Pioneering Works

As mentioned already in Sect. 2.5, in 1971 Flanigenet al. [112] presented a study on IR bands observed with pure zeolite powders embedded in KBr or Csl pellets. Spectra were obtained in the wavenumber range below 1200 cm (or in some 

Flanigen et al. [112], published spectra of a series of zeolites, viz., X,Y (FAU), A (LTA), gismondine, PI (GIS), mordenite (MOR), L (LTL), Omega (MAZ), and zeolites W [philillipsite-related, D, G, R, S, T (for the three-letter acronyms, cf. [235] and for the other abbreviations [236]). They interpreted the framework vibration bands in terms of internal and external lattice vibration modes. 

The suggestions of band assignments to framework vibrations advanced in Refs. [112,114] were based on earlier IR investigations of silica and non-zeolitic aluminosilicate frameworks [238, 239]. These assignments are illustrated in Fig. 11. 

The two main categories of bands observed in mid infrared, i.e., intra-tetrahedral and inter-tetrahedral vibrations, are indicated by (1) solid and (2) broken lines, respectively. 

The most prominent bands ascribed to intra-tetrahedral modes were assiuned to occur in the ranges from (ij) 1250 to 950 cm k (i2) 790 to 650 cm, and (ij) 500 to 420 cm. Proposed assigmnents were as follows (cf. also Table 1 T=framework cation, e.g.. Si or Al)  

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When a system is not in equilibrium, the mathematical description of fluctuations about some time-dependent ensemble average can become much more complicated than in the equilibrium case. However, starting with the pioneering work of Einstein on Brownian motion in 1905, considerable progress has been made in understanding time-dependent fluctuation phenomena in fluids. Modem treatments of this topic may be found in the texts by Keizer [21] and by van Kampen [22]. Nevertheless, the non-equilibrium theory is not yet at the same level of rigour or development as the equilibrium theory. Here we will discuss the theory of Brownian motion since it illustrates a number of important issues that appear in more general theories. 

The first classical trajectory study of iinimoleciilar decomposition and intramolecular motion for realistic anhannonic molecular Hamiltonians was perfonned by Bunker [12,13], Both intrinsic RRKM and non-RRKM dynamics was observed in these studies. Since this pioneering work, there have been numerous additional studies [9,k7,30,M,M, ai d from which two distinct types of intramolecular motion, chaotic and quasiperiodic [14], have been identified. Both are depicted in figure A3,12,7. Chaotic vibrational motion is not regular as predicted by tire nonnal-mode model and, instead, there is energy transfer between the modes. If all the modes of the molecule participate in the chaotic motion and energy flow is sufficiently rapid, an initial microcanonical ensemble is maintained as the molecule dissociates and RRKM behaviour is observed [9], For non-random excitation initial apparent non-RRKM behaviour is observed, but at longer times a microcanonical ensemble of states is fonned and the probability of decomposition becomes that of RRKM theory. 

The state of nitric acid in g8-ioo% sulphuric acid In this section the pioneering work of Hantzsch will several times he mentioned. That later techniques made it necessary to modify his conclusions should not be allowed to obscure the great originality of his approach since investigations using these media provided the most compelling evidence for the existence of the nitronium ion. 

Fischer was the foremost or game chemist of the late nineteenth century He won the 1902 Nobel Prize in chemistry for his pioneering work in carbohydrate and protein chemistry... 

Animals accumulate cholesterol from then diet but are also able to biosynthesize It from acetate The pioneering work that identified the key intermediates m the com plicated pathway of cholesterol biosynthesis was carried out by Konrad Bloch (Harvard) and Feodor Lynen (Munich) corecipients of the 1964 Nobel Prize for physiology or... 

Table 2.5, based on the pioneer work of Davies, DeWitt and Emmett, ... 

In their pioneer work, Brunauer and Emmett adopted the value a (Ar) = 13-8 for the molecular area of argon, by insertion of the liquid density Pi in the standard equation (2.27). The same figure was recommended by McClellan and Harnsberger " as a result of their comprehensive survey of the literature, already referred to. These workers noted that the recorded values of a (based on a (N2) = 16 2 A ) extended over the wide range 10-19 A, and concluded that the area occupied per molecule of argon in the completed monolayer varied from one adsorbent to another. 

Following the pioneer work of Beebe in 1945, the adsorption of krypton at 77 K has come into widespread use for the determination of relatively small surface areas because its saturation vapour pressure is rather low (p° 2Torr). Consequently the dead space correction for unadsorbed gas is small enough to permit the measurement of quite small adsorption with reasonable precision. Estimates of specific surface as low as 10 cm g" have been reported. Unfortunately, however, there are some complications in the interpretation of the adsorption isotherm. 

In the pioneer work of Foster the correction due to film thinning had to be neglected, but with the coming of the BET and related methods for the evaluation of specific surface, it became possible to estimate the thickness of the adsorbed film on the walls. A number of procedures have been devised for the calculation of pore size distribution, in which the adsorption contribution is allowed for. All of them are necessarily somewhat tedious and require close attention to detail, and at some stage or another involve the assumption of a pore model. The model-less method of Brunauer and his colleagues represents an attempt to postpone the introduction of a model to a late stage in the calculations. 

Some pioneering work has been done on the effect of particle size on mouthfeel and texture perception (31). When particles of food materials are smaller than 0.1 ]lni they impart no sense of substance and the consumer calls the product watery. Particles of 0.1—3.0 ]lni are sensed as a smooth rich fluid, but when the particles exceed 3 ]lni the food is perceived as chalky or powdery. By controlling particle size, deskable creaminess can be obtained (32). 

Fischer-Tropsch Process. The Hterature on the hydrogenation of carbon monoxide dates back to 1902 when the synthesis of methane from synthesis gas over a nickel catalyst was reported (17). In 1923, F. Fischer and H. Tropsch reported the formation of a mixture of organic compounds they called synthol by reaction of synthesis gas over alkalized iron turnings at 10—15 MPa (99—150 atm) and 400—450°C (18). This mixture contained mostly oxygenated compounds, but also contained a small amount of alkanes and alkenes. Further study of the reaction at 0.7 MPa (6.9 atm) revealed that low pressure favored olefinic and paraffinic hydrocarbons and minimized oxygenates, but at this pressure the reaction rate was very low. Because of their pioneering work on catalytic hydrocarbon synthesis, this class of reactions became known as the Fischer-Tropsch (FT) synthesis. 

Organic fluorine compounds were first prepared in the latter part of the nineteenth century. Pioneer work by the Belgian chemist, F. Swarts, led to observations that antimony(Ill) fluoride reacts with organic compounds having activated carbon—chlorine bonds to form the corresponding carbon—fluorine bonds. Preparation of fluorinated compounds was faciUtated by fluorinations with antimony(Ill) fluoride containing antimony(V) haUdes as a reaction catalyst. 

Ethanol (1) is the most widely used antianxiety agent. In the 1950s, the pioneering work of Berger on the muscle relaxant mephenesin [59-47-17, (71), led to the identification of meprobamate (24) as an effective agent for the treatment of anxiety. 

The correlation for based on experimental data has been weU researched. The pioneering work was carried out in 1958 and a correlation with different impeller types and tank sizes was developed (5) ... 

Most processes in use in the 1990s make pyridines by condensation of ammonia with aldehydes or ketones either in the vapor phase or in the Hquid phase. These processes are based on the pioneering work of Chichibabin (3). Commercial practice of that process was not reali2ed until some 50 years after its discovery (74,75). 

Phase Behavior. One of the pioneering works detailing the phase behavior of ternary systems of carbon dioxide was presented ia the early 1950s (12) and consists of a compendium of the solubiHties of over 260 compounds ia Hquid (21—26°C) carbon dioxide. This work contains 268 phase diagrams for ternary systems. Although the data reported are for Hquid CO2 at its vapor pressure, they yield a first approximation to solubiHties that may be encountered ia the supercritical region. Various additional sources of data are also available (1,4,7,13). 

Diels-Alder Reactions. The important dimerization between 1,3-dienes and a wide variety of dienoplules to produce cyclohexene derivatives was discovered in 1928 by Otto Diels and Kurt Alder. In 1950 they won the Nobel prize for their pioneering work. Butadiene has to be in the j -cis form in order to participate in these concerted reactions. Typical examples of reaction products from the reaction between butadiene and maleic anhydride (1), or cyclopentadiene (2), or itself (3), are <7 -1,2,3,6-tetrahydrophthaHc anhydride [27813-21 -4] 5-vinyl-2-norbomene [3048-64-4], and 4-vinyl-1-cyclohexene [100-40-3], respectively. 

In this pioneering work Schmid 67HCA2244) studied a large collection of examples of... 

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