Secondary product, definition

As can be seen in Figs. 3a and 3b phenol is clearly a primary product on both catalysts. On HY all the other compounds seem to be secondary products except the hydroxyacetophenones which could be formed at least partly as primary products. Compounds III, IV and V are formed only at high conversion. On HZ SMB, hydroxyacetophenones are definitely secondary products while para-acetoxyacetophenone is a primary product. Compounds IV and V are not formed in detectable amounts. Compounds VI and VII are formed in small quantities. 

Melanine, ammelide and cyanuric acid were not detected in the HCOOH extracts and the identification of s-triazines previously reported does not prove that s-triazines are indigenous. This kind of compound can easily be formed during the experimental and analytical procedures. Nevertheless, this last conclusion is not definitive. As pointed out by Stoks and Schwartz33, the carbonaceous chondrites are far from homogenous. Important variations from sample to sample exist, even if all these samples are fragments of the same chondrite. Moreover, and as previously reported, the sample treatment is of prime importance. It can lead to the formation of secondary products or liberate molecules unobservable after milder treatment. To conclude, it seems clear that nitrogen heterocycles are present in carbonaceous chondrites and that pyrimidine derivatives are less abundant than purine derivatives. 

An important preliminary remark must be made. In contrast to non-zeolite catalysts the heavy secondary products responsible for zeolite deactivation are not always polyaromatics. Indeed the pores of certain zeolites are too narrow to allow the formation of potyaromatic compounds and even to accommodate them [1]. This has caused some confusion in the relevant literature, certain authors using the word coke only for the polyaromatic compounds and others for all the secondary products, polyaromatic and non polyaromatic retained in or on the zeolite. Although the designation of non polyaromatic and sometimes simple molecules as "coke may appear surprising it is this latter definition that will be used here. Indeed the non polyaromatic molecules contributing with the polyaromatic ones to deactivation and often through similar modes we considered preferable to use the same term (coke) for all the secondary products responsible for zeolite deactivation [8]. 

Regarding the possible mechanism, notably, toluene, ethylbenzene and terf-butylbenzene are less reactive than benzene, which is not consistent with the expected order for an electrophilic aromatic substitutions, such as that found with the classic Fenton reagent. There are also other differences with respect to the Fenton chemistry. In particular, under biphase conditions the reaction is definitely more selective although comparisons are difficult due to the huge amount of data, sometimes inconsistent, on the Fenton system (for which most of the data have been obtained with the iron used in stoichiometric amounts) it seems that selectivities dose to those observed under biphase conditions are only attained at a conversion around of 1%. Furthermore, in the biphase system, only a negligible amount (<1%) of biphenyl was detected among secondary products, whereas in the classic Fenton oxidation this compound is formed by radical dimerization of hydroxycydohexadienyl radicals in typical yields ranging from 8 to 39%. 

In case of system expansion, other than in allocation, benefits attributed by usable secondary products or materials are calculated, which represent the saved environmental impact in another life cycle of the product. Quantification of these benefits depends primarily on the quality of the secondary product and the definition of its application. 

In 1958, Geiseler and Nagel31 reported the energetics of the chlorosulphonation reaction of n-dodecane (31) with a mixture of S02 and Cl2 (equation 14.) They reported that a mixture of primary and secondary sulphonyl chlorides were formed accompanied by liberation of 39.0 + 0.5 kcal mol-1. The ratio of primary (19) to (the other wise undefined mixture of isomeric) secondary products (32) was determined to be ca 1 11. However, in the absence of further study, we cannot determine how much this reaction is thermodynamically driven (e.g. sulphonyl chloride and free radical stabilities) versus kinetically driven (e.g. free radical reactivities). We will assume that the difference in heats of formation of all of the secondary sulphonyl chlorides are the same. That the difference of the heats of formation of the primary and secondary products is about 2 kcal mol-1 may be derived from values for a set of isomeric primary (n-) and secondary (i-) propyl derivatives shown in Table 8. From the long known and highly accurate heats of formation of liquid n-dodecane (31, — 83.9 kcal mol-1, Reference 3) and of gaseous S02 and HC1 (—70.9 and — 22.1 kcal mol-1, Cl2 equalling 0 by definition, all from Reference 12), we derive the heat of formation of any of the five different secondary n-dodecanesulphonyl chlorides (32) to be —171.9 kcal mol-1 and for the primary n-dodecane-1-sulphonyl chloride (19) a value of —169.9 kcal mol-1. 

The hitherto unknown cyclodimer 12 might be a secondary product formed by dimerization of 11. The search for absorptions associated with 12 in the spectrum of the deposit (Figure 6.1) was, however, unsuccessful. No peak could be definitely assigned to this elusive species, even after annealing the matrix and the disappearance of lines due to 11. Hence, if formed at all, only... 

However, there is no long-term project realized in the evolution of these functions and the significance of secondary products in many instances is not precise and definite. Secondary substances rather form a fund and may be used in different ways, depending on the opportunities. Hence, as in other fields evolution works like a tinkerer-a tinkererwho does not know exactly what he is going to produce, but uses whatever he finds around him. .. (Jacob 1977). 

Although many out of the hundreds of reactions in aqueous solution studied by pulse radiolysis are due to the secondary products such as OH-, there are also several hundred in which an oxidising agent is reduced by the solvated electron itself, before it has had time to react with the solvent, e.g., by addition e q -I- A" A" (cf. Section 1.2.3). In these reactions the solvated electron may be regarded as a distinct ionic entity, with a definite diffusion coefficient determined from the conductivity), and a radius r of about 3 A (calculated from the Stokes-Einstein equation. Section 1.2.3). The electron lies in a potential-energy trap ... 

The stable secondary products of the Maillard reaction, that are isolated from many different reaction mixtures and have known structures, can be generally assigned to a definite deoxyosone by a series of plausible reaction steps (enolization, elimination of water, retroaldol cleavage, substitution of an amino function for a hydroxy function etc.). 

It was anticipated all along that the vinylsilane residue could serve as a vinyl iodide surrogate. After protection of the C-14 secondary hydroxyl in 180 in the form of a triisopropylsilyl ether, the vinyltrimethylsilyl function can indeed be converted to the requisite vinyl iodide with AModosuccinimide (NIS) (see 180—>181, Scheme 43). Vinyl iodide 181 is produced stereospecifically with retention of the A17,18 double bond geometry. This transformation is stereospecific since the stereochemistry of the starting vinylsilane and the vinyl iodide product bear a definite relationship to each other.67b 75... 

Roentgen, definition of the, 248 Roentgen, W. C., discovery and investigation of x-rays by, 2, 9-12, 43 Nobel Prize awarded to, 2 production of secondary x-rays by, 12 x-ray absorption studies by, 11 x-ray papers of, 2... 

Changes in the composition of gaseous products as reaction proceeds may make definition of the fractional decomposition, a, difficult. For example, product CO and residual carbon may be capable of reducing a metallic oxide, particularly at high a and the catalytic properties of an accumulating solid product may result in promotion of secondary gas reactions. 

Zinc fertilizers made from recycled hazardous secondary materials. U.S. EPA promulgated a conditional exclusion from the definition of solid waste for hazardous secondary materials that are recycled to make zinc fertilizers or zinc fertilizer ingredients. Zinc, an important micronutrient for plants and animals, can be removed from zinc-rich manufacturing residue and used to produce zinc micronutrient fertilizer. A second conditional exclusion applies to the zinc fertilizer products made from these secondary materials. 

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