Drying under vacuum

The case that the evaporation temperature is decreasing when the process pressure is lowered gives a lot of advantages especially for the contact drying. 

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Carboxymethyl)tr(methy(ammonlum chloride hydrazlde (Reagent T ). A cooled soKilion of ethyl chioroacetate (984 g, 6.65 mol) was treated with irimethylamine (200 g, 3.39 mol). After 12-24 h a second portion of trimethylamlne (200 g, 3.39 mol) was added. After complete consumption of ethyl chioroacetate, hydrazine (4C0 g) was added. The product was tillered and dryed under vacuum (H2SO4) to afford 1100 g of T (90%). 

It was recrystd twice as the free base from ethanol or methanol/water by dropwise addition of NaOH (less than O.IM). The ppte was washed with water and dried under vacuum. It was dissolved in CHCI3 and chromatographed on alumina the main sharp band was collected, concentrated and cooled to -20 . The ppte was filtered, dried in air, then dried for 2h under vacuum at 70°- [Stone and Bradley J Am Chem Soc 83 3627 1961 , Blauer and Linschitz J Phys Chem 66 453 1962.]... 

Amino-4-methyIpyridine [695-34-1 ] M 108.1, m 99.2 , b 230 , pK 7.48. Crystd from EtOH or a 2 1 benzene/acetone mixture, and dried under vacuum. 

Amino-6-methyIpyridine [1824-81-3] M 108.1, m 44.2 , b 208-209 , pK 7.41. Crystd three times from acetone, dried under vacuum at ca 45 . After leaving in contact with NaOH pellets for 3h, with occasional shaking, it was decanted and fractionally distd [Mod, Magne and Skau J Phys Chem 60 1651 1956]. Also recrystd from CH2CI2 by addition of pet ether. [Marzilli et al. J Am Chem Soc 108 4830 1986.]... 

Anthrone [90-44-8] M 194.2, m 155 , pK -5.5 (aq H2SO4). Crystd from a 3 1 mixture of benzene/pet ether (b 60-80 ) (10-12mL/g), or successively from benzene then EtOH. Dried under vacuum. 

Antipyrine [2,3-dihydro-l,5-dimethyl-3-oxo-2-phenylpyrazole] [60-80-0] M 188.2, m 114 , b 319 , pK 1.45. Crystd from EtOH/water mixture, bcnzene, bcnzene/pet ether or hot water (charcoal), and dried under vacuum. 

B-L-Arabinose (natural) [87-72-9] M 150.1, m 158 , [a]o +104 (c 4, H2O after 24h). Crystd slowly twice from 80% aq EtOH, then dried under vacuum over P2O5. 

Benzoylacetone (l-pbenyl-l,3-butanedione) [93-91-4] Et20 or MeOH and dried under vacuum at 40 . 

Benzoyl peroxide [94-36-0] M 242.2, m 95°(dec). Dissolved in CHCI3 at room temperature and ppted by adding an equal volume of MeOH or pet ether. Similarly ppted from acetone by adding two volumes of distilled water. Has also been crystd from 50% MeOH, and from diethyl ether. Dried under vacuum at room... 

Bis-(chloromethyl)durene [3022-16-0] M 231.2, m 197-198 . Crystd three times from benzene, then dried under vacuum in an Abderhalden pistol. 

Bis-(4-nitrophenyI) ether [101-63-3] M 260.2, m 142-143 . Crystd twice from CgH6, and dried under vacuum. 

Butyramide [514-35-5] M 87.1, m 115 , b 230 . Crystd from acetone, benzene, CC -pet ether, 20% EtOH or water. Dried under vacuum over P2O5, CaCl2 or 99% H2SO4. 

Cetylamide [629-54-9] M 255.4, m 106-107", b 235-236"/12mm. Crystd from thiophene-free benzene and dried under vacuum over P2O5. 

Crystd from thiophene-free benzene and dried under vacuum over P2O5. 

Chloronaphthalene [91-58-7] M 162.6, m 61°, b 264-266°. Crystd from 25% EtOH/water and dried under vacuum. 

Choline chloride [67-48-1] M 139.6, m 302-305 (dec). Extremely deliquescent. Purity checked by AgN03 titration or by titration of free base after passage through an anion-exchange column. Crystd from absolute EtOH, or EtOH-diethyl ether, dried under vacuum and stored in a vacuum desiccator over P2O5 or Mg(C104)2. 

Cyanuric chloride (TCT, 2,4,6-trichloro-l,3,5-triazine) [108-77-0] M 184.4, m 146-149 , 154 , h 190 . Crystd from CCI4 or pet ether (b 90-100°), and dried under vacuum. Recrystd twice from anhydrous benzene immediately before use [Abuchowski et al.J Biol Chem 252 3582 1977]. 

Cyclohexane-l,2-diaminetetraacetic acid (H2O CDTA) []329]-6]-7] M 364.4, pK 1.34, pK2 3.20, PK3 5.75 (6.12), PK4 9.26 (12.35). Dissolved in aq NaOH as its disodium salt, then pptd by adding HCl. The free acid was filtered off and boiled with distd water to remove traces of HCI [Bond and Jones Trans Faraday Soc 55 1310 7959]. Recrystd from water and dried under vacuum. 

Decyltrimetbylammonium bromide [2082-84-0] M 280.3, m 239-242 . Crystd from 50% (v/v) EtOH/diethyl ether, or from acetone and washed with ether. Dried under vacuum at 60 . Also recrystd from EtOH and dried over silica gel. [McDonnell and Kraus J Am Chem Soc 73 2170 1952 E)earden and Wooley J Phys Chem 91 2404 1987.]... 

Dibenzo-18-crown-6 [14187-32-7] M 360.4, m 163-164 . Crystd from benzene, -heptane or toluene and dried under vacuum at room temperature for several days. [Szezygiel J Phys Chem 91 1252 1987.]... 

Dibenzofuran [132-64-9] M 168.2, m 82.4 . Dissolved in diethyl ether, then shaken with two portions of aqueous NaOH (2M), washed with water, separated and dried (MgS04). After evaporating the ether, dibenzofuran was crystd from aq 80% EtOH and dried under vacuum. [Cass et al. J Chem Soc 1406 7958.] High purity material was obtained by zone refining. 

Di-tert-butyl-p-cresol (2,6-di-tert-butyl-4-methylphenol, butylatedhydroxytoluene, BHT) [128-37-0] M 230.4, m 71.5 , pK 12.23. Dissolved in n-hexane at room temperature, then cooled with rapid stirring, to -60°. The ppte was separated, redissolved in hexane, and the process was repeated until the mother liquor was no longer coloured. The final product was stored under N2 at 0° [Blanchard J Am Chem Soc 82 2014 7960]. Also crystd from EtOH, MeOH, benzene, n-hexane, methylcyclohexane or pet ether (b 60-80°), and dried under vacuum. 

Dihydroxybenzoic acid [303-07- ] M 154.1, m 167"(dec), pK 1.05. Dissolved in aqueous NaHC03 and the soln was washed with ether to remove non-acidic material. The acid was ppted by adding H2SO4, and recrystd from water. Dried under vacuum and stored in the dark [Lowe and Smith J Chem Soc, Faraday Trans I 69 1934 1973],... 

Dimethoxybenzene [150-78-7] M 137.2, m 57.2-57.8 . Steam distd. Crystd from hexane or benzene, and from MeOH or EtOH but these are wasteful due to high solubilities. Dried under vacuum. Also sublimes under vacuum. 

Dinitrobenzene [100-25-4] M 168.1, m 173 . Crystd from EtOH or ethyl acetate. Dried under vacuum over P2O5. Can be sublimed in a vacuum. 

Dinitrobiphenyl [1528-74-1] M 244.2, m 240.9-241.8 . Crystd from benzene, EtOH (charcoal) or acetone. Dried under vacuum over P2O5. 

Dinitrotoluene [121-14-2] M 182.1, m 70.5-71.0 . Crystd from acetone, isopropanol or MeOH. Dried under vacuum over H2SO4. Purified by zone melting. Could be EXPLOSIVE when dry. 

Diphenylamine [122-39-4] M 169.2, m 62.0-62.5 , pK 0.77 (aq H2SO4). Crystd from pet ether, MeOH, or EtOH/water. Dried under vacuum. 

Duroquinone (tetramethylbenzoquinone) [527-17-3] M 164.2, m 110-111 . Crystd from 95% EtOH. Dried under vacuum. 

Ethoxynaphthalene [93-18-5] M 172.2, m 35.6-36.0 , b 142-143 /12mm. Crystd from pet ether. Dried under vacuum or distd in a vacuum. 

Glutaric acid [110-94-1] M 132.1, m 97.5-98", pK 4.35, pK2 5.40. Crystd from benzene, CHCI3, distilled water or benzene containing 10% (w/w) of diethyl ether. Dried under vacuum. 

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