Solvent conventional

In the following, we write the protic solvents conventionally as SH, where H is the proton and S is the solvent residue. They include many compounds with -OH and >NH groups, also some others (Table 8.1). All these solvents are polar, have... 

ISO 6427 (1992) describes the determination of matter extractable from plastics by organic solvents (conventional methods). Solvent extraction has been reviewed [59]. Few books are dedicated to the multifarious extraction methods in organic analysis [60]. 

Figure 9.5 Sammon map representing similarity of extraction ability of solvents (with respect to extraction of neutral organic compounds). The closer the points are on the map, the more similar are the corresponding solvents. Conventional solvents are designated by numbers, some representative numbers are m-xylene—35, butyl acetate—9, 1-octanol—40. The point marked BMImPF, represents l-butyl-3-methyl-imidazolium hexafluorophosphate ([C4CiIm][PF5]).

This review article deals with aromatic polyimides that are processable from the melt or soluble in organic solvents. Conventional aromatic polyimides represent the most important family of heat resistant polymers, but they cannot be processed in the melt, and their application in the state of soluble intermediates always involves a hazardous step of cyclodehydration and elimination of a non-volatile polar solvent. A major effort has therefore been devoted to the development of novel soluble and/or melt-processable aromatic polyimides that can be applied in the state of full imidation. The structural factors conducive to better solubility and tractability are discussed, and representative examples of monomers showing favourable structural elements have been gathered and listed with the chemical criteria. Experimental and commercial aromatic polyimides are studied and evaluated by their solubility, transition temperatures and thermal resistance. An example is also given of the methods of computational chemistry applied to the study and design of polyimides with improved processability. 

Convention I (Raoult s Law, Solvent Convention, or Rational Convention ) In this case, the standard state is taken as the pure substance (x- = x] = 1), so that, by (7.85), we are choosing y- = 1 [so that /a 1 = /a, suggesting the filled-circle notation in (7.78)]. Thus, we can state this convention as... 

A wide range of dilferent reactor types e.g. continuous, membrane, bubble) have been used to perform large scale processes using alternative solvents. Conventional batch reactors and extraction vessels have been used in many cases. However, process intensification is moving forward hand in hand with alternative solvents and therefore engineering solutions often have an important role to play in this field. Nevertheless, these are not discussed at length in this chapter and will probably be the subject of another book within the green chemistry series. 

Liquid NMR requires the use of deuterated solvents. Conventionally, the sample is analyzed as a solution using a 5- or 3-mm NMR tube, depending on the NMR probe, which requires ca. 500 or 150 pL, respectively, of deuterated solvents. The increased solvent requirement for LC-NMR makes this technique highly expensive. 

An alternative approach to the use of high-temperature solvents, which can be both toxic and expensive, is to use more usual solvents conventionally limited by their rather low boiling points. However, solvents can be used well-above their boiling point at atmospheric pressure if heated in a sealed vessel (an autoclave or bomb ) the autogenous pressure then far exceeds the ambient pressure raising the boiling point of the solvent. Such solvothermal reaction conditions are extensively used in the preparation of inorganic solids, especially zeolites [64]. Eor a comprehensive review of this method for nanopartides see [65]. 

Solvent Conventional boiling point (°G) Operating temperature in the microwave cavity (°C) Pressure (bar)... 

Any organic solvent Conventional organic solvents Any solvent Chloral monomer... 

So, to be definitive, for uncharged molecules we choose one of two standard conventions. The solvent convention is used when the exchangeable component B is the majority component. Then ideality (yb(xb) 1) is defined in the limit as B becomes pure solvent, xg 1. In this case, p° (liquid) is the chemical potential for a B molecule completely surrounded by other B molecules. 

Suppose you are interested in the case in which the exchangeable component is the solvent. Use the solvent convention, = 1 for = 1. The vapor pressure over pure B gives you the quantity pl = QxplApykT], so Equation (16.8) becomes... 

Solvent Convention. To find the correspondence between the lattice and thermodynamic models in the solvent convention, let yb(xb) 1 as Xb 1 to reduce Equation (16.10) to... 

We are interested in how liquid and gas chemical potentials depend on xb and r, at fixed pressure p. For the liquid solution, we have peiliquid, T, xg) = Pg (liquid, T) + fcTlnygXg, where the superscript ° for the liquid state in the solvent convention means that the liquid B is pure and contains no solute. 

In that excess Gibbs energy, there is no contribution from the solvent. We can deduce fi om this that = 1 - Therefore, as is the case for the solvent, conventions (I) and (II) are identical, so we can deduce ... 

ISO 6427 [483] Plastics determination of matter extractable by organic solvents (conventional methods)... 

Convention II is sometimes referred to as the application of the solute standard state to the solutes and the application of the solvent standard state to the solvent. Convention I is called the application of the solvent standard state to every component. The reason for having two conventions is that we would like to have activity coefficients nearly equal to unity as often as possible. In convention I we describe the deviation of each substance from Raoult s law. If Raoult s law is approximately obeyed by all substances, the use of convention I gives an activity coefficient approximately equal to unity for each substance. In convention II we describe the deviation of the solvent from Raoult s law and the deviation of a solute from Henry s law. If Henry s law is approximately obeyed by a solute, the use of convention II gives an activity coefficient approximately equal to unity for that solute, as well as an activity coefficient approximately equal to unity for the solvent, which would approximately obey Raoult s law. 

Another major problem in development of HPLC-NMR involved the use of deuterated solvents. Conventional high-resolution NMR spectroscopy routinely uses deuterated solvents. However, these solvents are thought to be prohibitively expensive if they have to be used for elution in HPLC-NMR... 

Extraction procedure is the key step in the separation of medicinally active constituents from the plant or animal tissues using different solvents. Conventionally, the medicinal plants were consumed in the form of decoction prepared by using either water or water-alcohol mixture. Over the years, several novel extraction procedures have been developed including infusions [45]. 

Two of the major disadvantages of PPO as a gas separation membrane material are its comparatively lower selectivity to gases and its insolubility in dipolar aprotic solvents conventionally used in the membrane fabrication process. It has also been mentioned by Zampini that PPO has a low resistance to most common organic solvents. Aromatic and chlorinated hydrocarbons dissolve PPO, while other solvents and solvent vapors induce crazing in the molded PPO under stress thus causing almost complete loss of strength. 

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