Fresh-cut

If a compound has been recrystallised from petrol, benzene, etc.y some freshly cut shavings of clean paraffin wax should be added to the calcium chloride in (A) or to the sodium hydroxide in D, The surface of the wax absorbs organic solvent vapours (particularly the hydrocarbons) and the last trace of such solvents is thus readily removed from the recrystallised material. 

The following alternative procedure is recommended and it possesses the advantage that the same tube may be used for many sodium fusions. Support a Pyrex test tube (150 X 12 mm.) vertically in a clamp lined with asbestos cloth or with sheet cork. Place a cube (ca. 4 mm. side = 0 04 g.) of freshly cut sodium in the tube and heat the latter imtil the sodium vapour rises 4 5 cm. in the test-tube. Drop a small amount (about 0-05 g.) of the substance, preferably portionwise, directly into the sodium vapour CAUTION there may be a slight explosion) then heat the tube to redness for about 1 minute. Allow the test tube to cool, add 3-4 ml. of methyl alcohol to decompose any unreacted sodium, then halffill the tube with distilled water and boil gently for a few minutes. Filter and use the clear, colourless filtrate for the various tests detailed below. Keep the test-tube for sodium fusions it will usually become discoloured and should be cleaned from time to time with a little scouring powder. 

Sodium test. Treat 1 ml. of the compound with a amall thin slice of freshly cut sodium (handle with the tonga or with a penknife) in a small, dry test-tube (75 X 10 mm. or 100 X 12 mm.). Observe whether hydrogen is evolved and the sodium reacts. (If the compound is suspected to contain water, dry it first with a little anhydrous calcium or magnesium sulphate.)... 

Strontium is softer than calcium and decomposes in water more vigorously. It does not absorb nitrogen below 380oC. It should be kept under kerosene to prevent oxidation. Freshly cut strontium has a silvery appearance, but rapidly turns a yellowish color with the formation of the oxide. The finely divided metal ignites spontaneously in air. Volatile strontium salts impart a beautiful crimson color to flames, and these salts are used in pyrotechnics and in the production of flares. Natural strontium is a mixture of four stable isotopes. 

A new form of coated abrasive has been developed that consists of tiny aggregates of abrasive material in the form of hoUow spheres. As these spheres break down in use, fresh cutting grains are exposed this maintains cut-rate and keeps power low (44). 

Sodium is a soft, malleable soHd readily cut with a knife or extmded as wire. It is commonly coated with a layer of white sodium monoxide, carbonate, or hydroxide, depending on the degree and kind of atmospheric exposure. In a strictiy anhydrous iaert atmosphere, the freshly cut surface has a faintiy pink, bright metallic luster. Liquid sodium ia such an atmosphere looks much like mercury. Both Hquid and soHd oxidize ia air, but traces of moisture appear to be required for the reaction to proceed. Oxidation of the Hquid is accelerated by an iacrease ia temperature, or by iacreased velocity of sodium through an air or oxygen environment. 

Properties. Thallium is grayish white, heavy, and soft. When freshly cut, it has a metallic luster that quickly dulls to a bluish gray tinge like that of lead. A heavy oxide cmst forms on the metal surface when in contact with air for several days. The metal has a close-packed hexagonal lattice below 230°C, at which point it is transformed to a body-centered cubic lattice. At high pressures, thallium transforms to a face-centered cubic form. The triple point between the three phases is at 110°C and 3000 MPa (30 kbar). The physical properties of thallium are summarized in Table 1. 

The moisture content of freshly cut wood varies between species and portions of the tree. Between species, it can be 30—70% on a total weight basis (65) commonly, it is 45—50%. Within a tree, the heartwood generally has lower moisture content than the sapwood. For hardwood species, this difference is usually small for softwood species such as Douglas-fir, the difference can be as great as 30% for heartwood compared with 50% for sapwood. 

Also purified by adding 2g NaBH4 to 1.5L butanol, gently bubbling with argon and refluxing for 1 day at 50°. Then added 2g of freshly cut sodium (washed with butanol) and refluxed for 1 day. Distd and the middle fraction collected [Jou and Freeman J Phys Chem 81 909 I977. ... 

The contact angles of water and adhesive resin on wood are higher in the case of freshly harvested wood compared to stored chips. This means that the surface of particles from this fresh wood is more hydrophobic. This influences the wetting and the penetration negatively and with this the gluability. Reason for this lower wettability of freshly harvested wood is a higher content of some wood chemical components, or wood extractives, as has been determined by water extraction. This result, however, must not be confused with the better wettability of a freshly cut surface, independently if it is freshly harvested or stored wood. 

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. 

In blood or tissues, this reaction is catalyzed by an enzyme called catalase (Figure 11.13). When 3% hydrogen peroxide is used to treat a fresh cut or wound, oxygen gas is given off rapidly. The function of catalase in the body is to prevent the build-up of hydrogen peroxide, a powerful oxidizing agent. 

B. 2,5-Heptanedione. Methanolic sodium methoxide [Methanol, sodium salt] is prepared by cautiously adding small pieces of freshly cut sodium (5.67 g., 0.247 mole) to 200 ml. of cold methanol (Note 3) in a 500-ml., three-nccked flask equipped with a mechanical stirrer, a... 

The initial surface, with freshly cut grooves, gave much higher figures than case (1). The nature of the surface will have a marked effect on the physical form of the bubble and the area actually in contact with the surface, as shown in Figure 9.51. 

FIGURE 1.60 All the alkali metals are soft, reactive, silvery metals. Sodium is kept under mineral oil to protect it from air, and a freshly cut surface soon becomes covered with the oxide. 

C. Active magnesium. A 200-ml., three-necked, round-bottomed flask is equipped with a Teflon-coated magnetic stirring bar, stopper, rubber septum, and condenser connected to an argon inlet (Note 6). The flask is charged with 1.5 g. (0.038 mole) of freshly cut potassium (Notes 7 and 8), 2.01 g. (0.0211 mole) of anhydrous magnesium chloride (Note 9), 3.55 g. (0.0214 mole) of anhydrous potassium iodide (Note 10), and 50 ml. of tetrahydrofu-ran (Note 11). The mixture is stirred vigorously (Note 12) and... 

C22-0112. A 250-mg sample of CO2 collected from a small piece of wood at an archaeological site gave 1020 counts over a 24-hour period. In the same counting apparatus, 1.00 g of CO2 from freshly cut wood gave 18,400 counts in 20 hours. What age does this give for the site ... 

Not-senescent and fresh-cut plants are almost devoid of degradation products like pheophytins and pheophorbides because chlorophylls associated with caro-... 

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