Colorants hygroscopicity

A soln of 130 (0.17 g, 0.34 mmol) and TFA (2.0 mL, 26 mmol) in CH2CI2 (4mL) was stirred at rt for 3h. The volatiles were removed in vacuo, and the residue was dissolved in H20 (15 mL). The resulting soln was frozen and lyophilized to give 131 as a mixture of diastereomers, and as a cream colored hygroscopic powder yield 151 mg (97%) mp 89-92°C. Attempted further purification via RP-chromatography on Sephadex LH-20, with H20 as the mobile phase, resulted in extensive hydrolysis to free glutamic acid and benzoin, as determined by isolation and coelution with authentic samples on TLC. 

PROP Orange colored hygroscopic powder. Sol in H2O sltly sol in EtOH. 

Appearance White to cream colored hygroscopic powder Ionic Character Nonionic Solubility in Water In all proportions Moisture 5% Maximum... 

White to buff-colored, hygroscopic, fine powder. Odorless or has not more than a slight amine-like odor. Insol in water, alcohol, benzene, chloroform, ether. 

Bnff to cream-colored hygroscopic powder- Acrid odor, growing stronger with age. Bulky, approx 3 ml/g, not free-... 

P, is a white or creamy colored, hygroscopic powder (4% water), m.p. 130 °C. It is nonsweet, acidic (pH 2.5-3.5), noncariogenic and suited for diabetics. The physiological energy content is 4-12 kJ/ g (different test methods). Digestion in the small intestine occurs randomly. 

Other Borohydrides. Potassium borohydride was formerly used in color reversal development of photographic film and was preferred over sodium borohydride because of its much lower hygroscopicity. Because other borohydrides are made from sodium borohydride, they are correspondingly more expensive. Generally their reducing properties are not sufficiently different to warrant the added cost. Zinc borohydride [17611-70-0] Zn(BH 2> however, has found many appHcations in stereoselective reductions. It is less basic than NaBH, but is not commercially available owing to poor thermal stabihty. It is usually prepared on site in an ether solvent. Zinc borohydride was initially appHed to stereoselective ketone reductions, especially in prostaglandin syntheses (36), and later to aldehydes, acid haHdes, and esters (37). 

Properties. Anhydrous aluminum chloride is a hygroscopic, white soHd that reacts with moisture ia air. Properties are shown ia Table 1. Commercial grades vary ia color from light yellow to light gray as a result of impurities. Crystal size is dependent upon method of manufacture. At atmospheric pressure, anhydrous aluminum chloride sublimes at 180°C as the dimer [13845-12-0] Al2Qg, which dissociates to the monomer beginning at... 

Liquid cycloahphatic amines and diamines have exacting purity and color standards. Almost all are sold to specification, not performance standards. Use as isocyanate precursors requites low water content criteria for these hygroscopic fluids, hence nitrogen blanketing is often specified for product sampling as well as storage and transport. 

Copper(II) sulfate monohydrate [10257-54-2] CuS04-H2 0, which is almost white in color, is hygroscopic and packaging must contain moisture barriers. This product is produced by dehydration of the pentahydrate at 120—150°C. Trituration of stoichiometric quantities of copper(II) oxide and sulfuric acid can be used to prepare a material of limited purity. The advantages of the monohydrate as opposed to the pentahydrate are lowered freight cost and quickness of solubilization. However, these advantages are offset by the dustiness of the product and probably less than one percent of copper sulfate is used in the monohydrate form. 

The process of textile print coloration can be divided into three steps. First, the colorant is appHed as pigment dispersion, dye dispersion, or dye solution from a vehicle caUed print paste or printing ink, containing in addition to the colorant such solutions or dispersions of chemicals as may be required by the colorant or textile substrate to improve and assist in dye solubUity, dispersion stabUity, pH, lubricity, hygroscopicity, rate of dye fixation to the substrate, and colorant-fiber bonding. The required viscosity characteristics of a print paste are achieved by addition of natural or synthetic thickening agents or by use of emulsions. 

Disadvantages of the phenolic resins are the necessary longer press times compared to UF-resins, and the dark color of the glue line and the board surface. There is also the possibility of a higher moisture pickup of the boards when stored at higher relative humidity due to the hygroscopicity of the high alkali content of the resin. 

Ml Thickener It is a coarse, granular material ranging in color from light tan to brown. Chemically, it is a coprecipitated A1 soap of naphthenic, oleic and palmitic acids in the approx ratio of 1 1 2. The three main disadvantages accruing from the properties of Ml thickener are (1) it is a critical wartime material since it is made from coconuts (2) it is extremely hygroscopic, and the presence of water decreases its ability to form a stable thickened fuel. In addition, the relatively large... 

Complex Preparation. Three complexes were isolated with nominal copper to pyridine ratios of 1 4, 1 2, and 1 1. The green solutions yielded either green (1 4 and 1 2) or yellow brown (1 1) hygroscopic powders. The complexes could be redissolved after isolation. Films prepared by evaporating the solutions were transparent, and of the same color as the powders. 

Reddish violet crystals hexagonal plates density 2.87g/cm3 melts at 1,152°C decomposes at 1,300°C shghtly soluble in water. The color of hexa-hydrates range from light-green to violet all are hygroscopic density 1.76 g/cm3 soluble in water and ethanol insoluble in ether dilute aqueous solutions are violet in color. 

Exists in two isomorphous forms, a- and 13-forms both modifications highly hygroscopic. The a-form is black hexagonal crystal density 5.58 g/cm turns dark green in air melts at 560°C disolves in water giving pink coloration. The a—forms sublimes in vacuo, partly forming an isomorous yellow modification—the anhydrous (3—form. 

Quinolines are hygroscopic and darken in color when exposed to light. 

Explosive B T No 21 (Victorite). A compn ptepd by mixing flour (18.8), sulfur (1.9) KCIO3 (75.1%) in a soln of resin (4.2%) in an org solv, and then removing the solv by evaporation. This process is designed to coat the expl particles with resin, thereby waterproofing them and reducing their, sensitivity. The product may also be dyed different colors. The compn was unsatisfactory for military application because of its sen si tivity, hygroscopicity low brisance Ref J.D. Hopper, PATR 481(1934)... 

Gadolinium Oxide, Gd203, mw 362.52 wh to cream-colored powder, sp gr 7.407 at 15/4°, mp 2330° hygroscopic and absorbing C02 from the air in sol in w sol in acids except HF. Used in nuclear reactor control sods, neutron shields, catalysts, dielectric ceramics, filament coatings, special glasses and as P... 

The product is a very pale yellow to cream-colored solid. It is hygroscopic and is soluble in liquid ammonia, with limited solubility and stability in acetonitrile, dimethyl sulfoxide, and dimethylformamide. Water or moisture from the air leads to disproportionation, and so the product must be stored under anhydrous... 

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