Benzene carbide synthesis

We have developed solvothermal synthesis as an important method in research of metastable structures. In the benzene-thermal synthesis of nanocrystalline GaN at 280°C through the metathesis reaction of GaClj and U3N, the ultrahigh pressure rocksalt type GaN metastable phase, which was previously prepared at 37 GPa, was obtained at ambient condition [5]. Diamond crystallites were prepared from catalytic reduction of CCI4 by metallic sodium in an autoclave at 700°C (Fig.l) [6]. In our recent studies, diamond was also prepared via the solvothermal process. In the solvothermal catalytic metathesis reaction of carbides of transition metals and CX4 (X = F, Cl, Br) at 600-700°C, Raman spectrum of the prepared sample shows a sharp peak at 1330 cm" (Fig. 1), indicating existence of diamond. In another process, multiwalled carbon nanotubes were synthesized at 350°C by the solvothermal catalytic reaction of CgCle with metallic potassium (Fig. 2) [7]. 

X-ray structure of the mesitylene derivative was reported shortly afterward.11 This represented the second structurally characterized cluster containing an interstitial atom [the structure of FesC(CO)i5 having already been established]12 and the first example of a cluster with a completely encapsulated carbide atom. At the time that the synthesis of 2 was first reported, another paper described the synthesis of a cluster also obtained from 3 when heated to 150°C in either benzene or cyclohexane. Based on an estimation of the mass of this compound from a differential vapor pressure measurement, the authors suggested that this compound corresponded to Ru6(CO)18.13 It was subsequently noted from a comparison of vco IR data and a structural determination that this compound was in fact 2. 

Mechanochemical processing has been used to manufacture nanocrystalline powders of nitride and carbide ceramics. The majority of systems involve milling of the metal precursor with a source of carbon or nitrogen. The source of carbon or nitrogen has typically taken the form of the element itself. However, a variety of other reagents have also been used. For example, Zhang et al. reported the synthesis of titanium nitride by milling titanium metal with pyrazine in a benzene solution. 

Early observations of benzylic acetoxylation were made in the study of arene acetoxylation and biaryl coupling when toluene was used as a substrate. In 1966, the reaction between stoichiometric Pd(OAc)2 and toluene to give benzyl acetate as the major product was disclosed [72]. Two years later, acetoxylation of toluene with catalytic Pd salts was reported by Union Carbide by using phosphines or a combination of Sn(OAc)2, charcoal, and air as oxidant to give 96TONs [73]. Additional metal acetates such as KOAc are beneficial for the reaction [74]. These acetoxylation methods were further applied to other arenes [75] (e.g., benzene, cyclohexene) and the synthesis of benzyl diacetate [76] (a precursor to benzalde-hyde). 

Recently, the Yankee Atomic Electric Company, Environmental Laboratory, has determined the tritium levels in water samples from the environs of several nuclear generating facilities in the New England area by liquid scintillation analysis of high purity tritiated benzene prepared from the water samples to be quantified. A commercially available unit was utilized to facilitate the synthesis of benzene by reacting the water sample with calcium carbide to form tritiated acetylene which is subsequently trimerized on a vanadium catalyst to high purity tritiated benzene. 

Ethylene from cracking of the alkane gas mixtures or the naphtha fraction can be directly polymerized or converted into useful monomers. (Alternatively, the ethane fraction in natural gas can also be converted to ethylene for that purpose). These include ethylene oxide (which in turn can be used to make ethylene glycol), vinyl acetate, and vinyl chloride. The same is true of the propylene fi action, which can be converted into vinyl chloride and to ethyl benzene (used to make styrene). The catalytic reformate has a high aromatic fi action, usually referred to as BTX because it is rich in benzene, toluene, and xylene, that provides key raw materials for the synthesis of aromatic polymers. These include p-xylene for polyesters, o-xylene for phthalic anhydride, and benzene for the manufacture of styrene and polystyrene. When coal is used as the feedstock, it can be converted into water gas (carbon monoxide and hydrogen), which can in turn be used as a raw material in monomer synthesis. Alternatively, acetylene derived from the coal via the carbide route can also be used to synthesize the monomers. Commonly used feedstock and a simplified diagram of the possible conversion routes to the common plastics are shown in Figure 2.1. 

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