Substrate Preparation Methods

Thin oxide films may be prepared by substrate oxidation or by vapour deposition onto a suitable substrate. An example of the fomrer method is the preparation of silicon oxide thin-films by oxidation of a silicon wafer. In general, however, the thickness and stoichiometry of a film prepared by this method are difficult to control. 

A few miscellaneous spiro heterocyclic compounds have been shown to act as substrates for the primary synthesis of regular quinoxalines. However, none of the following recent examples appears to have much potential as a preparative method. 

XANES, which can be used to determine molecular structure and orientation of chemisorbed molecules on well-characterised single-crystal surfaces and is able to discriminate between the same atoms in different bonding situations, has been used to examine the supramolec-ular organisation adopted by the dye Reactive Red 3 1 physisorbed and chemisorbed on to cotton and cellophane substrate materials [315]. A distinct difference in the nature of the dye/cotton interaction was observed for different preparative methods. The mode by which... 

Direct formation of fj-FeSiy A preparation method for 3-FeSi2 was proposed by Oikawa and Ozaki (2002) to activate the interfacial reaction between Fe and Si powders through a heat process in a sealed ampoule. The mechanism of the reaction process was investigated by using sputtered Fe films on Si substrate (and on sapphire substrates). It was found that Si vapour reacts, in sealed ampoules, with solid Fe, and it is saturated to form e-FeSi. Reaction of FeSi with solid Si then takes place to form FeSi2. It was suggested that this process has a potential interest in the activation of reactions with Si of other refractory metals. 

In search of a convenient procedure for preparing diazo substrates for the cycloaddition to Cgg, Wudl introduced the base-induced decomposition of tosyl-hydrazones [116]. This procedure allows the in situ generation of the diazo compoimd without the requirement of its purification prior to addition to Cgg. Since they are rapidly trapped by the fullerene, even unstable diazo compounds can be successfully used in the 1,3-dipolar cycloaddition. In a one-pot reaction the tosyUiydrazone is converted into its anion with bases such as sodium methoxide or butylHfhium, which after decomposition readily adds to Cgg (at about 70 °C). This method was first proven to be successful with substrate 142. Some more reactions that indicate the versatility of this procedure are shown in Table 4.4. Reaction of 142 with CgQ under the previously described conditions and subsequent deprotection of the tert-butyl ester leads to [6,6]-phenyl-C5j-butyric acid (PCBA) that can easily be functionalized by esterification or amide-formation [116]. PCBA was used to obtain the already described binaphthyl-dimer (obtained from 149 by twofold addition) in a DCC-coupling reaction [122]. 

The preparation method is similar to that for the cresol-formaldehyde Novolak resin with a molar ratio of cresol/benzaldehyde = 1.1 in acidic conditions. We have prepared varieties of substituted m-cresol-benzaldehyde Novolak resins, and 1-, and 2-naphthol-4-hydroxybenzaldehyde Novolak resins in the same manner. Almost all of these benzaldehyde Novolak resins give excellent resist films when spin-coated onto silicon or silicon dioxide substrates after being dissolved, together with a photoactive compound, in a solvent like 2-... 

The very great majority of systematic preparative methods for metal diketonates employs the neutral /3-diketone as a starting material. This may be reacted with various types of substrates, e.g. 

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