In order to gain strong insight into the surface chemistry of silica we have perform a thorough literature search. Our goal is to identify the pioneer research performed on silica and silica supported catalyst. Particular interest lies in silica-water-cobalt and silica-alcohol-cobalt systems. This study is both on macro and micro level so that a complete theoretical base can be established. From this theoretical knowledge, key areas to look upon will be identified and a design of experiments will be established. The goal is to develop a both efficient and effective product (catalyst) using a novel methodology developed from past research.
Silica Structure:
Fundamental studies by Stober [ ], Meyer and Heckerman [ ] , and Bering and Serpinskii [ ] indicate that silica surface consists of siloxane network in the bulk, while the hydroxyl groups are attached onto silicon atoms. However these groups are not equivalent in their adsorption or reaction behavior. Fig 1a represents a general arrangement on a silica surface. Belyakova et al. identifies that the number of hydroxyl (Silanol) group on different type of silica surfaces are same i.e. 4 -5 SiOH groups per nm2. Lange [ ] identifies that water associates with these silanol groups in two ways, by hydrogen bonding or by physically adsorbed. Dalton and Iler [ ] states that there is at least a monolyer of water immobilized on silanol groups due to hydrogen bonding, this “glassy layer” protects underlying silica network from foreign molecules. Klier and Zettlemoyer [ ] indicates that water sat “oxygen down” on silanol groups. De Boer and Vleeskens [ ] argued that around 120 oC in ambient air silica looses adsorbed water unless it is present in micropores which would otherwise tak...
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...ussion: Adsorption sites for salt as well as for alcohol are polar silanol groups (Fig 1c). As discussed earlier, alcohol is not adsorbed on all silanol groups (prefers isolated silanol group) and alcohol is more preferentially adsorbed than salt. So, anchorage of salt on the silica surface must be very distinct, reducing the possibility of irreducible mixed metal support formation. Also for substantial adsorption, silica gel has to be contacted with very concentrated salt-alcohol solution. In our opinion small amount of water cause ionization of alcohol which further induce ionization at silanol surface creating anionic sites suitable for esterification of ethoxy group. On the other hand, salt is mostly “associated” if the water is around 1-2% in the solution and the adsorbed salt will act as nucleation site for salt present mainly because of physical interaction.
The boiling point of the product was conducted with the silicone oil. Lastly, for each chemical test, three test tubes were prepared with 2-methylcyclohexanol, the product, and 1-decene in each test tube, and a drop of the reagent were added to test tubes. The percent yield was calculated to be 74.8% with 12.6g of the product obtained. This result showed that most of 2-methylcyclohexanol was successfully dehydrated and produced the product. The loss of the product could be due to the incomplete reaction or distillation and through washing and extraction of the product. The boiling point range resulted as 112oC to 118oC. This boiling point range revealed that it is acceptable because the literature boiling point range included possible products, which are 1-methylcyclohexene, 3-methylcyclohexene, and methylenecyclohexane, are 110 to 111oC, 104oC, and 102 to 103 oC. For the results of IR spectroscopy, 2-methylcyclocahnol showed peaks at 3300 cm-1 and 2930 cm-1, which indicated the presence of alcohol and alkane functional group. Then, the peak from the product showed the same peak at 2930 cm-1 but the absence of the other peak, which indicated the absence of the alcohol
The purpose of the experiment is to study the rate of reaction through varying of concentrations of a catalyst or temperatures with a constant pH, and through the data obtained the rate law, constants, and activation energies can be experimentally determined. The rate law determines how the speed of a reaction occurs thus allowing the study of the overall mechanism formation in reactions. In the general form of the rate law it is A + B C or r=k[A]x[B]y. The rate of reaction can be affected by the concentration such as A and B in the previous equation, order of reactions, and the rate constant with each species in an overall chemical reaction. As a result, the rate law must be determined experimentally. In general, in a multi-step reac...
The three butene products have been verified to elute in the following order: 1-butene, trans-2-butene, and cis-2-butene. Theory: The dehydration of 2-butanol, a secondary alcohol, progresses readily in the presence of a strong acid like concentrated sulfuric acid (H2SO4). The reaction is completed via the E1 mechanism. Initially, the hydroxyl group is a poor leaving group, but that is remedied by its protonation by the acid catalyst (H2SO4) converting it to a better leaving group, H2O. The loss of this water molecule results in a secondary carbocation intermediate that continues to form an alkene in an E1 elimination.
This paragraph will compare and discuss the crystal structure and chemistry between quartz (SiO2), iron phosphate (FePO4) and also looking into the α and β phase of FePO4. From the understanding of the given materials and crystal structure of both SiO2 and FePO4, both of the crystal are quartz-type crystal, the crystal arrangement are quite similar except for the difference in structural parameters tilt angle δ and bridging angle θ. This similarly carries on from the fact that both crystals had a α-β transition. However, from figure 2, the transition temperature for SiO2 and FePO4 are dramatically different, where one is at 846K while the other is 980K respectively. This is due to the tilt and bridging angle is lower than SiO2. Also from figure 2, we can show that both SiO2 and FePO4 thermal expansion in α phase are non-linear and control by angular variations and similarly no thermal expansion in β phase due to the lack
Michael P. Broadribb, C. (2006). Institution of Chemical Engineers . Retrieved July 26, 2010, from IChemE: http://cms.icheme.org/mainwebsite/resources/document/lpb192pg003.pdf
In order to separate the mixture of fluorene, o-toluic acid, and 1, 4-dibromobenzene, the previously learned techniques of extraction and crystallization are needed to perform the experiment. First, 10.0 mL of diethyl ether would be added to the mixture in a centrifuge tube (1) and shaken until the mixture completely dissolved (2). Diethyl ether is the best solvent for dissolving the mixture, because though it is a polar molecule, its ethyl groups make it a nonpolar solvent. The compounds, fluorene and 1, 4-dibromobenzene, are also nonpolar; therefore, it would be easier for it to be dissolved in this organic solvent.
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
Aerogel was discovered in the late 1930’s by chemist Samuel Stephens Kistler. He accomplished this by the process of supercritical fluid drying. A supercritical fluid is any substance at a temperature and pressure above its critical poi...
The solvent should be easily removed from the purified product, not react with the target substances, and should only dissolve the target substance near it’s boiling point, but none at freezing. A successful recrystallization uses minimum amount of solvent, and cools the solution slowly, if done to fast, many impurities will be left in the crystals. Using the correct solvent, in this case ice water and ethyl acetate, the impurities in the compound can be dissolved to obtain just the pure compound. A mixed solvent was used to control the solubility of the product. The product is soluble in ethanol an insoluble in water. Adding water reduced solubility and saturates the solution and then the crystals
This meeting between the two particles can only take place on the surface area of the material. If the surface area of the material is increased, the particles gather more space to collide with each other with force. With a large surface area, the particles will have more area to work on so the collision probability will be high. A catalyst is a separate substance to the ones you use in your experiment and is used to speed up the reaction between the reactants.
Sheikheldin, S. Y., Cardwell, T. J., Cattrall, R. W., Luque de Castro, M. D. and Kolev, S. D. (2000) Determination of Henry's Law Constants of Phenols by Pervaporation-Flow Injection Analysis. Environmental Science & Technology, 35(1), pp. 178-181.
...he pore space of a packed bed of glass beads as they dissolved into a flowing aqueous phase at the pore-scale. The same study was performed in different media such as estuarine sediments (Reeves and Chudek, 2001), silica gel (Zhang et al., 2002), rock fractures (Becker et al., 2003), and organic-rich soil cores (Simpson et al., 2007). In water and NAPL distributions, hydrocarbons such as fluorinated NAPLS have been used to distinguish NAPL from water and air and enhance the imaging contrast and quality. This idea has been implemented in evaluation of water and NAPL saturations in heterogeneous media (Zhang, 2006); and NAPL dissolution under water flushing (Zhang et al., 2007, 2008a). Another application of this technique is on evaluation of surfactant-enhanced remediation (Zhang et al., 2008b). Examples of results and images from these studies are shown in figure X.
Richardson, S. Water Analysis: Emerging Containments and Current Issues. Journal of Analytical Chemistry. 2003, 75, 2831-2857.
GO is verified to be a nano-material with amphiphilic nature, as the water molecules are adsorbed initially at the hydrophilic terminal (hydroxides), then quickly diffused among the hydrophobic carbon core, developing a water channel that improve permeation flux. Once water molecules infiltrate over the GO layers, they built up to arise a single layer configuration that drives the consecutive layers apart from each other, resulting in the increase of the d-spacing (Hung et al., 2014). The unique properties of GO-based water desalination membrane could open the door of opportunities to overcome the challenges, in order to make clean water easily reached around the earth.
Development of specific ethers has been inactive and fruitful area of investigation in the past few decades.2The strategy of ether catalysis General encompasses synergistic activation of a ethers an electrophile by two or more reactive centers through the combination of a Lewis acid and Lewis base working in concert. Such approach results in high reaction rates and excellent ethers. Hydrogen bonding plays a crucial role in this catalysis. Hydrogen bonding to an electrophile decreases the electron density of this species, activating it toward nucleophilic attack. Recently chemists have begun to appreciate the tremendous potential offered by hydrogen bonding as a tool for electrophile activation in synthetic catalytic systems. In particular, ethers donors have emerged as a broadly applicable class of catalysts for ethers synthesis. An amide unit, the key functional group of peptides, plays an important role in catalyst design and modification. Based on the understanding of different asymmetric catalytic reaction mechanisms, the creation of amide structure-based ether and was realized by rational arrangement of hydrogen-bond networks. According to their model, two water molecules simultaneously establish H-bonds to the carbonyl oxygen of the substrate for optimal transition state stabilization. The concept of explicit double H-bonding activation was no longer restricted to one type of reaction or catalyst, but became a generally applicable principle. The simultaneous donation of two hydrogen bonds has proven to be a highly successful strategy for electrophile activation. Such interactions benefit from increased strength and directionality compared to a single hydrogen bond. Ethers containing double hydrogen bond ethers are capable of directing the assembly of molecules with similar control as