Editing Anhydrous (section)

==Liquids or solvents==
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 [[Grignard reaction]] and the [[Wurtz reaction]].

Solvents have typically been dried using distillation or by reaction with reactive metals or [[metal hydride]]s. These methods can be dangerous and are a common cause of lab fires. More modern techniques include the use of [[molecular sieve]]s 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.<ref>{{cite journal|last=Williams|first=D. Bradley G.|last2=Lawton|first2=Michelle|date=2010-12-17|title=Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants|journal=The Journal of Organic Chemistry|volume=75|issue=24|pages=8351–8354|doi=10.1021/jo101589h|pmid=20945830|issn=0022-3263}}</ref> Column solvent purification devices (generally referred to as Grubb's columns) recently became available, reducing the hazards (water reactive substances, heat) from the classical dehydrating methods.<ref name="grubb">{{cite web |title=Guidelines for solvent purification at UC Davis |url=http://fire.ucdavis.edu/main/ucdfdinfobull22.htm |url-status=unfit |archive-url=https://web.archive.org/web/20060904103225/http://fire.ucdavis.edu/main/ucdfdinfobull22.htm |archive-date=September 4, 2006}}</ref><ref>{{cite web|title=Drying Solvents|url=https://chem.libretexts.org/Ancillary_Materials/Demos%2C_Techniques%2C_and_Experiments/General_Lab_Techniques/Drying_Solvents}}</ref>

Anhydrous solvents are commercially available from chemical suppliers, and are packaged in sealed containers to maintain dryness.<ref>{{cite news|url=https://www.sigmaaldrich.com/chemistry/solvents/sureseal.html|title=New Aldrich Sure/Seal® packaging for Anhydrous Solvents and Air-Sensitive Reagents|work=Sigma-Aldrich|access-date=2018-03-26|language=en}}</ref> Typically anhydrous solvents will contain approximately 10 ppm of water and will increase in wetness if they are not properly stored.

Organic solutions can be dried using a range of [[desiccant|drying agents]]. Typically following a workup the organic extract is dried using [[magnesium sulfate]] or a similar drying agent to remove most remaining water.<ref>{{cite web|url=http://www.chem.ucla.edu/~bacher/Specialtopics/Drying%20Agents.html|title=Drying agents|website=www.chem.ucla.edu|access-date=2018-03-26}}</ref>

Anhydrous acetic acid is known as [[glacial acetic acid]].