Preparation for Use

Any dust, fibers, or particulate material between the inner and outer members of a joint or stopcock can cause jamming and/or excessive wear on glass or scratch Teflon. 

If you examine the cleaned plug from an old burette s stopcock (especially one from a freshman chemistry lab), you will see a lot of scratching and wear on either side of the hole. This wear is caused by particulate matter collected in the hole (see Fig. 3.32). In time, this wear circumscribes the entire plug, causing a leak that nothing can stop save replacement of the entire stopcock. Frequent cleaning (often not provided to freshmen chemistry burettes) can prevent unnecessary wear and subsequent problems. 

Teflon items (Teflon stopcock plugs, rotary valve plugs, and Teflon sleeves) should be wiped off with some acetone (using a Kimwipe) before being assembled for use. 

---

AH intrinsic germanium metal sold is specified to be N-type with a resistivity of at least 40 H-cm at 25°C or 50 H-cm at 20°C. Germanium metal prepared for use in infrared optics is usuaHy specified to be N-type with a resistivity of 4-40 Hem, to be stress-free and fine annealed, and to have certain minimum transmission (or maximum absorption) characteristics in the 3—5 or 8—12 pm wavelength ranges. Either polycrystaHine or single-crystal material is specified. 

Mesitylene is converted to a dye iatermediate, 2,4,6-trimethyl aniline [88-05-1] (mesidine), via nitration to l,3,5-trimethyl-2-nittobenzene [603-71-4] followed by reduction, eg, catalytic hydrogenation (38). Trinitromesitylene has been prepared for use ia high temperature tolerant explosives (39). The use of mesitylene to scavenge contaminant NO from an effluent gas stream has been patented (40). 

Specifications and standards for various vitamin E forms and preparations for use in pharmaceutical appHcations ate given in the United States Pharmacopeia (52). AH products should contain not less than 96.0% or more than 102.0% of the appropriate form. The products must be labeled to indicate both the chemical and stereochemical forms contained in the product. 

Low viscosity urethane polymers have been prepared from castor od and polymeric isocyanates (82). These low mix viscosity systems are extremely usehd for potting electrical components where fast penetration without air voids, and fast dispensing cycles are desirable. Very low viscosity urethane systems containing castor polyols have been prepared for use in reclaiming water-logged buried telephone cable and for encapsulating telephone cable sphces (83—86). 

Coppet(II) oxide [1317-38-0] CuO, is found in nature as the black triclinic tenorite [1317-92-6] or the cubic or tetrahedral paramelaconite [71276-37 ]. Commercially available copper(II) oxide is generally black and dense although a brown material of low bulk density can be prepared by decomposition of the carbonate or hydroxide at around 300°C, or by the hydrolysis of hot copper salt solutions with sodium hydroxide. The black product of commerce is most often prepared by evaporation of Cu(NH2)4C02 solutions (35) or by precipitation of copper(II) oxide from hot ammonia solutions by addition of sodium hydroxide. An extremely fine (10—20 nm) copper(II) oxide has been prepared for use as a precursor in superconductors (36). 

Cosmetic shaving products are preparations for use before, during, or after shaving. 

Dental Stones. Dental stones, produced from gypsum, are sold as dry powders in sealed containers. They are prepared for use by mixing with water, in proportions recommended by the manufacturer. 

The carboxamidomethyl ester was prepared for use in peptide synthesis. It is formed from the cesium salt of an A-protected amino acid and a-chloroacetamide (60-85% yield). It is cleaved with 0.5 M NaOH or NaHCOa in DMF/H2O. It is stable to the conditions required to remove BOC, Cbz, Fmoc, and r-butyl esters. It cannot be selectively cleaved in the presence of a benzyl ester of aspartic acid. ... 

If 1,4-dihydroestradiol 3-methyl ether is being prepared for use as an intermediate in the preparation of 1,4-dihydroestrone 3-methyl ether, it is most... 

Deca/octahydro 6-alkyloxazolo /-fused quinolines 17 were prepared and evaluated as dopaminergics (87EUP1). A series of linearly annelated 8-alkyl-deca/ octahydrooxazoloquinolines 18 and their salts were prepared for use as dopamine D2-agonists and hypertensive agents. The rran.s-( )-l-propyl-6-oxodecahydro-quinoline was brominated, then treated with urea in methanol to give the 2-amino... 

Catalysis by an Acidic Resin (5).- The resin (Dowex-50,200-400 mesh or comparable sulfonated polystyrene) is prepared for use by suspending it in dilute sulfuric acid, followed by many washings with water (and decantation of the wash), and air drying for several days. 

Many of the indicator solutions are available from commercial suppliers already prepared for use. 

Hydroxyquinoline is an almost colourless, crystalline solid, m.p. 75-76 °C it is almost insoluble in water. The reagent is prepared for use in either of the following ways. 

GEP2811780 79JCS(P1)1120 80EUP9384 80JCS(P1)1139], Reduction of the carbonyl function of 529 to provide 530 was best achieved with lithium aluminium hydride in 1,2-dimethoxyethane. Dehydrogenation of 530 over palladium on charcoal afforded 531. They were prepared for use as muscle relaxants and bronchodilators (Scheme 110). 

There are many preparations of diazonium salts listed in Organic Syntheses, but they are always prepared for use in other reactions. We do not list them here, but under reactions in which they are used. The preparation of aliphatic diazo compounds can be found in OS III, 392 IV, 424. See also OS VI, 840. 

Faye GH 1971) Canadian Mines Branch Technical Bulletin TB139 Molybdenum Ore PR-i its characterization and preparation for use as a standard reference material. 

A blend of Wilsonville recycle solvent (75 weight percent) and 1,2,3,4-tetrahydronaphthalene (25 weight percent) was prepared for use as the solvent in experiments simulating the second process step, which would use hydrogenated solvent. Analyses and distillation data for this solvent are also given in Table 2. Tetralin boils below 232 C and was collected in the light oil distillation fraction during product workup. 

Ferric oxide prepared for use as an inorganic colouring agent for rubbers. The colour varies according to type, brick-red, orange, bluish-red, etc. 

The complete range of pigments may be conveniently divided into three main groups on the basis of their chemical constitution and mode of preparation for use ... 

The structures of the dimethylsiloxane block copolymers and respective parent homopolymers prepared for use as positive, bilevel resist materials are shown in Figure 1. Most copolymers were synthesized with >10 wt % silicon. The selection of PDMSX block length and novolac chemical composition proved to be the two most critical variables in achieving adequate resolution. 

Ashwood-Smith, M.J. (1980). Stability of frozen microsome preparations for use in the Ames Salmonella mutagenicity assay. Mutation Res. 69 199-200. 

The peyote cactus is prepared for use by cutting the crown and drying it into buttons, which retain potency for a long time. They are then eaten or made into a tea for drinking. Purified mescaline crystals are dissolved and taken orally or injected. Doses vary considerably, ranging from 4 to more than 30 buttons. 

In preparation for use as a surrogate vaccine, these peptides were synthesized as conjugates to tetanus toxoid, and in this form also competed with the 0-antigen polysaccharide for binding [104]. Whether these peptides will function as effective immunogenic mimics will likely depend on their propensity to adopt the bioactive conformation in solution. A certain amount... 

---