Solvents

J.A. Bonventre , in Encyclopedia of Toxicology (3rd Edition), 2014

Background

Solvents are a heterogeneous group of structurally diverse chemicals that tin be used to dilute, dissolve, or disperse other compounds. The power of a solvent to deliquesce another molecule is dependent on molecular structure and physical backdrop of both the solvent and the solute. Solvents tin be categorized as organic or inorganic, and in terms of chemic polarity. Polar solvents include water, alcohols, and other –OH containing chemicals, such as acetic acid, that have the power to donate a H + and class hydrogen bonds. Polar solvents lacking an –OH group, including acetonitrile, dimethylformamide, and dimethylsulfoxide are protophilic solvents, and are used to dissolve less polar solutes. Nonpolar solvents are not miscible in water and are therefore used to dissolve hydrophobic substances such every bit oils and fats. This category of solvents includes benzene, carbon tetrachloride, diethyl ether, hexane, and toluene. Use of inorganic nonaqueous solvents is less common and mostly employed under controlled laboratory environments. Such solvents, including liquid ammonia, phosphoryl chloride, and sulfuric acid, may be desirable in chemical reactions in which the reactants would have the potential to interact with a polar solvent. Many solvents are likewise categorized equally volatile organic compounds (VOCs), and a discussion of further sub-classing can be found in the VOC entry. Similarly, Stoddard Solvents/White Spirits refers to a specific mix of aliphatic and alicyclic hydrocarbons distilled from crude oil.

Toxicity of solvents can vary widely. Water, considered the universal solvent, demonstrates very low toxicity, while in contrast, benzene, once widely used in industrial and household products, has been largely replaced due to its known human carcinogenicity. The diversity inside this grouping of chemicals allows for broad usage beyond multiple industrial practices besides as at domicile. Occupational or ecology exposures to solvents occur every bit a consequence of the commonplace utilize of many solvents and the relative ease with which they are captivated.

In recent years, at that place has been a motion to replace many of the more toxic solvents with less toxic alternatives. Alcohols and alkanes, for instance, were shown to be less harmful to the surroundings than acetonitrile, dioxane, and tetrahydrofuran. In addition, the green chemistry move also challenged chemists to find nontoxic and sustainable replacements. Limonene, isolated from the rind of citrus fruits and commonly used in cosmetics and fragrances, has been increasingly employed as a solvent for 'natural' cleaning products. Supercritical carbon dioxide is another alternative solvent used in a multifariousness of reactions, ranging from decaffeination of coffee to dry out cleaning.

A full discussion of specific solvents can be found throughout this encyclopedia.

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Trade Associations

S. Nikfar , in Encyclopedia of Toxicology (Third Edition), 2014

Halogenated Solvents Industry Brotherhood, Inc.

The Halogenated Solvents Industry Alliance, Inc. was formed in 1980 by a grouping of executives in the chlorinated solvents industry to meet the growing challenges of government regulation. HSIA is dedicated to serving the interests of the halogenated solvents industry, interests that include solvent equipment manufacturers, and producers, distributors, and commercial users of halogenated solvents. By working together, the halogenated solvents industry and HSIA protect industry interests and promote the safe and responsible use of chlorinated solvents. HSIA represents companies that industry, distribute, and use methylene chloride, perchlorethylene, trichlorethylene, with bully emphasis on staying ahead of and actively participating in the decision-making process. The staff collect and analyze data nigh halogenated solvents and government plans and activities relating to them, and relay that information to HSIA lath and committee members. HSIA communicates with the European Chlorinated Solvent Association (ECSA) and the Japan Association for Hygiene of Chlorinated Solvents (JAHCS). ECSA was formed in the 1970s by the leading chlorinated solvent manufacturers in Europe. Like HSIA, the goals of ECSA and JAHCS are to support safe use of chlorinated solvents and to encourage balanced regulation.

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Current Developments in Excipient Science

Mousumi Kar , ... Rakesh K. Tekade , in Basic Fundamentals of Drug Delivery, 2019

ii.2.2.one Solvents

Solvents are the substances that are used to dissolve the solutes used in the formulation. These solutes may be solids, liquids, or gaseous in nature. Thus, solvents are used to get a solution upon interacting the solute with a suitable solvent. A solvent may act in many ways, depending on the properties of the solvent, such as:

•

molecular shape and size of the solvent molecule

•

polar/nonpolar nature

•

the concentration of the solvent molecules

•

temperature

•

pressure, etc.

The drug properties also affect the activity of the solvent and hence selection of the solvent in the pharmaceutical formulation is an important step toward getting a uniform and stable system. Commonly, it has been observed that the solvent properties increment with the ascension in temperature.

Almost of the drugs that are used in pharmaceuticals are those with low solubility, hence solvents are used significantly. A prediction on drug solubility is calculated using solid–liquid. A solvent may be solid, liquid, or gas, but it is unremarkably a liquid for liquid pharmaceutical preparations (Hirshfield et al., 2014).

Solvents are broadly classified every bit:

1.

Based on their affinity toward the water

a.

Polar

b.

Nonpolar

2.

Based on their miscibility with water

a.

Water-miscible

b.

Water-immiscible

3.

Based on their origin

a.

Natural

b.

Synthetic

In that location are various parameters that affect the process of solubility and the selection of a suitable solvent for the design of liquid dosage grade that include polarities of solute and solvent, thermodynamics of the process of dissolution, temperature of the prepare-up, pKa and ionization of solute and solvent, pH of the organisation nether study, and likewise on the nature of solute and solvents. Dissolution is a thermodynamically favorable process and is required and then that the solute is dissolved in a solvent. When the solvent is polar in nature, then solutes that are polar in nature will be attracted more every bit compared with the solutes that are uniform that are nonpolar in nature. Hence, it is observed that when the molecular surface size of the solute is more than, the solubility is less in polar solvents. More often than not used solvents in liquid dosage forms are water, alcohol, ethanol (94.nine%–96%), 70% ethyl alcohol, propylene glycol, glycerol, oils (fixed oils, mineral oils, paraffin), etc. (Kerton and Marriott, 2013; Grodowska and Parczewski, 2010).

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Organic Applications of UV-Visible Absorption Spectroscopy

Alison A. Edwards , Bruce D. Alexander , in Encyclopedia of Spectroscopy and Spectrometry (Second Edition), 2010

Solvent

The solvent used for sample grooming must produce a true solution of the sample and non absorb in the wavelength region existence studied, every bit this would atomic number 82 to assimilation bands of the sample being masked. Limiting wavelengths for solvent absorptions (cutoffs) for mutual spectroscopic solvents are listed in Table iii, but information technology should be noted that the exact cutoff volition depend on the solvent grade/specification used. Spectroscopic grade solvents can be expensive simply tin extend the spectral window that is attainable compared to 'standard' analytical or reagent-grade solvents.

Table 3. Wavelength cutoffs for spectroscopic class solvents

Solvent Wavelength (nm)
Water 180
Acetonitrile 190
n-Hexane 190
Cyclohexane 195
Isohexane 195
Methanol 205
Ethanol 205
Tetrahydrofuran 215
Diethyl ether 220
Dichloromethane 232
Chloroform 245
Carbon tetrachloride 265
Benzene 280

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Bioextraction of astaxanthin adopting varied techniques and downstream processing methodologies

Xiang Cheng , Mahfuzur Shah , in Global Perspectives on Astaxanthin, 2021

3.8 Supramolecular solvent extraction

SUPRAS are composed of nanostructured fluids of amphiphiles (east.1000., alkanols, carboxylic acids, alkyl sulfates, and alkyl phenols). SUPRAS-NLCs-based extraction showed effective extraction of astaxanthin from H. pluvialis (71%) in comparing with supercritical fluid extraction (SFE) [42] . Additionally, these SUPRAS-NLC solvents were able to preserve the antioxidant activity of astaxanthin with 180-day stability at four°C. Nevertheless, an optimal choice of SUPRAS amphiphiles that fulfill the requirements in extraction, stabilization, and encapsulation of astaxanthin would be required by this approach.

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Handbook of Pharmaceutical Assay by HPLC

Christopher Pohl , in Separation Scientific discipline and Technology, 2005

ane Solvents in Ion Substitution Eluent Systems

Solvents are often utilized in ion chromatography. Although solvents do non directly affect retention in ion substitution, solvents tin influence hydration of ions in the mobile phase and solvation of the ion exchange site in the stationary phase. In general, the effect of solvent is to reduce retention, predominantly affecting ions which are poorly hydrated or hydrophobic. In some cases, the addition of solvents can significantly alter selectivity, especially in the case of the coeluting analytes where one of the analytes contains a hydroxyl functional group (see Figure 8). Even so, solvents are more often than not but employed in cases where totally aqueous eluents systems are ineffective. Not simply are solvent-based eluent systems more expensive, solvents tin can result in suppressor damage when the suppressor is used in the electrolytic mode: They can also by and large issue in decreased conductivity detection sensitivity and, in some cases, can cause meaning harm to commercially available stationary phases (run into Table 1 for details).

Figure 8. Effect of methanol on the slope separation of inorganic anions and organic acids on an IonPac(r) ASII-HC and an AGII-HC column. Columns: four × 250 mm IonPac ASII-HC and four×50 mm AGII-HC. Menstruation rate: i.5 mLmin−ane. Temperature: 30°C. Injection volume: x μL. Detection: suppressed conductivity utilizing the Anion Self Regenerating Suppressor (4 mm), external water style. Ions: i—quinate (10 mg Fifty−1); 2—fluoride (three mg Fifty−1); 3—lactate (x mgL−1); 4—acetate (10 mgL−1); 5 — glycolate (10 mg L−1); half dozen—propionate (10 mg L−i); seven—formate (10 mg Fifty−1); viii—butyrate (ten mgL−1); ix—pyruvate (10 mgL−1), 10—valerate (x mgL−1), eleven—galacturonate (x mgL−1); 12—monochloroacetate (10 mgL−i); thirteen—bromate (10 mgL−ane); 14 — chloride (five mgL−1); 15—nitrite (ten mgL−i); 16—sorbate (10 mgL−1); 17—trifluoroacetate (10 mgL−1); eighteen—bromide (10 mgL−1); nineteen—nitrate (10 mgL−1); 20—glutarate (x mgL−1); 21—succinate (fifteen mgL−1); 22—maiate (15 mgL−ane); 23—carbonate (twenty mgL−1); 24—malonate (15 mgL−i); 25—tartrate (fifteen mgL−1); 26—maleate (15 mgL−1); 27—fumarate (xv mgL−1); 28—sulfate (15 mgL−one); 29—oxalate (xv mgL−one); 30—ketomalonate (20 mgL−1);31 —tungstate (20 mgL−1);32—phosphate (20 mgL−1); 33—citrate (xx mgL−1); 34—isocitrate (twenty mgL−1); 35—cis-aconitate and 36—trans-aconitate(20 mgL−1 combined). Eluent (a and b): sodium hydroxide: 1 mM from 0 to 8 min, one to 30 mM from viii to 28 min, thirty to 60 mM from 28 to 38 min. (b) Methanol: 10% from 0 to 8 min, 10% to xx% from 8 to eighteen min, 20% from eighteen to 28 min, 20% to x% from 28 to 38 min.

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Chemistry/Trace/Paint and Blanket

50.(Brun-Conti) Bough , in Encyclopedia of Forensic Sciences (Second Edition), 2013

Solvents

Solvents do not provide the blanket with any 'protection' qualities per se. However, the solvent is an important component of the paint, permitting ease of application to the surface or substrate it is designed to protect. With the exception of powder coatings, solvents are nowadays in all other coatings. The current trend in the coatings industry is to use equally little solvent equally possible. Water is an exception to this, as the evaporation of water is not seen as harmful to the environment. One of the purposes of a solvent is to solubilize the resin and to adjust the viscosity of the paint. However, in some paint systems, emulsions and latex paints in particular, the solvent is a carrier for the resin particles and is used by and large as a diluent for ease of application.

The solvent, also referred to as a 'thinner' or 'reducer,' will also affect the advent of the terminal film. The power of the paint to remain on a vertical surface without dripping or 'tearing' is achieved by using a faster evaporating solvent. Conversely, the ability of the pigment to remain on a horizontal surface long plenty to form a glossy film, and non dry out too quickly to form a puckered or 'orange-peeled' appearance, is accomplished by making use of a slower evaporating solvent. Pigment chemists may use a number of different solvents in a formulation to achieve the aforementioned qualities of the wet pigment. Solvents are likewise used to adjust paint for the environmental weather condition in which the pigment is to be used. The solvent bundle for an automotive pigment which volition be applied in a plant that is cool and dry may exist very dissimilar than the solvent package for the same paint that is to be sprayed in a institute in a humid area of the country.

As stated previously, environmental concerns are causing a trend in the paint industry to apply less solvent. Measuring the volatile organic components (VOCs) of paint is done by weighing a sample of paint earlier and after drying. The difference is the %VOC. H2o is non considered a VOC. The %VOC is regulated by the Environmental Protection Bureau (in the U.s.a.).

Solvents used in varying degrees in the paint industry are classified into the following groups: hydrocarbons, terpenes, oxygenated solvents, furans, nitroparaffins, and chlorinated solvents. Solvents are called for their solvency, volatility, odor, and toxicity. The solvency of a solvent is related to its ability to dissolve the flick-forming resin into solution. Volatility is related to the rate of evaporation of a solvent. The smell of a solvent is disquisitional for interior merchandise sales products since homeowners or part workers do non want a lingering 'solvent odor' from a newly applied blanket. Olfactory property has less of an impact in an industrial setting. Certain solvents, such as nigh chlorinated solvents and benzene, are considered toxic, and therefore are rarely used in coatings. Blanket chemists endeavor to apply as little solvent every bit possible when formulating pigment.

Terpene solvents are obtained from pino trees and consist of mixtures of unsaturated cyclic compounds containing 10 carbon and xvi hydrogen atoms. They are currently used in express amounts considering of both their potent odor and the availability of solvents with better solvency. Hydrocarbon solvents consist of just carbon and hydrogen and come up primarily from the petroleum industry. Classifications include aliphatics (consisting of normal paraffins and isoparaffins), naphthenes (cycloparaffins), aromatics, and olefins. Oxygenated solvents are those that incorporate not only carbon and hydrogen just also oxygen. The iv types widely used in the coatings industry are alcohols, esters, ketones, and glycol ethers. Glycol ether is peculiarly important because information technology is found to be a good substitute for effluvious hydrocarbons and is miscible in water, making it a vital solvent for the movement toward more than environmentally friendly paints. Furans, nitroparaffins, and chlorinated solvents are used in limited amounts and in specialized situations.

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Design and fabrication methods for biocomposites

50.K. Cardon , ... A. Gloria , in Biomedical Composites (Second Edition), 2017

2.4.1 Solvent casting

Solvent casting is a simple method for the creation of elementary shapes similar apartment sheets that is executed at room temperature. Advantages include the ease of fabrication, the lack of a need for specialised equipment, and the low processing temperatures. Disadvantages include the possible retention of toxic solvent within the polymer, the limited geometries accessible, and the possible denaturation of natural proteins by the solvent ( Rutkokswi et al., 2002).

In short, a polymer is dissolved in a solvent in a concentration that will be dependent on the required viscosity and backdrop of the solvent-cast picture show. This solution is then cast onto a surface (e.1000. glass plate, or Teflon) and allowed to dry. The length of the drying phase volition exist dependent on the volatility of the solvent and the thickness of the flick. Removal of the solvent may be enhanced by a secondary drying step nether vacuum. Once the solvent has evaporated from the film, it is removed from its recipient surface and is ready for use.

The distribution of the composing material elements is entirely dependent on the material ratios of the biocomposite earlier solution, and cannot be controlled geometrically during the solvent casting process. Hence this method is suitable for the production of chemical compound biocomposite structures, but not for multimaterial products. Solvent-cast sheets can even so exist combined with other parts to create more complex constructs (Ikada, 2006).

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Dyes and Colorants

S. Nikfar , M. Jaberidoost , in Encyclopedia of Toxicology (Third Edition), 2014

Solvent Dyes

Solvent dyes are soluble in organic solvents such as benzene, gasoline, booze, acetone, oils, fats, and waxes, and they are usually used as a solution in an organic solvent. They are used to color some organic solvents such as hydrocarbon fuels, waxes, lubricants, plastics, and other hydrocarbon-based nonpolar materials. They are ofttimes used for imitation aureate and other transparent metallic imitations and for coloring forest stains and varnishes, lacquers, printing and writing inks, butter and margarine, and plastics and resins. Some of the more popular are Solvent Crimson 24, Solvent Red 26, Solvent Red 164, Solvent Yellow 124, and Solvent Blueish 35. The structure of red and yellow solvent dyes is often the aforementioned as that of asazo dyes and green and blue dyes have a structure similar to anthraquinone dyes.

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Separation Methods in Drug Synthesis and Purification

Huba Kalász , ... Klára Fifty. Valkó , in Handbook of Analytical Separations, 2020

10.3.1 Optimization of solvent systems

Solvent system optimization tin be done on the basis of trial and mistake, according to literature data, or the intuition and experience of the chromatographer [ l]. The mobile-phase optimization procedure is based on Snyder'south solvent characterization [51] and is called the PRISMA system [50], which uses a three-step optimization procedure. The proper stationary phase and the possible individual solvents are chosen, and their combination is selected by means of the PRISMA model, while this combination is adapted to the selected technique (e.thousand., FF-TLC or saturated immersion mode, etc.).

Nyiredy [50] suggested the selection and testing of 10 neat solvents with various solvent strengths from Snyder's eight selectivity groups [51], preferably each one beingness miscible with hexane (solvent strength about 0). These solvents and their solvent strength according to Snyder are diethyl ether   =   2.eight (group I); ii-propanol   =   3.9, 1-propanol   =   4.0 and ethanol   =   4.3 (group II); tetrahydrofuran   =   4.0 (grouping Three); acetic acrid   =   6.0 (group Four); dichloromethane   =   three.i (grouping V); ethyl acetate   =   iv.iv and dioxane   =   iv.viii (group VI); toluene   =   2.iv (grouping Seven) and chloroform   =   4.ane (group 8). To split nonpolar compounds, the solvent strength can exist decreased by hexane, while to dissever polar compounds, the solvent strength can exist increased past adding depression concentrations of either h2o (solvent forcefulness is 10.2) or some other polar solvent. Therefore, the R F values of the sample components can exist brought within the range of 0.ii–0.8 [50]. The next step in Nyiredy's PRISMA system is to construct a tripartite PRISMA model, which correlates the solvent strength with the selectivity of the solvent organization. It can optimize between two and v solvent systems. The upper portion of the frustum serves to optimize polar compounds, the centre portion does and then for nonpolar compounds, while the lower part symbolizes the modifiers. This optimization process is detailed in the literature [51,52].

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