Preparative tricks

Several preparative tricks have been developed to increase the rate of inorganic reactions. They are based on ... 

Although Fields already mentioned the possible preparation of monolithic silica-based CEC columns, the lack of experimental data leads to the assumption that this option has not been tested [111]. In fact, it was Tanaka et al. who demonstrated the preparation of monolithic capillary columns using a sol-gel transition within an open capillary tube [99,112]. The trick was in the starting mixture that in addition to tetramethoxysilane and acetic acid also includes poly(ethylene oxide). The gel formed at room temperature was carefully washed with a variety of solvents and heated to 330 °C. The surface was then modified with octadecyl-trichlorosilane or octadecyldimethyl-A N-dimethylaminosilane to attach the hy-... 

The primary object of this book is to provide the HPLC practitioner with a handy guide to the use of HPLC for analyzing pharmaceutical compounds of interest. This means familiarizing the practitioner with the theory, instrumentation, regulations, and numerous applications of HPLC. This handbook provides practical guidelines using case studies on sample preparation, column or instrument selection, and summaries of best practices in method development and validation, as well as tricks... 

This chapter provides the novice and the experienced analyst with an overview of sample preparation techniques focusing on solid dosage forms. It describes the best practices in the dilute and shoot approach, and the tricks of the trade in grinding, mixing, sonication, dilution and filtration of drug products. Selected case studies of sample preparations for assays and impurity testing are used to illustrate the strategies, trade-offs... 

This could be your lucky day. You can make new discoveries, create a tasty treat, or devise a new magic trick. But you have to be prepared. You have to have the right materials, the right setup, and, most of all, the right attitude. With these three things you ll learn as much as you can, as safely as you can, and with as much fun as possible. 

Most traditional methods use hydrochloric acid solutions as the acid reagent for the hydrolysis or alcoholysis of fi-lactams. Methanolic solutions of trimethylchloro-silane are able to generate HCI in situ, and the trick has been employed successfully for the methanolysis of fi-lactams in a route to aspartic acid derivatives [60, 61] and 2-oxazolidinones[62], respectively. Recently the use of silica-supported acid reagent has been reported as a convenient alternative. The reagent (Si02-Cl) prepared from admixing silica gel and SOCl2 in dichloromethane and subjected to dryness, is able to run the methanolysis of (1-lactams at room temperature in 20 min [63]. 

According to literature sources mainly oxides, nitrides, borides and carbides are used as ceramic raw materials of chemical and structural applications and the most common elements in these compounds are Be, Mg, Ca, Ti, V, Cr, Y, Zr, La, Hf, W, B, Al, Si and Sn. These elements can be found in rather small area of the periodic table, i.e. in the groups 2 up to and including 6, 13 and 14. So apparently relatively few ingredients are used in this branch of ceramics to produce a wide range of products. The tricks of the trade are in the preparation. The properties are determined by a number of factors, such as the nature of the building blocks, the kind of bonds, the strength of the bonds, the crystal structure and the reactivity of the material. 

One of the more useful synthetic tricks developed for the preparation of proces-sible conjugated polymers has been the incorporation of ionic pendant groups that can induce water solubility. As polymer chemists look to prepare materials that are more environmentally benign, these water-soluble polymers may ultimately prove to be of commercial importance. 

Using polar chains and polar arrays to bias the formation of acentric bulk materials is a promising and potentially useful approach to designing acentric solids, but is somewhat unsatisfying because the nature of the bias is not well understood and is thus not easy to control. In searching for a more definitive and logical mechanism for preparing acentric bulk materials, we have borrowed one of nature s tricks. 

This scene is a very important plot sequence. It introduces us to the character of Celia, prepares for Corvino s betrayal of an Italian s honor, and sets the scene for Volpone s greatest trick. The reader must remember that the action started in the fox s lair, moved into the open of the streets of Venice, and is now located in the bird s nest. 

A matrix adapted for <10 kDa peptides such as a-cyano-4-hydroxycinnamic acid and the adapted solvents (4HCCA, 40 mg/mL in acetone) for preparing the different solutions for sample preparation acetone, TFA, acetonitrile, and water (all HPLC grade). To select the best methodologies for sample preparation, some tricks are discussed in (26). 

We have recently used a stereochemical trick to solve this pending structural problem. The anellation of the chiral (.v-/ruH.v-r 4-C4H6)IV1 subunit with a chiral bent metallocene leads to the formation of a pair of diastereomeric (s-/nmv- b u tad i e n e) m e t a 11 oce ne complexes. Crystals of a single diastereomer were obtained that were free from the otherwise so often observed disorder phenomena. The actual example was prepared by... 

The process for preparing macrolactones described in the text is impractical. Instead of this process one uses a continuous method with a syringe pump a solution of the hydroxycar-boxylic acid is added very slowly—that is, in the course of hours or days—i nto a small flask, which contains > 1 equivalent of the activator and, if necessary, just enough triethylamine to neutralize any released HC1. The rate at which the acid is added is regulated such that it is equal to or smaller than the lactonization rate. This is called pseudo high dilution. At the end of the reaction the lactone solution can be relatively concentrated, e. g., 10 mmoEL, at least 10,000 times more concentrated than without the use of this trick. 

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