Information AboutSolvent |
| CATEGORIES ABOUT SOLVENT | |
| soil contamination | |
| solvents | |
| solutions | |
| chemical compounds | |
|
A solvent is a liquid that dissolves a solid, liquid, or gaseous Solute , resulting in a Solution . The most common solvent in everyday life is Water . The term '''organic solvent''' refers to most other solvents that are Organic Compound s and contain Carbon atoms. Solvents usually have a low Boiling Point and evaporate easily or can be removed by Distillation , thereby leaving the dissolved substance behind. Solvents should therefore not React Chemically with the dissolved compounds — they have to be Inert . Solvents can also be used to Extract Soluble compounds from a mixture, the most common example is the brewing of Coffee or Tea with hot water. Solvents are usually clear and colorless liquids and most of them have a characteristic odor. The Concentration of a solution is the amount of compound that is dissolved in a certain volume of solvent. The '''solubility''' is the maximal amount of compound that is soluble in a certain volume of solvent at a specified Temperature . Common uses for organic solvents are in Dry Cleaning (e.g. Tetrachloroethylene ), as Paint Thinner s (e.g. Toluene , Turpentine ), as nail polish removers and glue solvents ( Acetone , Methyl Acetate , Ethyl Acetate ), in spot removers (e.g. Hexane , Petrol Ether ), in Detergent s (citrus Terpene s), in Perfumes ( Ethanol ), and in Chemical Syntheses . POLARITY, SOLUBILITY, AND MISCIBILITY Solvents and solutes can be broadly classified into ''polar'' ( Salt s (e.g. Table Salt ) or Sugars (e.g. sucrose) dissolve only in very polar solvents like water, while strongly non-polar compounds like Oil s or Wax es dissolve only in very non-polar organic solvents like Hexane . Similarly, water and hexane (or Vinegar and salad oil) are not Miscible with each other and will quickly separate into two layers even after being shaken well. PROTIC AND APROTIC SOLVENTS Polar solvents can be further subdivided into polar Protic Solvent s and polar Aprotic Solvent s. Water (H-O-H), ethanol (CH3-CH2-OH), or Acetic Acid (CH3-C(=O)OH) are representative polar protic solvents. A polar aprotic solvent is acetone (CH3-C(=O)-CH3). In Chemical Reaction s the use of polar protic solvents favors the SN1 Reaction Mechanism , while polar aprotic solvents favor the SN2 reaction mechanism. BOILING POINT Another important property of solvents is their Boiling Point that also determines the speed of evaporation. Small amounts of low-boiling solvents like Diethyl Ether , Dichloromethane , or acetone will evaporate in seconds at room temperature, while high-boiling solvents like water or Dimethyl Sulfoxide need higher temperatures, an air flow, or the application of Vacuum for fast evaporation. DENSITY Most organic solvents have a lower Density than water. Therefore they are lighter and will separate on top of water. An important exception are many Halogen ated solvents like Dichloromethane or Chloroform that will sink to the bottom. This is important to remember when Partitioning compounds between solvents and water in a Separatory Funnel during chemical syntheses. CHEMICAL INTERACTIONS A solvent will create various weak chemical interactions with the solute in order to solubilize it. The most common of these interactions are the relatively weak Van Der Waals Interactions (induced dipole interactions), the stronger dipole-dipole interactions, and the even stronger Hydrogen Bonds (interaction between O-H or N-H hydrogens with O or N atoms). HEALTH AND SAFETY Most organic solvents are flammable or highly flammable, depending on their volatility. Exceptions are some chlorinated solvents like Dichloromethane and Chloroform . Mixtures of solvent vapors and air can Explode . Solvent vapors are heavier than air, they will sink to the bottom and can travel large distances nearly undiluted. Solvent vapors can also form in supposedly empty drums and cans, posing a Flash Fire hazard; hence empty containers of volatile solvents should be stored open and upside down. Ethers like Diethyl Ether and Tetrahydrofuran (THF) can form highly explosive Organic Peroxide s upon exposure to oxygen and light. These peroxides will concentrate during distillation due to their higher Boiling Point . Ethers have to be stored in the dark in closed canisters in the presence of stabilizers like BHT or over Sodium Hydroxide . Many solvents can lead to a sudden loss of consciousness if Inhaled in larger amounts. Solvents like diethyl ether and Chloroform have been used in medicine as Anesthetics and Narcotics for a long time. Ethanol is a widely used and abused Psychoactive Drug . Diethyl ether, chloroform, and many other solvents (e.g. from Gasoline or glues) are used recreationally in Glue Sniffing , often with harmful long term health effects like Neurotoxicity or Cancer . A major pathway to induce health effects arises from spills or leaks of solvents that reach the underlying soil. Since solvents readily migrate substantial distances, the creation of widespread Soil Contamination is not uncommon; there may be about 5000 sites worldwide that have major subsurface solvent contamination; this is particularly a health risk if Aquifer s are affected. Some solvents including chloroform and Benzene (an ingredient of Gasoline ) are Carcinogenic . Many others can damage internal organs like the Liver , the Kidneys , or the Brain . Methanol can cause internal damage to the Eye s including permanent blindness. General precautions
PROPERTIES TABLE OF COMMON SOLVENTS The solvents are grouped into non-polar, polar aprotic, and polar protic solvents and ordered by increasing polarity. The polarity is given as the Dielectric Constant . The Density of nonpolar solvents that are heavier than water is bolded. SEE ALSO
EXTERNAL LINKS
|
|
|