Chemicals continued xylene

Solvent Resistance. At temperatures below the melting of the crystallites, the parylenes resist all attempts to dissolve them. Although the solvents permeate the continuous amorphous phase, they are virtually excluded from the crystalline domains. Consequently, when a parylene film is exposed to a solvent a slight swelling is observed as the solvent invades the amorphous phase. In the thin films commonly encountered, equilibrium is reached fairly quickly, within minutes to hours. The change in thickness is conveniently and precisely measured by an interference technique. As indicated in Table 6, the best solvents, specifically those chemically most like the polymer (eg, aromatics such as xylene), cause a swelling of no more than 3%. 

In continuation of the work on oxidation reactions, Ambulgekar et al. [31] investigated different chemical reactions (oxidation of toluene, (o-/p-/w)-xylenes,... 

Water/hydrocarbon mixture Condensation, separation of the liquid water/ben-zine. The waste gas is ignited and the wastewater is fed to a treatment plant, e) Recovery of methanol and toluene [115]. During the production of a textile chemical a solution (mother liquor) is produced containing methanol and an aromatic solvent (toluene or xylene). An azeotrope containing methanol and toluene is produced by discontinuous ditillation. The toluene-containing phase separates out on addition of water. Methanol is recovered from the methanol-containing phase by continuous... 

A chemical process uses physical and/or chemical operations to transform feed materials into products of different composition. Table 9,1 lists the types of operations that are most widely used. Depending on the production rate and the operations used, the process is conducted batchwise, continuously, or cyclically. A continuous, heat-integrated process that illustrates several of the operations in Table 91 is shown in Figure 91. where benzene and a mixture of xylene isomers are produced by the disproportionation of toluene. The heart of the process is a fixed-bed catalytic reactor, R-1, where the main chemical change is the reaction... 

In addition to the variety of isomerization and rearrangement reactions leading to an abundance of different flavor and fragrance chemicals, a- and P-pinene also undergo carbocationic polymerization to yield polyterpene resins (Figure 3B.10).The reaction can be conducted as a batch or continuous polymerization of P-pinene and a smaller fraction of the less reactive a-pinene in a solvent such as xylene and is catalyzed by Lewis acid metal halides, such as aluminum trichloride (AICI3) in the presence of some parts per million of water to create a strong proton donor (the vast majority of pinene polymerization involves with the use of P-pinene, not a-pinene, mostly due to intrinsic... 

Badjagbo K, Picard P, Moore S, et al. Direct atmospheric pressure chemical ionization-tandem mass spectrometry for the continuous real-time trace analysis of benzene, toluene, ethylbenzene and xylenes in ambient air. J Am Soc Mass Spectrom. 2009 20 829-36. 

Having set the basis for future catalyst improvements by unraveling the complex reaction networks of the reaction of o-xylene to phthalic anhydride, Clariant will continue to broaden this knowledge based on a profound physico-chemical understanding of the processes at the catalyst surface during its life cycle. This enables Clariant to further improve and widen the applicability of this family of PHTHALIMAX catalysts. 

There are two major chemical processes used for manufacturing alkyds the fusion process and the azeotrope process (solvent process). The fusion process is an old method of manufacturing alkyd that involves fusing all components at elevated temperature. An inert gas is continuously purged in the system to avoid oxidation as well as to drive off water of the reaction. Alkyds made by this process are often darker in color. Due to the possibilities of sublimation of phthalic anhydride and loss of polyols, this process suffers from poor reproducibility. In the solvent process, poly condensation is carried out in the presence of a small quantity (5 to 10 % of reaction mass) of hydrocarbon solvents (normally xylene or toluene) in... 

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