Calcium crimson

Calcium Green (2c), Calcium Orange (2d), and Calcium Crimson (2e) have been developed by Molecular Probes, Inc. they are suitable for fluorescence lifetime imaging of calcium.(71)... 

Abbreviations-. BCECF, 2, 7 -bii(2-carboxyethyl)-5(and 6)-carboxyfluorescein [Ru(bpy)2(dcbpy)J 2+, Bis(2,2 -b pyridine)(2,2 -bipyridine-4,4 dicarboxyHc acid)ruthenium(U) BOZ, Benzoxazine C., Carboxy CaC, Calcium Crimson CaG, Calcium Green CaO, Calcium Orange MgG, Magnesium Green SNAFL, seminaphtofluorescein SNARF, seminaphtorhodafluor. 

Figure 14. Absorption (top) and emission (bottom) spectra for Calcium Green, Calcium Orange and Calcium Crimson at various calcium concentrations.

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. 

The alkaline earth metals can be detected in burning compounds by the colors that they give to flames. Calcium burns orange-red, strontium crimson, and barium yellow-green. Fireworks are often made from their salts (typically nitrates and chlorates, because the anions then provide an additional supply of oxygen) together with magnesium powder. 

However, when small amounts of damp S and calcium hypochlorite are mixed, a brilliant crimson flash is observed accompanied by the scattering of molten burning S (Ref 9)... 

In a glass-stoppered, wide-mouth bottle cooled by ice water are placed 35 g. (0.42 mole) of thiophene (p. 73) and 50 cc. of benzene (Note 1). With constant shaking (Note 2), and cooling when necessary, 75 g. (0.35 mole) of yellow mercuric oxide and 109 g. (0.43 mole) of iodine are added alternately in small amounts during a period of fifteen to twenty minutes. The yellow mercuric oxide changes to crimson mercuric iodide. The mixture is filtered, and the residue is washed with three 25-cc. portions of ether. The ether-benzene filtrate is shaken with a dilute solution of sodium thiosulfate to remove excess iodine and then dried over 5 g. of calcium chloride and filtered. The ether and benzene are removed by distillation on a steam bath (Note 3), and the residue is fractionally distilled under reduced pressure. Iodothiophene distils at 73°/15 mm. 8o-8i°/20 mm. 90-94°/34 38 mm. The yield is 63-66 g. (72-75 per cent of the theoretical amount) (Note 4). If the iodothiophene is still colored by traces of iodine, the color may be removed by shaking with a small amount of mercuric oxide. 

A table showing the colours imparted to the flame by salts of different metals is given in Section V.2(3). Carry out flame tests with the chlorides of sodium, potassium, calcium, strontium, and barium and record the colours you observe. Repeat the test with a mixture of sodium and potassium chlorides. The yellow colouration due to the sodium masks that of the potassium. View the flame through two thicknesses of cobalt glass the yellow sodium colour is absorbed and the potassium flame appears crimson. 

Nitro-l(or 3)-methylphenarsazinic acid, formed by oxidising the preceding compomid, crystallises from a mixture of acetic aedd and dilute hydrochloric acid in yellow needles, unmdted at 308 C. It is insoluble in water and only sparingly soluble in acetic acid. The calcium and barium salts form pale yellow needles, and the salts of the heavy metals are amorphous. The sodium salt forms crimson nealles. 

Lustrous, silver-white surface (when freshly cut) face-centered cubic structure below 300 C. Ignites in air when finely divided, then burns with crimson flame. Much harder than sodium, but softer than aluminum or magnesium. Acquires bluish-gray tarnish on exposure to moist air. dj° 1.54. mp 85C. bp 1440. Electrical resistivity at 20 3.5 ohm cm. Brinell hardness 17. Heat of combustion 15l.9cal/g. sp ht (0-100 ) 0,149 cal/g. Considerably less reactive than sodium. E (aq) CaJ + /Ca —2.87 V. Reacts with water, alcohols, and dd acids with evolution of hydrogen. Reacts with halogens. Dissolves in liquid ammonia to form a blue soln. Contact with alkali hydroxides or carbonates may cause detonation. Bums in air. Calcium salts impart brick red color to a flame. Insol in and inert towards benzene, kerosene. 

Anilin may be recognized by the following reactions (1.) With a nitrate and HaSO<, a red color. (3.) Cold HaSOi does not color it alone on addition of potassium dichromate, a fine blue color is produced, which, on dilution with water, passes to violet and, if not diluted, to black. (8.) With calcium hypochlorite, a violet color. (4J Heated with cupric chlorate, a black color. (5.) Heated with mercuric chlorid, a deep crimson color. (0.) In very... 

Three of the alkaline earth metals can be identified by flame tests. Calcium produces a scarlet color, while strontium produces a crimson color. Barium, which if present in a sample can mask the colors of both calcium and strontium, produces a yellow-green color. 

Finely divided metal ignites in air. It bums with a crimson flame. It ignites at ordinary temperature only in finely divided form and when the air is moist. It reacts with water to form calcium hydroxide and hydrogen. The reaction is much less violent than with sodium. 

Crimson toner n. Azo pigment produced by coupling 4-aminotoluene-3-sulfonic acid with j -oxynaphthoic acid, followed by conversion to the calcium lake. 

Main ingredient for the manufacture of the madder lake pigments known to painters as rose madder and alizarin crimson. Used as a staining agent in biological research stains free calcium and certain calcium compoimds. Also used commercially as ared textile dye and, notably, is still the colour for French military cloth. Derivatives are commonly used as indicators of specific free ions and as pH indicators. 

Wash the sample in a solvent (benzene, oxylene, etc.) to remove all hydrocarbons. Rinse the sample in distilled water to remove salt crystals. Crush the sample and mix with enough 37% hydrochloric acid to form a slurry. Dip a platinum wire into the slurry and insert the wire into the flame of a Bunsen burner. Note the color of the flame calcium will emit an orange flame of short duration barium wiU emit a green flame of relatively long duration strontium will emit a crimson flame of relatively long duration. 

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