Dimethyl physical properties

Standard polyester fibers contain no reactive dye sites. PET fibers are typically dyed by diffusiag dispersed dyestuffs iato the amorphous regions ia the fibers. Copolyesters from a variety of copolymeri2able glycol or diacid comonomers open the fiber stmcture to achieve deep dyeabiHty (7,28—30). This approach is useful when the attendant effects on the copolyester thermal or physical properties are not of concern (31,32). The addition of anionic sites to polyester usiag sodium dimethyl 5-sulfoisophthalate [3965-55-7] has been practiced to make fibers receptive to cationic dyes (33). Yams and fabrics made from mixtures of disperse and cationicaHy dyeable PET show a visual range from subde heather tones to striking contrasts (see Dyes, application and evaluation). 

Uses. The chemical inertness, thermal stability, low toxicity, and nonflammability of PFCs coupled with their unusual physical properties suggest many useflil applications. However, the high cost of raw materials and manufacture has limited commercial production to a few, small-volume products. Carbon tetrafluoride and hexafluoroethane are used for plasma, ion-beam, or sputter etching of semiconductor devices (17) (see loN implantation). Hexafluoroethane and octafluoropropane have some applications as dielectric gases, and perfluorocyclobutane is used in minor amounts as a dielectric fluid. Perfluoro-1,3-dimethyl cyclohexane is used as an inert, immersion coolant for electronic equipment, and perfluoro-2-methyldecatin is used for... 

Diisobutyl Ketone. Diisobutyl ketone (DIBK) (2,6-dimethyl-4-heptanone) is a colorless stable Hquid with a peppermint odor. Some physical properties are Hsted in Table 1. 

Physical Properties. Industrially, the most important esters are dimethyl malonate [108-59-8] and diethyl malonate [105-53-3] whose physical properties are summarized in Table 2. Both are sparingly soluble in water (1 g/50 mL for the diethyl ester) and miscible in all proportions with ether and alcohol. 

Table 2. Physical Properties of Dimethyl and Diethyl Malonate...

ROOC—COOH, are not. The dialkyl esters are characterized by good solvent properties and serve as starting materials in the synthesis of many organic compounds, such as pharmaceuticals, agrochemicals, and fine chemicals (qv). Among the diesters, dimethyl, diethyl, and di- -butyl oxalates are industrially important. Their physical properties are given in Table 7. 

The physical properties of finish removers vary considerably due to the diverse uses and requirements of the removers. Finish removers can be grouped by the principal ingredient of the formula, method of appHcation, method of removal, chemical base, viscosity, or hazardous classification. Except for method of apphcation, a paint remover formulation usually has one aspect of each group, by which it can be used for one or more appHcations. A Hst of the most common organic solvents used in finish removers has been compiled (3). Many are mentioned throughout this article others include ethyl lactate [97-64-3] propylene carbonate [108-32-7] furfural alcohol [98-01-1/, dimethyl formamide [68-12-2] tetrahydrofuran [109-99-9] methyl amyl ketone [110-43-0] dipropylene glycol methyl ether [34590-94-8] and Exxate 600, a trade name of Exxon Chemicals. 

The physical properties of the acids, the most important anhydrides, and the full methyl esters are summarized ia Tables 2, 3, and4. Detailed Hsts of physical properties for phthaUc acid and its anhydride, terephthaUc acid and dimethyl terephthalate, isophthaUc acid, trimeUitic acid and its anhydride, and pyromeUitic acid and its dianhydride/ are provided under the sections describiag these compounds. 

Derivatives. In general, the esters of terephthaHc acid derived from saturated alcohols undergo the same reactions as dimethyl terephthalate. Some physical properties of six of these esters are Hsted in Table 23. The di- -butyl and di-2-ethyIhexyl esters find use as plasticizers (qv). Terephthaloyl chloride, which is prepared by reaction of terephthaHc acid and thionyl chloride, is used to prepare derivatives of terephthaHc acid. 

Table 22.4 Influence of amount of plasticiser (dimethyl phthalate) on some physical properties of cellulose acetate compositions...

Poly(2,6-dimethyl-l,4-oxyphenylene) (poly(phenylene oxide), PPG) is a material widely used as high-performance engineering plastics, thanks to its excellent chemical and physical properties, e.g., a high 7 (ca. 210°C) and mechanically tough property. PPO was first prepared from 2,6-dimethylphenol monomer using a copper/amine catalyst system. 2,6-Dimethylphenol was also polymerized via HRP catalysis to give a polymer exclusively consisting of 1,4-oxyphenylene unit, while small amounts of Mannich-base and 3,5,3, 5 -tetramethyl-4,4 -diphenoquinone units are always contained in the chemically prepared PPO. 

The physical properties of the anhydrate form and two polymorphic monohydrates of niclosamide have been reported [61], The anhydrate form exhibited the highest solubility in water and the fastest intrinsic dissolution rate, while the two monohydrates exhibited significantly lower aqueous solubilities. In a subsequent study, the 1 1 solvates of niclosamide with methanol, diethyl ether, dimethyl sulfoxide, N,/V -dimethyl formamide, and tetrahydrofuran, and the 2 1 solvate with tetraethylene glycol, were studied [62], The relative stability of the different solvatomorphs was established using desolvation activation energies, solution calorimetry, and aqueous solubilities. It was found that although the nonaqueous solvates exhibited higher solubilities and dissolution rates, they were unstable in aqueous media and rapidly transformed to one of the monohydrates. 

Secalin. Secalin has been isolated from the stems of unripe rye.46,68 Schlubach and Bandmann69 studied its structure. The great difficulty they encountered in obtaining the polysaccharide and its acetate in homogeneous form made the determination of physical properties uncertain. However, by hydrolysis of the methyl derivative, they obtained, after separation by means of the /3-naphthoates, tetramethyl-, trimethyl-, and dimethyl-D-fructoses in the proportions of 1 2 1. The trimethyl-D-fructose was identified as 1,3,4-trimethyl-D-fructofura-nose by its melting point and specific rotation. 

Dimethyl-l-propanol butyraldehyde derivative, 4 461 physical properties of, 2 764t... 

Dimethylacetamide (DMAc), cellulose solvent (with lithium chloride), 5 384 N, N-Dimethylacetamide (DMAc), 23 703 extractive distillation solvent, 8 802 solvent for cotton, 8 21 N, AA-Dimethylacrylamide (DMA), 20 487 P,P-Dimethyl acrylic acid, physical properties, 5 35t Dimethylallylamine, 2 247... 

Dimethylarsinic acid (DMA), 3 274 present in water and food, 3 276t Dimethylbenzyl carbinol, aroma chemical derived from toluene, 3 234 N, AT-Dimethylbenzyl vinyl amine (DMBVA), 20 487 Dimethylbismuthine, 4 18, 26 Dimethylbromostibine, 3 68 Dimethylcadmium, 4 516-517 physical properties of, 4 517t Dimethyl carbonate, 6 313-314... 

Methyl-2-butenoic (P,P-dimethyl acrylic) acid, physical properties, 5 35t... 

The Physical Properties of 2,S-Dimethyl-x>-glucose and Some of Its Derivatives... 

Know the physical properties of the substances with which you are working. Keep in mind that some compounds (such as acetaldehyde and tritiated water) have low boiling points. Again, keep in mind that some gloves do not offer an adequate barrier to certain chemicals. Some compounds enter the body with such facility that special care must be exercised when they are in use. One example is dimethyl sulfoxide, which as a solvent facilitates the entry of many solutes into the body. There are many known cases where radiolabeled compounds contaminated individuals who failed to consider this power of DMSO as a solute vehicle. 

Initially choline, (CH3)3N+CH2CH20H = trimethyl-2-hydroxyethylamminium, was introduced for tumor imaging labeled with [ C] by Hara et al. [175,176]. However, the short half-life of [ C] (20 min) limits its use in institutions with a cyclotron on site. This led to the development of [ F] (half-life 110 min) labeled choline taking also advantage of the better physical properties for imaging of F compared with [ C] [178]. Two compounds of p F]-labeled choline analoga are currently in use 2-[ F]-fluoroethyl-dimethyl-2-hydroxyethyl-ammo-nium ([ F]-FEC) and [ F]-fluoromethyl-dimethyl-2-hydroxyethylammonium choline (p F]-FCH) [178,179]. 

---