The Influence of Additives

The effect of an additional site of complexation, as well as the influence of additional stereogenic centers, was demonstrated with the diastereomeric sulfoxides 2 A -2D40. Addition of the racemic,... 

Following three phase transformations [951] (>298 K), NH C decomposition begins [915] in the solid phase at 423 K but only becomes extensive well above the melting point ( 440 K). Decomposition with the evolution of N20 and H20 from the melt is first order [952,953] (E = 153—163 kJ mole-1), the mechanism suggested involving intermediate nitramide formation. Other proposed schemes have identified NOj [954] or the radical NH2NO [955] (<473 K) as possible participants. Studies [956,957] have been made of the influence of additives on NH C decomposition. 

Studies of the influence of additives on rates of salt decompositions are often directed towards the formulation or confirmation of a mechanism... 

Wang BX, Peng XF (1994) Experimental investigation of liquid forced-convection heat transfer through micro-channels. Int J Heat Mass Transfer 37 73-82 Wasekar VM, Manglik RM (2002) The influence of additive molecular weight and ionic nature on the pool boiling performance of aqueous surfactant solutions. Int J Heat Mass Transfer 45 483-493... 

Thus it is clear from both the remarkable constant selectivity to methane and the influence of addition of methane on the selectivities to CHCIF2 and CH2F2, that the serial reaction mechanism has to be modified in order to explain the observed phenomena. Therefore, more measurements will be performed in order to determine the adsorption of CFCs on the metal surface and the influence of other products, such as CH2F2 and HCl on the catalyst performance [11]. 

Several supported metalhc catalysts were evalrrated for the selective hydrogenolysis of glycerol. Initially, the reactions were performed tmder acidic conditions in order to promote the formation of 1,3-PDO. Rutheniirm-based catalysts were found to be the most active catalysts but significant amount of tmdesired products resulted from C-C cleavages were detected. On the contrary, Rh/C catalysts were found selective to C-O cleavages. As far as the selectivity to 1,3-PDO was concerned, we previously reported that the addition of iron salts in the medium improved the l,3-PDO/l,2-PDO selectivity (11). A systematic study on the influence of additives was therefore carried out in the present investigation. Mineral and organic acids were evaluated for this purpose (Table 35.1). 

The appropriate amount of biocide carrier composition needed to yield a specified dry film concentration of biocide was added to a fixed quantity of waterborne acrylic paint and premixed using a high-speed disperser. This dispersion was then transferred to a Silverson-type mixer to obtain a finer dispersion. At this stage the influence of addition of silica or zeolite on the physical/mechanical properties of the paint film was assessed, though only minor changes in properties were noted, which could be eliminated by appropriate adjustments to the paint formulation. 

Todini, O. and Hulshoff Pol, L., Anaerobic degradation of benzaldehyde in methanogenic granular sludge the influence of additional substrates, Appl. Microbiol. Biotechnol., 38,417-420, 1992. 

The influence of additional functional groups on the complexing abilities of 1,3-xyly 1-crown ethers [28] and [50]—[53] and binaphthyl-crown ethers... 

Model studies on single crystal surfaces are also helpful in developing an understanding of the effects of surface additives on catalyst performance. Electronegative, electroneutral (i.e. metals) and electropositive additives can all be studied. The influence of additives on the bond strengths and structure of... 

The results show that basic alkylphosphines are especially suitable. The ligand should be sterically demanding, but tri-f-butylphosphine (entry 8) is obviously too bulky. An ideal ligand seems to be tri-f-propylphosphine (entries 6 and 7). Unfortunately, the water-soluble ligands TPPMS (entries 2 and 3) and TPPTS do not work in this reaction, also the carbene ligand bis(mesitylene)imidazolium chloride (entry 12) has only a low activity. The influence of additives like maleic anhydride (MA) and 1,3-divinyltetra-methyldisiloxane (dvds) is negligible. 

Cohen-Atiya and Mandler have also found that the extent of discharging process is significantly decreased in aprotic solutions and in the absence of oxygen. However, the influence of additional functional groups located at the other end of thiol molecules on the discharging process is still not fully understood. Possibly, such groups (e.g. carboxylic) affect accessibility of water to the electrode surface. 

In a recent study by Sun et al. (2007) of 20 vol% oil-in-water emulsions stabilized by 2 wt% whey protein isolate (WPI), the influence of addition of incompatible xanthan gum (XG) was investigated at different concentrations. It was demonstrated that polysaccharide addition had no significant effect on the average droplet size (d32). But emulsion microstructure and creaming behaviour indicated that the degree of flocculation was a sensitive function of XG concentration with no XG present, there was no flocculation, for 0.02-0.15 wt% XG, there was a limited... 

The influence of additional nitrogen atoms in the azines sometimes allows new reactions. An example of this is that of nucleophilic displacement of a cyano group, as in (561) — (562) this does not normally occur in the pyridine series, but is analogous to a reaction of acyl cyanides (RCOCN). 

This last reaction (RM) enables us to understand the formation of products containing 3 carbon atoms (glycerol, 1,2-propanediol) from glucitol (sorbitol) but is always in competition with the two other ones (DOH, RC). The ratio of these three reactions, determining the conversion selectivity, depend widely on the copper origin (Raney, deposited on a support, impurities, activation process). So, we studied the influence of additives deposited on Raney copper on these reaction selectivities. 

The influence of additives was investigated after changing the conditions of catalyst activation especially after modifying the calcination temperature. It can be seen in Table 3 that the selectivity varies very much with this activation step and also that the final result depends on the nature of the additive ... 

We now try to explain the influence of additives. Addition of small quantities of dichloroethane leads to curves with two inflections, one near n = 7 and another near n = 16-20. It is also the shape of copolymer prepared without additive. 

Because systematic variations in selectivity with reactivity are commonly quite mild for reactions of carbocations with n-nucleophiles, and practically absent for 71-nucleophiles or hydride donors, many nucleophiles can be characterized by constant N and s values. These are valuable in correlating and predicting reactivities toward benzhydryl cations, a wide structural variety of other electrophiles and, to a good approximation, substrates reacting by an Sn2 mechanism. There are certainly failures in extending these relationships to too wide a variation of carbocation and nucleophile structures, but there is a sufficient framework of regular behavior for the influence of additional factors such as steric effects to be rationally examined as deviations from the norm. Thus comparisons between benzhydryl and trityl cations reveal quite different steric effects for reactions with hydroxylic solvents and alkenes, or even with different halide ions... 

Si3N4 by itself is colourless due to the big gap between the valence and the conduction band (3.5-5.5 eV) [526], But normally Si3N4 ceramics are more or less grey, because of the influence of additions, impurities and sintering conditions. 

The comparison of CMC data in distilled vs. hard river water shows that the decrease in CMC with hardness has the order anionics cationics nonionics (Rosen et al., 1996). Hardness increases the dependence of the CMC on alkyl carbon chain length of CnE0mS04, indicating that in hard water the influence of additional carbon atoms is the same for CnE0mS04 as for CnEOm surfactants (Rosen et al., 1996). The influence of ionic strength on micellization of nonionic surfactants is due to a salting out effect of the hydro-phobic moiety of the surfactant molecule (Carala et al., 1994). 

In order to evaluate the influence of additional methyl groups at the para-position of the SAr groups, we also reacted Cul under analogous conditions with bis(p-tolylthio)methane in acetonitrile in a 2 1 molar ratio (Scheme 8). An X-ray diffraction study revealed that colorless polymer 10 of general formula [ Cu4((jl3-I)4 p-p-TolSCI 12ST0I) 2] is isostructural with 9, crystallizing in the monoclinic space group C2/c. 

One approach, which has proved revealing in the case of 9-carbena-fluorene and which may be generally applicable, is to examine the influence of additives which can deactivate electronically excited carbenes without undergoing reaction themselves (e.g. hexafluoro-benzene) or which react preferentially with carbenes of a particular spin state (e.g. oxygen and butadiene, which are both thought to react preferentially with triplet carbenes). The technique is analogous to well-... 

Very recently, an extensive study on the influence of additives, oxidants, and solvents on the MTO-catalyzed oxidation of a-pinene was published (entries 12-15) [54], By following the reaction in time and varying the amount of nitrogen base (in this case 4-tert-butylpyridine) at both 0°C and 25°C, it was found that the amount of a-pinene oxide increases rapidly in the beginning but decreases later on in the reaction, indicating that the oxidation is relatively fast compared to the hydrolysis of the epoxide. The best conditions use 20 equivalents of 4-tert-butylpyridine and a reaction temperature of 0°C to give an a-pinene oxide yield of 85% after 1.5 h (entry 12). 

Oehme et al. investigated the influence of addition orders for the catalyst system Nd(OCOR)3/TIBA/EASC [163]. The catalyst components were mixed at 25 °C and aged for 30 min at the same temperature. Catalyst activities and molar masses decreased in the order (1) > (2) > (3) ... 

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