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Analytical Chemistry Trinidad & Tobago Lab Resources

SOLVENT DRYING AND DRYING AGENTS


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Properties of solvents and methods used for drying them using Solvent Drying Guide.

Removing water from Solvents


There are various ways of removing water and other impurities from a solution. This can become a major task once the used reagents are also sensitive towards water e.g. Grignard reagents or enolates. If water is one of the products, it also has a detrimental effect on the yield and/or reaction rate.

In such cases, drying agents like activated alumina¹, calcium hydride (CaH2), sodium metal (in combination with benzophenone which forms a dark blue ketyl radical), lithium aluminum hydride (LiAlH4) or phosphorous pentoxide (P4O10) are used to chemically destroy the water.

The drying agents commonly used in the organic laboratories are the anhydrous forms of calcium chloride (CaCl2), sodium sulfate (Na2SO4) Calcium sulfate (CaSO4 (as Drierite) and magnesium sulfate (MgSO4).

Organic liquids are considered to be wet if they contain water,but the organic liquid will still be a liquid after it is dried.

Activated Alumina


Activated alumina ¹ is a very porous form of aluminum oxide of high surface area which adsorbs liquids and gases without any change in form. Activated alumina will not soften or disintegrate when immersed in liquids. Activated alumina may be regenerated to its original adsorption efficiency by heating to a temperature between (177-316°C).

Activated alumina can be used for:
Reconditioning of mineral oils like transformer or insulating oils.
Removal of oil vapor mist from compressed air.
Drying of organic liquids to a moisture level of 10 ppm or below.
Drying of various liquids such as Benzene, Carbon Tetrachloride, Chlorobenzene, Ethyl Acetate, Transformer oil, Vegetable oils etc.




SOLVENT DRYING GUIDE


TO DRY


USE ONE OF THE FOLLOWING DRYING AGENTS

AlcoholsAnhydrous forms of potassium carbonate; anhydrous magnesium or calcium sulphate; quicklime.
Alkyl halides
Aryl halides		Anhydrous calcium chloride; anhydrous forms of sodium sulphate, magnesium sulphate, or calcium sulphate; sodium pentoxide.
Saturated and
Aromatic hydrocarbons		Anhydrous calcium chloride or sulphate; metallic sodium; phosphorus pentoxide.
AldehydesAnhydrous sodium sulphate; anhydrous magnesium or calcium sulphate.
KetonesAnhydrous sodium sulphate; anhydrous magnesium or calcium sulphate; anhydrous potassium carbonate.
Organic bases
(amines)		Solid potassium or sodium hydroxide; quicklime; barium oxide.
Organic acidsAnhydrous sodium sulphate; anhydrous magnesium or calcium sulphate.


Solvents: Properties and Drying agents


Solvent Boiling Pt.
°C		 Density Flash Pt.
°C		 Drying agent
Acetone 56 0.791 -18 K2CO3; Molecular sieve 0.3nm; CaCl2
Acetic acid 118 1.049 +40 P2O5; CuSO4
Acetic anhydride 136 1.082 +49 CaCl2
Acetonitrile 82 0.782 +6 CaCl2; P2O5; K2CO3; calcium hydride; Molecular sieve 0.3nm
Aniline 184 1.022 +76 KOH; BaO
Anisole 154 0.995 +51 CaCl2; Na; distillation
Benzene 80 0.879 -10 CaCl2; distillation; Na; Pb/Na; ; calcium hydride; Na wire; Molecular sieve 0.4nm
1-Butanol 117 0.810 +29 K2CO3; distillation
2-Butanol 100 0.808 +24 K2CO3; distillation
tert-Butanol 82 0.882 +11 CaO; Freezing
n-Butyl acetate 127 0.882 +33 MgSO4;
Carbon disulphide 46 1.263 -30 CaCl2P2O5;
Carbon tetrachloride 77 1.594 none distillation; P2O3; Pb/Na; Molecular sieve 0.4nm
Chlorobenzene 132 1.106 +29 CaCl2; distillation;P2O5
Chloroform 62 1.486 none CaCl2; P2O5; Pb/Na; Molecular sieve 0.4nm
Cyclohexane 81 0.799 none Na; Na/Pb; LiAlH4; Molecular sieve 0.4nm
Cyclohexanone 155 na na Distillation
Decahydronaphthalene
(Dekalin) 		~190 0.886 <54 CaCl2; Na; Pb/Na
Dichloromethane 40 1.325 none CaCl2; Pb/Na; calcium hydride; Molecular sieve 0.4nm
Dicyclopentadiene:
(cyclopentadiene dimer)		 170 na na Refractionation: distillate at 40 - 42°C. (Use at once! or keep in dry ice/acetone bath no longer than 1 Hr.)
Diethyl carbonate 126 0.975 +25 Na2SO4; K2CO3
Diethylene glycoldibutyl ether 225 0.885 +118 CaCl2; Na
Diethylene glycol dimethyl ether 155
165		 0.906 +70 CaCl2; Na
Diethyl ether 34 0.714 -40 CaCl2; Na; Pb/Na; LiAlH4; Na wire/benzophenone; Molecular sieve 0.4nm
Di-isopropyl ether 68 0.726 -23 CaCl2; Na; Molecular sieve 0.4nm
Dimethyl formamide 153 0.950 +62 distillation; Molecular sieve 0.4nm
Dimethyl sulfoxide 189 1.101 +95 distillation; Molecular sieve 0.4nm
1,4 Dioxane 101 1.034 +11.8 CaCl2; Na; Molecular sieve 0.4nm
Ethanol 79 0.791 +12 CaO; Mg; MgO; Molecular sieve 0.3nm
Ethyl acetate 77 0.901 -4 K2CO3; P2O5; Na2SO4; calcium hydride; Molecular sieve 0.4nm
Ethylenediamine:
(1-2 diaminoethane)		 118 na na Simple distillation.
Ethylene glycol 197 1.109 +111 distillation; Na2SO4
Ethylene glycol monoethyl ether 135 0.930 +41 distillation
Ethylene glycol monomethyl ether 125 0.965 +52 distillation
Ethyl formate 54 0.924 -20 MgSO4; Na2SO4;
Formamide 211 1.134 155 Na2SO4; CaO
Glycerol 290 1.260 +176 distillation
Heptane 98 0.684 -4 calcium hydride; Na wire
n-Hexane 69 0.659 -23 Na; Pb/Na; LiAlH4; calcium hydride; Na wire/benzophenone; Molecular sieve 0.4nm
Isobutanol 108 0.803 +28 K2CO3; CaO; Mg;
Isobutyl methyl ketone 117 0.801 +15.5-4 K2CO3;
Methanol 65 0.792 +11 Mg; CaO; Molecular sieve 0.3nm
Methyl acetate 57 0.933 -10 K2CO3; CaO;
1-Methyl-2-pyrrolidone 202 1.026 +95 Na2SO4; distillation; Molecular sieve 0.4nm
Methyl Ethyl ketone 80 0.806 -44 K2CO3;
Nitrobenzene 211 1.204 +92 CaCl2; P2O5; distillation;
n-Pentane 36 0.626 -49 Na; Pb/Na;calcium hydride; Na wire
Pet ether mixture na na calcium hydride; Na wire/benzophenone; Molecular sieve type 4A
1- Propanol 97 0.804 +15 CaO; Mg
2-Propanol 82 0.785 +12 CaO; Mg; Molecular sieve 0.3nm
Pyridine 116 0.982 +20 KOH; BaO; Molecular sieve 0.4nm
Tetrahydrofuran 66 0.887 -17.5 Molecular sieve 0.4nm
Tetrahydronaphthalene
(Tetralin)		 208 0.973   CaCl2; Na
Thionyl chloride 48 na na Redistill.
Toluene 111 0.867 +4 distillation; Ca; CaCl2; Na; Molecular sieve 0.4nm
Trichloroethylene 87 1.462 none distillation; Na2SO4; K2CO3
Xylene 137/140 -0.86 +25 distillation; Na; CaCl2; Molecular sieve 0.4nm



Reference: http://www.deltaadsorbents.com/activated_alumina_2.php


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