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One procedure

One procedure makes use of a box on whose silk screen bottom powdered desiccant has been placed, usually lithium chloride. The box is positioned 1-2 mm above the surface, and the rate of gain in weight is measured for the film-free and the film-covered surface. The rate of water uptake is reported as u = m/fA, or in g/sec cm. This is taken to be proportional to - Cd)/R, where Ch, and Cd are the concentrations of water vapor in equilibrium with water and with the desiccant, respectively, and R is the diffusional resistance across the gap between the surface and the screen. Qualitatively, R can be regarded as actually being the sum of a series of resistances corresponding to the various diffusion gradients present ... [Pg.146]

Retrosynthetic path e in Scheme 2.2 requires a regioselective oxidation of an o-nitrostyrene to the corresponding phenylacetaldehyde. This transformation has been accomplished hy Wacker oxidation carried out in such a way as to ensure the desired regioselectivity. The required o-nitrostyrenes can be prepared by Heck vinylation. One procedure for oxidation uses 1,3-propaiiediol to trap the product as a l,3-dioxane[15]. These can then be hydrogenated over Rh/C and cyclized by treatment with dilute HCl,... [Pg.16]

Commercial washing soda contains approximately 30-40% w/w Na2C03. One procedure for the quantitative analysis of washing soda contains the following instructions ... [Pg.363]

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). [Pg.330]

The vanadium alloy is purified and consoHdated by one of two procedures, as shown in the flow diagram of the entire aluminothermic reduction process presented in Figure 1. In one procedure, the brittle alloy is cmshed and heated in a vacuum at 1790°C to sublime most of the aluminum, oxygen, and other impurities. The aluminum faciHtates removal of the oxygen, which is the feature that makes this process superior to the calcium process. Further purification and consoHdation of the metal is accompHshed by electron-beam melting of pressed compacts of the vanadium sponge. [Pg.383]

Group Contribution Methods. It has been shown that many macroscopic physical properties, ie, those derived from experimental measurements of bulk solutions or substances, can be related to specific constituents of individual molecules. These constituents, or functional groups, are usually composed of commonly found combinations of atoms. One procedure for correlating functional groups to a property is as foUows. (/) A set of... [Pg.248]

The optimum measurements are those taken in the unit test. Figure 30-15 provides one procedure for identifying which measurements should oe taken within the plant. [Pg.2564]

The methods, which allow in one procedure of analysis to overcome, for example, most pesticides which are used in agricultural practice in the present time, get development and introduction in practice. The contribution of the Ukrainian scientists in field of chromatographic analysis of Persistent Organic Pollutants (POPs, chlorinated hydrocarbons, PCB s) and supertoxicants, such as PCDDs, is estimated. [Pg.65]

Chemical incompatibility charts can help in organizing available data on the incompatibilities existing between expected mixtures. Frurip (Frurip et ah, 1997) gives one procedure for developing a chemical compatibility chart while describing some of the tools available. CCPS G-13 also provides a table of known incompatibility hazards. [Pg.22]

The principal elements of document control are illustrated in Figure 5.5. This process provides for bringing existing documents under control, for controlling the preparation of new documents and for changing approved and issued documents. Each process could represent a procedure or a form. The processes may differ depending on the type of documents and organizations involved in its preparation, approval, publication, and use. One procedure may cater for all the processes but you may need several. [Pg.286]

Whether you have one procedure or twenty to address this requirement you need to cover all types of equipment as well as test software if you use it. Some of the requirements of this section may need to be addressed in procedures developed for other purposes, such as the requirement for determination of measurements. [Pg.399]

You may only need one procedure that covers all the requirements but this is not always practical. The provisions you make for specific quality records should be included in the procedures for controlling the activity being recorded. For example, provisions for inspection records should be included in the inspection procedures, provisions for design review records should be included in the design review procedure. Within such procedures you should provide the forms (or content requirements for the records), the identification, collection/submission provisions, the indexing and filing provisions. It may be more practical to cover the storage, disposal, and retention provisions in separate procedures because they may not be type-dependent. Where each department retains its own records, these provisions may vary and therefore warrant separate procedures. [Pg.503]

Ensure that the correct amount of aeration gas is injected along the standpipes. One procedure is to vary the aeration flow until the maximum slide valve differential is observed. [Pg.241]

One procedure is to use test specimens in the form of discs which can be rotated at the desired speed while either wholly or partly immersed in the testing solution, and Freeman and Tracy described a device of this sort in a contribution to the ASTM Symposium on Corrosion Testing Procedures. With their apparatus the specimen discs were mounted on horizontal shafts and were partially immersed in the testing solution. [Pg.996]

Discussion. One procedure is based upon the reaction between chlorate and iodide in the presence of concentrated hydrochloric acid ... [Pg.394]

There can be no set standard or measurement for all types of filth and filth elements, nor can any one procedure be employed, any one set of circumstances considered, or any one kind of evaluation applied. In any case, however, it is of prime importance that a thorough study of method precede manipulation furthermore, it is highly desirable that the operator have sufficient knowledge of production and storage conditions to draw logical and supportable conclusions from the filth elements recorded. Obviously, degree of infestation or rot could not be expected to follow with mathematical exactitude the constant curves found in other sciences. [Pg.63]

A number of techniques have been used to cool substances to low temperatures. Often, the process is done in steps one procedure is used to cool to a certain temperature, then a second cools to still lower temperatures, and so on. [Pg.184]

How do we describe the behavior of real gases that do not obey the ideal gas law A common procedure in chemistry is to suppose that the term on the right-hand side of an equation (such as nRT in PV = nRT of the ideal gas law) is just the leading (and predominant) term of a more complicated expression. Thus, to extend the ideal gas law to real gases, one procedure is to write... [Pg.289]

Only one procedure in this category emerged from the present survey. Thus treatment of 1,2-benzenediamine (372) with 3,3-bis(trifluoromethyl)-5-oxazolinone (373, R = H) in ethyl acetate containing a trace of acetic acid at room temperature for a short time afforded 2(l//)-quinoxalinone (374, R = H) in 92% yield 3-methyl- (374, R = Me), 3-isopropyl- (374, R = Pr"), 3-phenyl- (374, R = Ph), and 3-benzyl-2(l//)-quinoxalinone (374, R = CH2Ph) were made similarly in 60-80% yield. ... [Pg.51]

Only one procedure has been reported recently within this category. Thus 7-chloro-l-methyl-5-phenyl-2,3-dihydro-lH-benzodiazepin-2-one 4-oxide (437) with dimethyl acetylenedicarboxylate in methylene chloride at 20° C for 3 days gave a separable mixmre of the primary tricyclic adduct, dimethyl lO-chloro-6-oxo-llb-phenyl-5,6,7, 1 lb-tetrahydroisoxazolo[2,3-t/] [ l,4]benzodiazepine-1,2-dicarboxylate (438), and its rearrangement product, 6-chloro-4-(2-methoxalyl-2-methoxycarbonyl-l-phenylvinyl)-l-methyl-3,4-dihydro-2(lT0-quinoxalinone (439) each product afforded 6-chloro-l-methyl-2(l//)-quinoxalinone (440) on refluxing in ethanol (see also Section 1.7.13). However, the final quinoxaline (440) was best obtained in 75% yield) by simply heating the initial substrate (437) and dimethyl... [Pg.59]

Recently, this problem has been approached by reverting to reading the color of the bilirubin directly. This used to be called an "Icterus Index", in which the color of the serum was compared to a dilute dichromate solution (39). However, the new approach has been to use two wavelengths. This can be used in either of two different procedures. In one procedure the reading is made at the peak for bilirubin which is at 453 nm and at an isosbestic point for hemoglobin (40). The effect on the reading due to hemoglobin is subtracted from the bilirubin value. Commercial instruments based on this principle have not been successful. [Pg.131]

The composition of the enol ethers trimethylsilyl prepared from an enolate mixture reflects the enolate composition. If the enolate formation can be done with high regio-selection, the corresponding trimethylsilyl enol ether can be obtained in high purity. If not, the silyl enol ether mixture must be separated. Trimethylsilyl enol ethers can be prepared directly from ketones. One procedure involves reaction with trimethylsilyl... [Pg.15]

Reduction of (3-hydroxy ketones through chelated TSs favors. yy -l,3-diols. Boron chelates have been exploited to achieve this stereoselectivity.129 One procedure involves in situ generation of diethylmethoxyboron, which then forms a chelate with the (3-hydroxyketone. Reduction with NaBH4 leads to the vyn-diol.130... [Pg.412]

Fluorine substituents can also be introduced via diazonium ions. One procedure is to isolate aryl diazonium tetrafluoroborates. These decompose thermally to give aryl fluorides.106 Called the Schiemann reaction, it probably involves formation of an aryl cation that abstracts fluoride ion from the tetrafluoroborate anion.107... [Pg.1031]

The equivalent to allylic oxidation of alkenes, but with allylic transposition of the carbon-carbon double bond, can be carried out by an indirect oxidative process involving addition of an electrophilic arylselenenyl reagent, followed by oxidative elimination of selenium. In one procedure, addition of an arylselenenyl halide is followed by solvolysis and oxidative elimination. [Pg.1126]


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One-at-a-time procedure

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One-pot multicomponent reaction experimental procedure

One-pot procedure

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