Preliminary experiments

Reaction temperature, K Agitation speed, rpm Catalyst loading, kgW Maleic acid methanol molar ratio Particle size, mm 

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The following alternative procedure is sometimes useful. Heat the amine with the theoretical quantity of benzoyl chloride (if the molecular weight is unknown, use an equal weight of benzoyl chloride in the preliminary experiment) to 100° for 20-30 minutes. Allow to cool, add excess of 5 per cent, sodium hydroxide solution and shake, if necessary,... 

Benzanilide and similar compounds are very slowly hydrolysed by concentrated hydrochloric acid hydrolysis is quite rapid with 60-70 per cent, sulphuric acid (for experimental details, see Section IV,52). In the preliminary experiment boil 0 5-1 Og. of the compound with 10-20 ml. of dilute sulphuric acid (1 1 by volume) imder reflux for 20-30 minutes. Dilute with 10ml.of water and filteroflfanyacid which may be precipitated if the carboxyhc acid is hquid and volatile, distil it directly from the reaction mixture. Render the residue alkaline and isolate the base as above. 

Statistical Characterization of Results from Preliminary Experiments... 

The choice of variables remaining with the operator, as stated before, is restricted and is usually confined to the selection of the phase system. Preliminary experiments must be carried out to identify the best phase system to be used for the particular analysis under consideration. The best phase system will be that which provides the greatest separation ratio for the critical pair of solutes and, at the same time, ensures a minimum value for the capacity factor of the last eluted solute. Unfortunately, at this time, theories that predict the optimum solvent system that will effect a particular separation are largely empirical and those that are available can be very approximate, to say the least. Nevertheless, there are commercially available experimental routines that help in the selection of the best phase system for LC analyses, the results from which can be evaluated by supporting computer software. The program may then suggest further routines based on the initial results and, by an iterative procedure, eventually provides an optimum phase system as defined by the computer software. 

Styrene-based polymer supports are produced by o/w suspension polymerization of styrene and divinylbenzene. Suspension polymerization is usually carried out by using a monomer-soluble initiator such as benzoperoxide (BPO) or 2,2-azo-bis-isobutylnitrile (AIBN) at a temperature of 55-85°C (19). A relatively high initiator concentration of 1-5% (w/w) based on the monomer is used. The time required for complete monomer conversion must be determined by preliminary experiments and is usually between 5 and 20 h, depending on the initiator concentration, the temperature, and the exact composition of the monomer mixture (11-18). 

Toluene was found to have low affinity toward silica gel and strongly promoted the adsorption of PMMA (12,14) on this material. Preliminary experiments revealed that toluene at least moderately promoted the adsorption of PMMA on several PS/DVB and DVB SEC gels. 

Preliminary experiments with contact-arc vaporization of graphite in a stream of He containing N2 or NH3 yielded nitrogen-containing products tentatively assigned to species such as C70N2 and (x = 2, 4, 6)... 

Preliminary experiments indicate that a-carboline is the major isomer formed in the reaction. The preparation of a mixture of a-(81.5%) and y-carboline (18.5%) from 3-o-nitrosophenylpyridine... 

Tast-gefuhl, n., -sum, m. sense of touch. Tastung, /. touching, etc. (see tasten). Tast-versuch, m. tentative experiment, preliminary experiment, -zirkel, m. calipers, tat, pret. (of tun) did, made, put. 

Preliminary experiments on the coupling of the chloride (lb) with digitoxigenin (3/ ,14,/ -dihydroxy-5/ -card-20(22)-enolide) in the presence of silver carbonate, led to gross decomposition of the halide, and it was suspected that, under the conditions of the experiments, the silver carbonate was causing elimination of hydrogen chloride. When, however, digitoxigenin was treated with an excess of lb in a small volume of... 

Bomb calorimeter. The heat flow, q, for the reaction is calculated from the temperature change multiplied by the heat capacity of the calorimeter, which is determined in a preliminary experiment... 

Preliminary experiments prove that the substitution pattern of the /V-aryl moiety of imine 1 is crucial for the stereoselectivity of this reaction. The 2-substituent on the aryl group is of special importance. Namely, introduction of a methoxy group leads to a considerable decrease of enantioselectivity compared to the corresponding 2-H derivative, probably due to disfavor-able coordination with the organolithium complex. In contrast, alkyl groups show the reverse effect along with increased bulkiness (e.g., Tabic 1, entries l-3a) but 2,6-dimethyl substitution provides lower ee values. Furthermore, the 4-substituent of the TV-aryl moiety is of minor importance for the stereoselectivity of the reaction [the Ar-phcnyl and the /V-(4-methoxyphenyl) derivatives give similar results], whereas a substituent in the 3-position results in lower stereoselectivities (e.g., Et, Cl, OCHj)41. 

Effects of solvent polarity, counter-anion nucleophilidty, temperature, and monomer concentration on the carbenium ion polymerization chemistry have been extensively studied29,36 38,49. Based on previous knowledge26"29 Me3Al was chosen because with this coinitiator undesired chain transfer to monomer processes are absent. Preliminary experiments showed that Et3Al coinitiator did not yield PaMeSt, possibly because the nuc-leophilicity of the counter-anion Et3AlQe is too high and thus termination by hydrida-tion is faster than propagation36. ... 

Rate coefficients have been determined for protodeboronation of benzene- and thiophene-boronic acids in a range of aqueous perchloric acid mixtures at temperatures between 25 and 90 °C630. First-order rate coefficients are given in Table 204, but not all of the rates were measured at the acidities indicated (see Table footnote), but were corrected to these making use of the linear relationship which was found, in preliminary experiments, to exist between log rate and H0. Similarly, the relative reactivities to thiophene-2-, thiophene-3-, and benzene-boronic acid (8.5 x 10s, 7.1 x 103, and 1.0, respectively) were obtained at an H0... 

The chemical similarity between lanthanide and actinide metals suggests that C2H I2 might also react with actinide metals. Preliminary experiments found no reaction between thorium or uranium metals and a THF solution of Plutonium and neptunium... 

The Pu(IV)-HS0u System. In the Pu(IV)-HS0i system, a series of preliminary experiments was necessary to establish the stoichiometry of the TTA extraction process with respect to [H+] and... 

While it is true, therefore, that a general method for analysis could be developed and used successfully for a number of applications based on previous knowledge, for those in which optimum performance is required it is advisable to carry out preliminary experiments in which the variables of ionization technique, polarity, cone-voltage, etc., as well as those of sample isolation, are investigated (see Section 5.1 above). 

Nva) nucleoamino adds Fmoc-Nva -OH (15) and Fmoc-Nva -OH (18). Both of these nucleoamino acids have now been synthesized regioselectively in good overall yields starting from the known pyroglutamic acid derivative 10 via the sequences shown in Scheme 5.2 [44]. Preliminary experiments have shown that these two nudeoamino acid derivatives can be incorporated into our SPPS without the need for protection of the exocyclic NH2 groups [45]. 

The high simple diastereoselectivities observed running the [4-1-3] cycloadditions raised the question concerning the induction of chirality. Preliminary experiments involving chiral menthyloxy Fischer carbenes 169 (R = (-)-men-thyl) resulted in the formation of the diastereomeric lactim ethers 173-1 and 173-2 in a 7 3 ratio, which could be separated by means of a crystallization. A final acidic hydrolysis gave the enantiomerically pure e-caprolactams 175 and ent-175 and the acyclic esters, respectively. No signs of racemization have been detected,Eqs. (18,19) [39b]. 

Preliminary experiments with electron-beam writing and ion-beam projection lithography have demonstrated that the S-layer may also be patterned by these techniques in the sub-lOO-nm range (nnpnblished resnlts). The combination of ion-beam projection lithography and S-layers as resist might become important in the near fntnre, since ion beams allow the transfer of smaller featnres into S-layer lattices compared to optical lithography. 

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