General procedure

A powerful technique in studying both adsorption and desorption rates is that of programmed desorption. The general procedure (see Refs. 36, 84) is to expose a clean metal filament or a surface to a known, low pressure of gas that flows steadily over it. The pressure may be quite low, for example, 10 mm Hg or less, so that even nonactivated adsorption can take some minutes for... 

Classical ion trajectory computer simulations based on the BCA are a series of evaluations of two-body collisions. The parameters involved in each collision are tire type of atoms of the projectile and the target atom, the kinetic energy of the projectile and the impact parameter. The general procedure for implementation of such computer simulations is as follows. All of the parameters involved in tlie calculation are defined the surface structure in tenns of the types of the constituent atoms, their positions in the surface and their themial vibration amplitude the projectile in tenns of the type of ion to be used, the incident beam direction and the initial kinetic energy the detector in tenns of the position, size and detection efficiency the type of potential fiinctions for possible collision pairs. 

The general procedure in a QSPR approach consists of three steps structure representation descriptor analysis and model building (see also Chapter X, Section 1.2 of the Handbook). 

Di- and poly-halogenated aliphatic hydrocarbons. No general procedure can be given for the preparation of derivatives of these compounds. Reliance must be placed upon their physical properties (b.p., density and refractive index) and upon any chemical reactions which they undergo. 

The above is a general procedure for preparing trialkyl orthophosphates. Similar yields are obtained for trimethyl phosphate, b.p. 62°/5 mm. triethyl phosphate, b.p. 75-5°/5 mm. tri-n-propyl phosphate, b.p. 107-5°/5 mm. tri-Mo-propyl phosphate, b.p. 83-5°/5 mm. tri-wo-butyl phosphate, b.p. 117°/5-5 mm. and tri- -amyl phosphate, b.p. 167-5°/5 mm. The alkyl phosphates are excellent alkylating agents for primary aromatic amines (see Section IV,41) they can also be ua for alkylating phenols (compare Sections IV,104-105). Trimethyl phosphate also finds application as a methylating agent for aliphatie alcohols (compare Section 111,58). 

The above simple experiments illustrate the more important properties of aliphatic acid chlorides. For characterisation, the general procedure is to hydrolyse the acid chloride by warming with dilute alkali solution, neutralise the resulting solution with dilute hydrochloric acid (phenol-phthalein), and evaporate to dryness on a water bath. The mixture of the sodium salt of the acid and sodium chloride thus obtained may be employed for the preparation of solid esters as detailed under Aliphatic Acids, Section 111,85. The anilide or p-toluidide may be prepared directly from the acid chloride (see (iii) above and Section III,85,i). 

A fairly general procedure consists in coupling a phenol or naphthol with a diazotised amine, reducing the product to an aminophenol or aminonaphthol, and oxidising the hydroxy compound with acid ferric chloride solution. This method is illustrated by the preparation of (3 (or 1 2)-naphthoquinone ... 

A careful consideration of the results of the above tests will provide much useful information and will indicate which of the foUowing general procedures should be apphed and the modifications which are necessary. Thus if nitrogen is absent, it is doubtful whether the separation for bases would be necessary. 

GENERAL PROCEDURE The Alcoholic alkaline solution is prepared by prolonged stirring of 8.8g (or 4.4g) of KOH pellets in 30mL of alcohol. The alkaline solution is placed in a round-bottom flask provided with a reflux condenser (microwave or conventional systems). Then 4.0g of Safrole (or eugenol) is added and the solution heated."... 

Anyway, there have been two very hot topics in chemistry lately clay microwaves. Both have been shown to do remarkable things in preparative organic chemistry. And this article Strike has [58], has combined both to produce some stunning reductive ami-nations of ketones to final amine products. The procedure involves mixing naked ketone, the amine, some clay and some NaBH4 in a beaker and zapping it in the microwave for only a couple of minutes. That s it. The general procedure is as follows ... 

Synthesis of Alkviamines. General Procedures. Method (A). The synthesis of p-phenethylamine is representative. A flame dried, nitrogen-flushed, 100 ml flask, equipped with a septum inlet, magnetic stirring bar and reflux condenser ivas cooled to 0°C. Sodium borohydride (9.5 mmol, 0.36 g) was placed in the flask followed by sequential addition of THF (13-15 ml) and BF3-Et20 (12 mmol, 1.5 ml) at 0°C. After the addition, the ice bath was removed and the contents were stirred at room temperature for 15 min. The solution... 

Alkvl Azides from Alkyl Bromides and Sodium Azide General procedure for the synthesis of alkyl azides. In a typical experiment, benzyl bromide (360 mg, 2.1 mmol) in petroleum ether (3 mL) and sodium azide (180 mg, 2.76 mmol) in water (3 mL) are admixed in a round-bottomed flask. To this stirred solution, pillared clay (100 mg) is added and the reaction mixture is refluxed with constant stirring at 90-100 C until all the starting material is consumed, as obsen/ed by thin layer chromatographv using pure hexane as solvent. The reaction is quenched with water and the product extracted into ether. The ether extracts are washed with water and the organic layer dried over sodium sulfate. The removal of solvent under reduced pressure affords the pure alkyl azides as confirmed by the spectral analysis. ... 

The above synthesis, although performed on a small scale, is easily scaled up to industrial size (French Pat. 2,669,922, CA 118 P6734U). It is a general procedure for substituting aryl-Br with -OMe or -OEt, giving us the possibility to produce other compounds from already known substances, e.g bromination of MDA yields 6-Br-MDA. This is converted by the above procedure to MMDA-2, 133, active at 25-50mg, 8-12 hrs. 

General Procedure - To a solution of 0.3 moles of sodium azide and 0.1 mole of mercuric acetate in 200mL of 50% aqueous tetra-... 

To a mixture of O.BB mol of anhydrous lithium chloride and 100 ml of OMSO was added a solution of 0.40 mol of the acetylenic tosylate (for a general procedure concerning the preparation of acetylenic tosylates, see Chapter VllI-3, Exp. 3) in IBO ml of DMSO. The flask was equipped for vacuum distillation (see Fig. 5). Between the receiver, which was cooled at -75°C, and the water-pump was placed a tube filled with KOH pellets. The apparatus was evacuated (10-20 mmHg) and the flask gradually heated until DMSO began to reflux in the column. The contents of... 

Since 1,2- to 1,6-difunctional openstarting materials for syntheses of three- to seven-membered heterocycies 1,2-heterocycles can be made from 1,2-difunctional compounds, e.g. olefins or dibromides 1,3-difunctional compounds, e.g. 1,3-dibromides or 1,3-dioxo compounds, can be converted into 1,3-heterocycles etc. 

Synthesis of large heterocycles usually involves condensation reactions of two difunctional molecules. Such molecules tend to polymerize. So far two special techniques have been described above to avoid this important side-reaaion , namely high dilution and use of templates. The general procedure to avoid polymerizations in reactions between difunctional molecules is, of course, the application of protecting groups as described in sections 4.1.2 and 2.6. 

The same general procedure was applied satisfactorily to the synthesis of 2-bromothiazoles using hydrogen bromide below 0°C (465, 507) (Table 11-29). 

Dehydrogenation of alkylbenzenes although useful m the industrial preparation of styrene is not a general procedure and is not well suited to the laboratory prepara tion of alkenylbenzenes In such cases an alkylbenzene is subjected to benzylic bromi nation (Section 11 12) and the resulting benzylic bromide is treated with base to effect dehydrohalogenation... 

After selection of a force field simulation program which is appropriate to a given problem, the general procedure is as follows ... 

Enolate Initiators. In principle, ester enolate anions should represent the ideal initiators for anionic polymeri2ation of alkyl methacrylates. Although general procedures have been developed for the preparation of a variety of alkaU metal enolate salts, many of these compounds are unstable except at low temperatures (67,102,103). Usehil initiating systems for acrylate polymeri2ation have been prepared from complexes of ester enolates with alkak metal alkoxides (104,105). 

Crystallization Method. Such methods as mechanical separation, preferential crystallisation, and substitution crystallisation procedures are included in this category. The preferential crystallisation method is the most popular. The general procedure is to inoculate a saturated solution of the racemic mixture with a seed of the desired enantiomer. Resolutions by this method have been reported for histidine (43), glutamic acid (44), DOPA (45), threonine (46), A/-acetyl phenylalanine (47), and others. In the case of glutamic acid, the method had been used for industrial manufacture (48). 

The equations and methods for determining viscosity vary greatly with the type of instmment, but in many cases calculations may be greatly simplified by calibration of the viscometer with a standard fluid, the viscosity of which is known for the conditions involved. General procedures for calibration measurement are given in ASTM D2196. The constant thus obtained is used with stress and shear rate terms to determine viscosity by equation 25, where the stress term may be torque, load, or deflection, and the shear rate may be in rpm, revolutions per second (rps), or s F... 

The thermal design of cooling towers follows the same general procedures already presented. Integration of equation 35 is usually done numerically using the appropriate software, mass-transfer coefficients, saturation enthalpies, etc. In mechanical-draft towers the air and water dows are both suppHed by machines, and hence dow rates are fixed. Under these conditions the design procedure is straightforward. 

Starch Esters. As with the starch ethers, a large number of starch esters have been prepared and patented, but only a few are manufactured and used commercially. Both inorganic and organic acid esters can, and have been, made. The latter are prepared by the same general procedure used to make starch ethers. 

The same general procedures of heating and cooling are foUowed in the case of soldering in a furnace, except that a piece of solder can be laid on the junction prior to insertion in the furnace. The solder melts and flows if the upper furnace temperature is properly set. The temperature should be set at ca 14—28°C (25—50°F) above the Hquidus temperature of the solder or at the manufacturer s recommended soldering temperature. 

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