Effect of amines

EFFECTS OF AMINES IN OXIDATION OF HYDROQUINONE WITH HYDROGEN PEROXIDE CATALYZED BY COPPER(H)... 

Initiation Mechanism and Structural Effects of Amine and Peroxide... 

Less attention has been paid to the ROOH-amine system, but we [34] have investigated the effect of amine... 

Table 8.3 Effect of Amines on Tacticity of Poly(methacrylic acid) at 60 DC90...

An old sample of acrolein (2 years) was stored in a fridge next to a bottle of dimethylamine. It detonated spontaneously. It was thought that aldehyde had polymerised under the effect of amine, which had diffused slowly through the caps. 

Yet another situation is observed in the 2,4-dinitrophenyl phosphate dianion. A significant effect of amines on the rate of decomposition is admittedly observed however, typical 2nd order kinetics, lower enthalpy of activation compared with spontaneous hydrolysis, and strongly negative AS values (see Table 3) indicate an Sn2(P) reaction. Surprisingly, the reaction rate remains unaffected by the basicity of the amine, even when its pKa value changes by 8 units. 

The results obtained with different amines cannot be explained merely on the effects of amine basicity. Thus, to obtain complete hydrogenation of Q to DHQ, the basicity has to be tailored by other factors such as the steric hindrance of the amine and its electronic interaction with the catalyst active sites this seems to be favored by the presence of an electron-rich aromatic ring. Of note, the positive effect of substituted aromatic amines, with a 49% DHQ yield being obtained for ethylanilines, is independent of the substituent position of the alkyl group. 

Several studies have been dedicated to the application of amine-modified carbon nano tubes (CNTs) as solid sorbents for C02 separation [65-69]. Industrial grade CNTs have been functionalized with tetraethylenepentamine (TEPA) by Liu et al. [65], and the effects of amine loadings on the C02 uptake, heat of adsorption, and adsorbent regenerability were investi-... 

Amiri AP, Haghighi ASLA, Ehsani MR (2007) Alkanolamines foaming tendency Effect of amine mixing, amine degradation and gas flow rate. Farayandno 8 2-7... 

Politzer, P., L. Abrahmsen, and P. Sjoberg. 1984. The Effects of Amine and Nitro Substituents upon the Electrostatic Potential of an Aromatic Ring. J. Am. Chem. Soc. 106, 855. 

As expected, the tighter ion pair (RNH , K+) exhibits the larger microwave effect. As an extension of this work, and in order to gain further insight, the effect of amine substituents was studied [99] in the reaction with ethyl benzoate (Eq. (47) and Tab. 3.21). 

To overcome the suppression effect of amines in the determination of ammonia, Hampson [56] investigated the effect of nitrite ions added either as nitrite or as nitrous acid. Figure 5.2 indicates that very considerable suppression by nitrite does occur, although it is not as strong as with any of the amines. Again, it is not great so long as the nitrite N concentration is less than the ammonia N concentration, but rapidly increases as the nitrite concentration exceeds the ammonia concentration. In fact, the nitrite modified method was found to be satisfactory in open seawater samples and polluted estuary waters. 

Effect of amine-modified C11SO4 on gold-bearing sulphide flotation from carbonaceous refractory ore... 

Figure 23.3 Effect of amine on Ta/Nb flotation from complex ore.

The ore used in this example contained a mixture of pyrochlore and columbite as the major niobium minerals. The tantalum is mainly associated with columbite. The major gangue minerals present in this ore were soda and potassium feldspars with small amounts of mica and quartz. Beneficiation of this ore using cationic flotation, normally employed for flotation of niobium, was not applicable for this particular ore, since most of the mica and feldspar floated with the niobium and tantalum. The effect of amine on Ta/Nb flotation is illustrated in Figure 23.9. The selectivity between Ta/Nb and gangue minerals using a cationic collector was very poor. 

Figure 23.9 Effect of amine acetate on the flotation of individual minerals.

Seki T, Kanbayashi H, Nagao T, Chono S, Tomita M, Hayashi M, Tabata Y, Morimoto K (2005) Effect of aminated gelatin on the nasal absorption of insulin in rats. Biol Pharm Bull 28 510-514. 

Figure 4.10 shows the effect of additive concentration on the separation of clen-buterol enantiomers on a polysaccharide-based chiral stationary phase [79]. The peak shapes were dramatically improved by adding an amine additive and the separation time was also reduced from 14 to 7 min when 1.0% amine was added to the mobile phase. Phinney and Sander [100] investigated the effect of amine additives using chiral stationary phases having either a macrocyclic glycopeptide or a... 

Poulson, E. and Robson, J.M. (1963) The effect of amine oxidase inhibitors on pregnancy./ Endocrinol 27 147—155. 

Such a mechanism explains why the inhibiting effect of amines decrease as the extent of the surface increases. Such a mechanism is unlikely in the inhibition of ethyl ether oxidation since there is no correlation between the acidity of the surface of the vessel and the ability of amines to inhibit the reaction (28). 

This paper is concerned with the effect of amines on intermediates formed during the oxidation of simple organic molecules. Amines were added first to two systems in which peroxides are known to be formed in high yield to see whether they have any effect on the kinetics of the later reactions between the fuel and oxygen secondly, amines were added to two peroxides under conditions where the amines act as inhibitors of gas-phase oxidation processes. 

The beneficial effects of amine A-oxide promoters are well documented in the example given in Equation (1). While the aromatized product 12 instead of the PKR product was obtained from the reaction of diethylacetylene 10 and compound 11 under thermal conditions, the desired PKR product 13 was formed only by the aid of amine A-oxide. 

Fig. 7. Effect of amine/Rh ratio on product rates ( ) methanol ( ) ethylene glycol. Reaction conditions 75 ml sulfolane, 3 mmol Rh, 544 atm, H2/CO = 1, 240 C, 4 hr (109). Upper graph is for l,4-diazabicyclo[2.2.2]octane (dabco) lower graph is for Af-methylmor-pholine.

Additional information about the effect of amine structure and solvent on the steric course of the reaction of amines with acetylenecarboxylic esters has recently been reported by Huisgen [93]. 

Figure 3. (a) Schematic of functionalized zeolite beta, (b) Conversion of PYC over functionalized zeolite, (c) Poisoning effect of amines on zeolite. 

Table II. Effect of Amine Basicity on Product Distribution ...

Figure 2. Effect of amine concentration on heptanal hydrogenation...

The above discussion has shown that the effects of amine basicity and concentration on catalytic activity are consistent with Equilibrium 3. No explanation has been presented for the increased hydrogenation activity of species II as compared with the amine-free hydrido carbonyl (species III). The data in Table IV and the first-order dependence of aldehyde provide the basis for such an explanation. 

As shown in Figure 3, a positive p-value (+0.92) was observed in the hydrogenation of substituted benzaldehydes, giving strong support to the postulation by Heil and Marko that the rate determining step in the formation of alcohol (Mechanism 2) is the hydride addition step. It is therefore suggested that coordination of amine to rhodium increases the hydridic character of the Rh-H bond, much the same as is postulated in cobalt-tributylphosphine complexation (20). The differing effect of amine on rhodium (promoter) and on cobalt (inhibitor) is attributed to the more hydridic nature of a Rh-H bond as compared with the very protonic HCo(CO)4. Addition of amines to HCo(CO)4 results in formation of inactive species similar to I. 

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