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129:. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achieve perfect dryness; anhydrous compounds gradually absorb water from the atmosphere so they must be stored carefully.
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or a column purification system. Molecular sieves are far more effective than most common methods for drying solvents and are safer and require no special equipment for handling. Column solvent purification devices (generally referred to as Grubb's columns) recently became available, reducing the
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In many cases, the presence of water can prevent a reaction from happening, or cause undesirable products to form. To prevent this, anhydrous solvents must be used when performing certain reactions. Examples of reactions requiring the use of anhydrous solvents are the
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Anhydrous solvents are commercially available from chemical suppliers, and are packaged in sealed containers to maintain dryness. Typically anhydrous solvents will contain approximately 10 ppm of water and will increase in wetness if they are not properly stored.
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Williams, D. Bradley G.; Lawton, Michelle (2010-12-17). "Drying of
Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants".
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Solvents have typically been dried using distillation or by reaction with reactive metals or
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hazards (water reactive substances, heat) from the classical dehydrating methods.
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ammonia, to distinguish it from its solution in water, household
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Many salts and solids can be dried using heat, or under vacuum.
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or a similar drying agent to remove most remaining water.
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Reactions which produce water can be kept dry using a
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can also be used to store reagents in dry conditions.
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365:. Archived from the original on September 4, 2006.
363:"Guidelines for solvent purification at UC Davis"
261:, to distinguish it from its solution in water,
199:Organic solutions can be dried using a range of
224:standard conditions of temperature and pressure
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234:is prefixed to the name of the substance:
222:Several substances that exist as gases at
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109:Learn how and when to remove this message
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250:, also known as ammonium hydroxide.
226:are commonly used as concentrated
210:Anhydrous acetic acid is known as
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375:: CS1 maint: unfit URL (
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271:Dean–Stark apparatus
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459:Chemical properties
212:glacial acetic acid
167:Liquids or solvents
16:Waterless substance
283:Air-free technique
125:if it contains no
433:www.chem.ucla.edu
391:"Drying Solvents"
333:10.1021/jo101589h
327:(24): 8351–8354.
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139:Desiccators
58:"Anhydrous"
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306:References
154:silica gel
146:desiccants
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99:June 2010
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277:See also
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