Volatile byproducts

Me3Si0C(0)NMe2. This reagent produces volatile byproducts and autocatalytically silylates alcohols, phenols, and carboxylic acids. 

Vessels designed for microwave-assisted SPOS must fulfill several require-menfs because of fhe harsh conditions (i.e., high temperatures and pressures) usually associated with microwave heating. Open vessels are often impractical because of the possible loss of solvent and/or volatile reagents during the heating process. However, in cases where a volatile byproduct inhibits a reaction, their use may be superior over closed systems. A sealed vessel retains the solvents and reagents, but must be sturdily constructed to avoid the obvious safety implications due to the buildup of pressure. 

Because the condensation between a diketene acetal and a diol proceeds without the evolution of volatile byproducts, this method allows the preparation of dense, crossUnked materials by using reagents having a functionality greater than 2 (15). Even though either or both the ketene acetal and alcohol could have functionalities greater than 2, only triols were investigated because the synthesis of trifunctional ketene acetals is extremely difficult. 

Evaporation of volatile byproducts and solvents is often used to obtain the solid metal nanoparticles. The residue may contain metal nanoparticles and protective reagents. When the nanoparticles are well protected by ligands or polymers, then the solid residues can be dispersed again without coagulation of the particles. When the nanoparticles are not well protected, however, the evaporation often results in aggregation of the nano-particles. 

BSTFA Produces volatile byproducts which do not interfere with the GC analysis of low molecular weight compounds. Reactivity is similar to BSA and is generally preferred to BSA for most applications. 

Ester interchange and transesterification reactions are thermochemically neutral reactions which may be driven in the desired direction through the use of excess diol and by removal of volatile byproducts from the system. 

PTT has different side reaction products. Instead of the acetaldehyde produced with PET, acrolein and allyl alcohol are the volatile byproducts of PTT production. The generation of acrolein is to be expected since it is one of the starting raw materials for making PDO. Acrolein is toxic and is a very strong lachrymator [22], and requires special handling and treatment. 

Caution. CO gas and phosgene (which may be formed as a volatile byproduct in the first step) are highly toxic. Appropriate personal protection must be adopted and all manipulations must be carried out in a highly efficient fume hood. 

Deposition of ruthenium thin films has been achieved using this CVD source reagent. For the experiments conducted under H2, a large amount of the free ligand (hfac)H is obtained as a volatile byproduct, suggesting that the deposition of mthenium is proceeding by the following pathway ... 

For the deposition reactions carried out under an Ar atmosphere, up to 41% of the dark red tris-/3-diketonate complex Ru(hfac)3 is observed as a volatile byproduct. This finding suggests that the operation of a parallel pathway, which involves self-disproportionation of the source reagent, is necessary to account for the observed film growth ... 

Although several high modulus materials have been identified in this chapter as well as current commercial materials, a more wide spread acceptance of these materials will occur if their compressive properties are vastly improved. We have discussed several synthetic approaches to improve the compressive properties by structural changes of PBZX systems with small increments of improvement. From what has currently been done, crosslinking seems to have shown the greatest improvement. An in-depth study on a rigid-rod polymer system that forms three dimensional crosslinks by an addition mechanism without the evolution of volatile byproducts is required. For the most part, innovative approaches, both chemical and physical, are required to attack and solve this deficiency. 

The charged autoclaves are heated, preferably in a rocking muffle furnace. After heating for the required period, the autoclave is allowed to cool to ambient temperature, and excess sulfur tetrafluoride, thionyl fluoride and other volatile byproducts are vented from the autoclave and absorbed in an alkaline absorbent. If the gaseous products are of interest they are condensed... 

Ionic liquids based on salts of alkylimida-zoles and pyridines have been used for the synthesis of esters of ascorbic acid and other sugars on the laboratory scale and show particular advantage in their ability to dissolve otherwise incompatible substrates. One of the key features of these solvents is their extremely low vapor pressures and excellent ability to dissolve both polar and nonpolar materials. Reactions can be run under vacuum allowing the removal of volatile byproducts such as water and enable one to... 

In the previous examples, disubstituted double bonds have been synthesized via ring-closing metathesis. As shown in Scheme 5, it is possible to extend the method to tri- or tetrasubstituted double bonds. Thus, bisallylic ether 33 leads to the trisubstituted olefin 34 and compound 35 gives the tetrasubstituted olefin 36 [3]. Here, the additional substituents are simple methyl groups, but silyl groups for example, can be introduced too. The volatile byproducts in these cases are not ethylene but butene or propene. 

Another selective approach to the synthesis of heterobimetallic compounds is the reaction of bivalent tin with a commercially available hydroxide or acetate, with the elimination of a small molecule, such as alcohol, or a volatile byproduct, such as CO. ... 

Experimental details are outlined in Refs. 4 and 5, so only the essential features of the experiments are reproduced here. Fe(C0)5 was obtained from Strem and was separated from non-volatile byproducts by a bulb-to-bulb distillation. The purified Fe(CO)s was stored at liquid nitrogen temperature in a Pyrex bulb sealed with a greaseless stopcock, except when in use. The bulb was degassed before each use. Fe3(CO)i2 and Fe2(C0)g were also obtained from Strem and were used without purification. 

The fluid dimer polyamides and fatty amido amines also react with phenolic resins (23). These reactions are significantly different from those of epoxy resins. With the heat-reactive phenolic resins, the aminopolyamide portions react with methylol groups. A carbon-nitrogen bond or cross-link is formed and a volatile byproduct, water, is produced. This reaction requires external heat to remove water. At temperatures near 150 °C the reaction proceeds smoothly. Since curing at elevated temperatures is required, the pot life or shelf life at room temperature is relatively long. The liquid dimer polyamide and fatty amido amines also react with alpha, beta unsaturated acids and esters (29) and with polyesters (30). The unsaturated esters reduce viscosity, lengthen useful pot life, and reduce heat of reaction. Thus, they are useful diluents when low viscosity is desired. 

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