Action of Solvents

Single base propellants are basically nitrocellulose which has been made colloidal by the action of solvent. 

A similar reaction is the methylenation of 3,4-dihydroxybenzaldehyde in the presence of a phase-transfer catalyst on a benign calcium carbonate surface [26]. Presumably, bonding of the vicinal hydroxyl groups is low thereby enhancing the reaction with the alkylating agent under the action of solvent-free microwave irradiation (Eq. 15). 

Elastomers produced by copolymerisation of a nitroso monomer with tetrafluoroethylene they have excellent resistance to heat, to the action of solvents and to chemical attack, and are completely non-flammable. 

Our understanding of lyotropic liquid crystals follows in a similar manner. The action of solvent on a crystalline substance disrupts the lattice structure and most compounds pass into solution. However, some compounds yield liquid crystal solutions that possess long-range ordering intermediate between solutions and crystal. The lyotropic liquid crystal can pass into the solution state by the addition of more solvent and/or heating to a higher temperature. Thermotropic and lyotropic liquid crystals, both turbid in appearance, become clear when they pass itno the liquid and solution states, respectively. 

The crystallization tendency of polycarbonate is enhanced by the action of solvents. For example, crystallization may be accomplished by slow evaporation of solvent from cast film (14, 17) or by treatment with swelling agents such as ethyl acetate or acetone. 

Unpublished microscopic experiments of T. Urbanski [29] on the dissolution of nitrocellulose fibres provide additional evidence that there exists a layer hindering the action of solvents, since the fibre starts to dissolve at the ends which have been tom and frayed by passage through the beaters. 

See also Cellulose Nitrate, Action of Solvents, Vol 2, pCllS-R... 

Nondestructive solvent extraction of coal is the extraction of soluble constituents from coal under conditions where thermal decomposition does not occur. On the other hand, solvolysis (destructive solvent extraction) refers to the action of solvents on coal at temperatures at which the coal substance decomposes and in practice relates in particular to extraction at temperatures between 300 and 400°C (572 and 752°F). In the present context (i.e., the solvents extraction of coal), the solvent power of the extracting liquid appears to be determined solely by the ability of the solvent to alter the coal physically (by swelling). In this respect, the most effective solvents are aromatics, phenol derivatives, naphthol derivatives, anthracene, and phenanthrene. 

In the case ofintermolecular e.t. it is generally supposed that the electron jump is quasi instantaneous, so that no such cooperative action of solvent relaxation can take place. However, if a local polarity fluctuation is required for e.t., then the occurrence of such fluctuations can still be controlled by the motion of the solvent. From many experimental data, solvent motion appears to become the rate limiting factor when alcohols are used as polar liquids. Table 3 lists a selection of such data, with those obtained in acetonitrile for comparison [75]. 

DISCESSUS — Discession, or Separation, is performed when the essential potencies of a substance are separated and disjoined by the action of solvent heat. This is done by exhalation and resolution of composites. Separation by the first process occurs when a component part is so attenuated that it passes into a spirit. And that is chiefly termed exhalation when a substance is liberated and set free into the air. When it is intercepted, the process is called Distillation, or Sublimination which operations serve sometimes in place of exhalation. There is exspiration, i.e., exhalation, from things moist and from things which steam. 

The polyether or polyester blocks provide the necessary rubberiness, whereas the accumulation of relatively stiff links with hydrogen bonding capacity between the elastomeric blocks increases resistance to high temperatures and the action of solvents. It also increases the modulus of elasticity and the ultimate tensile strength of the resulting fibers. 

T. Urbanski and D browska [33a] examined infra-red spectra of mono-, di-, and trinitrophenols and particularly [33b] the action of solvents on hydrogen bonding between o-nitro and the phenolic group. They found that polar solvents can break a hydrogen bond. This is discussed in the paragraphs on hydrogen bonds and in the description of dinitro and trinitro phenols. 

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