means of zinc chloride, isobomeol is easily converted into camphene, melting at about 49° to 50°. 

Chloro-lO-13-(di-N-2-chloroethvl)aminopropvl)lphenthiazine hydrochloride (1.8 g) is heated in a sealed tube for 4 hours at 140°C with a 290 g/l aqueous solution (9 cc) of monomethylpiperazine. The contents of the tube are treated with chloroform (40 cc). The aqueous layer is decanted and the chloroform layer is shaken with N hydrochloric acid (15 cc followed by 2 cc). The aqueous solution is treated with sodium hydroxide (d = 1.33, 10 cc) and chloroform (20 cc). After evaporation of the solvent, the base (1.5 g) is obtained. A solution of maleic acid (1 g) in ethanol (5 cc) is added and after recrystallization from water, 3-chloro-10-13-(4 -methyl-1 -piperazinvDpropyll phenothiazine dimaleate is obtained, melting point 228°C (inst.). 

The following description is taken from U.S. Patent 2,712,012 2.3 parts of clean sodium metal is dissolved in 50 parts of anhydrous methyl alcohol. 11.4 parts of 3-sulfanilamido-6-chloropyridazine is added and the mixture heated in a sealed tube 13 hours at 130° to 140°C. After the tube has cooled it is opened and the reaction mixture filtered, acidified with dilute acetic acid, then evaporated to dryness on the steam bath. The residue is dissolved in 80 parts of 5% sodium hydroxide, chilled and acidified with dilute acetic acid. The crude product is filtered and then recrystallized from water to give 3-sulfanilamido-6-methoxypyridazine of melting point 182° to 183°C. 

Aero Hydrolysis. A solution of kasugamycin hydrochloride (1.5 grams, 3.46 mmoles) dissolved in 15 ml. of 6N hydrochloric acid was heated at 105°C. for five hours in a sealed tube. The solution was condensed to 5 ml. under a reduced pressure and the addition of 50 ml. of ethyl alcohol afforded a crude solid overnight. It was recrystallized from aqueous ethyl alcohol, showing m.p. 246°-247°C. (dec.). It showed no depression in the mixed-melting point and completely identical infrared spectrum with d-inositol which was supplied by L. Anderson of the University of Wisconsin. The yield was 81% (503 mg., 2.79 mmoles). Anal Calcd. for CgH12Og C, 40.00 H, 6.71 O, 53.29 mol. wt., 180.16. Found C, 40.11 H, 6.67 O, 53.33 mol. wt., 180 (vapor pressure osmometer). 

Sodium-zinc alloys for phase diagram determination are prepared by melting the elements in glass tubes under H2. Samples of NaZn]3 are prepared by heating zinc for several hours above the melting point of NaZn, (557°C) with xs Na in alundum extraction thimbles with Nj or Ar in a steel bomb sealed with copper gaskets. Excess Na was removed by extraction with liq NH,. Both KZn,3 and KCd,2 were prepared in this manner. ... 

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