Drying agent calcium chloride

After drying over quicklime, calcium oxide CaO, the ammonia is collected by upward delivery. (N.B. Both of the common drying agents, calcium chloride and concentrated sulphuric acid, combine with the gas.)... 

Take a portion of the crystals (or some of the material in crude form) and allow it to effloresce freely in a warm place. Put it in a roomy desiccator in place of the usual drying agent (calcium chloride). Place the wet crystals in a suitable container and support them over the effloresced material in the desiccator (Fig. 2). There are... 

The absolute humidity of air refers to the mass of water vapour actually present in unit vol., and it is determined by passing a known vol. of air over a suitable drying agent—calcium chloride, phosphorus pentoxide, etc. (1. 7, 2)—and... 

After the perbenzoic acid is liberated with sulfuric add, it may be extracted from the aqueous solution with any appropriate organic solvent (e.g. ether or ethyl acetate). Even if concentrated solutions of perbenzoic acid are requirdl, it is better to apply the amount of solvent specified (or more) and then to concentrate the solution under reduced pressure at a temperature not above 30-35°. The solution may, but need not, be dried before concentration. Anhydrous sodium sulfate is the only satisfactory drying agent. Calcium chloride sometimes causes a sudden decomposition of the peracid. 

Calcium forms the calcium(II) cation Ca in aqueous solutions. Its salts are normally white powders and form colourless solutions, unless the anion is coloured. Solid calcium chloride is hygroscopic and is often used as a drying agent. Calcium chloride and calcium nitrate dissolve readily in ethanol or in a 1 + 1 mixture of anhydrous ethanol and diethyl ether. 

In a 500-ml. three-necked round-bottomed flask equipped with a sealed stirrer, a reflux condenser, and a dropping funnel are placed 36 g. (0.45 mole) of ethylene chlorohydrin (Note 1), 5 ml. of concentrated sulfuric acid, and 35 ml. of benzene. The mixture is warmed on a water bath, and to it is added, with efficient stirring, a solution of 55 g. (0.30 mole) of benzhydrol (Note 2) in 65 ml. of benzene (Note 3) during 30-50 minutes. The reaction mixture is heated at the reflux temperature for an additional 4 hours with stirring. To the cooled mixture is added about 35 ml. of benzene, and the combined benzene layer is washed with water and dried over calcium chloride. The drying agent is removed, the benzene is evaporated, and the residue is... 

This Grignard reaction is particularly difficult to initiate and depends greatly on the purity of the neopentyl chloride. Commercial neopentyl chloride [Eastern] is stirred over four consecutive portions of concentrated sulfuric acid for a period of 6h each followed by 1 h for the mixture to completely settle before draining off the darkened acid layer. The fourth portion of acid is only slightly colored. The clear neopentyl chloride is washed with water followed by aqueous sodium bicarbonate solution, dried over calcium chloride, then filtered from the drying agent before use. Pure neopentyl chloride distils at 83 to 84 °C and is inert to concentrated sulfuric acid at room temperature. 

The oily layer is separated from the aqueous layer, the aqueous layer is extracted with two 200-ml. portions of ether, and the combined extracts and oil are dried over calcium chloride. The drying agent is removed by filtration, and the ether is distilled on a water bath finally, all low-boiling material is removed from the mixture on a boiling water bath under the lowest pressure obtainable with a water pump (Note 6). The nitrosoaminoketone which remains in the flask is sufficiently pure for the preparation of diazomethane (Note 7). The yield is 221-257 g. (70-80% based on mesityl oxide). 

Calcium chloride, CaCl CaCl. H O CaCl. -6H2O, used as cheap drying agent Calcium oxide, CaO, used in water treatment Copper sulfate, CuSO, used as a dehydrating agent... 

The most powerful drying agents are sodium and phosphorus pentoxide. The use of the former is evidently limited to those substances which do not react with the metal. Sodium is used to remove the last traces of water only, the substances being previously dried with calcium chloride which removes most of the water. 

Amino-2-methylpropionitrile 979 cf 980 Dry ammonia is led into freshly prepared acetone cyanohydrin, the temperature not being allowed to rise above 65°. The solution is kept for some time at 60°, then the amino nitrile formed is taken up in ether. Because of the ease with which this compound decomposes, the solution must next be very thoroughly dried over calcium chloride. Then distillation in a vacuum affords a 64% yield of the amino nitrile, b.p. 48-50°/l 1 mm. It is, however, better to add a drying agent (sodium sulfate) to the mixture while the ammonia is being passed in the yield is then greater (up to 85%). 

The preceding method removes water, ethanol, and acetic acid. Drying over calcium chloride is not recommended. Ethyl acetate containing abnormal amounts of ethanol should be shaken with saturated sodium chloride solution and dried over magnesium sulfate before being treated with acetic anhydride.35 The ester can be dried by phosphoric oxide if it is decanted from the drying agent before distillation. 

In a variation of this procedure, the monomer is extracted twice with dilute aqueous sodium hydroxide, twice with water, then dried over calcium chloride, refluxed with calcium hydride, and distilled from this drying agent [32]. 

Absorbent cotton (cotton wool). This material is an excellent drying agent for use in the so-called calcium chloride tubes, i.e., drying tubes, placed at the top of dropping funnels, reflux condensers, etc., to exclude moisture. It is more convenient than calcium chloride, and should preferably be dried in an oven at 100° before use. 

Calcium chloride cannot be used to dry the ethereal solution because it combines with aniline (and other amines) to form molecular compounds. The best drying agent is sodium or potassium hydroxide (pellet form). 

You see that vacuum adapter stuck to the top of the condenser in fig. 7a Well, a closer look at it in fig. 7b will show that it has some drying agent sandwiched between two cotton balls and the nipple (tee heel) sealed with plastic wrap or foil. The drying agent can be either a commercial product called Drierite or calcium chloride. This attachment is placed on top of a condenser when refluxing solutions that have no water in them and must remain that way during the time they are refluxed. All this is to prevent moisture in the outside air from coming into contact with the cold surface of the of the inside walls of the condenser. This will surely happen and the condensed outside-air water will drip down into the reaction flask and ruin the experiment. This is not so much a... 

Stage one - the reaction happens in the form of a reflux with a dry set-up. You will need a 2000ml reaction flask, a condenser and a drying tube packed with calcium chloride or other drying agent. The reaction needs to be stirred in a big way, so before we add the ingredients make sure you have a clean stirrer bar ready, I prefer the eggy shape bars as they tend to be less noisy. 

After drying or decomposing a sample, it should be cooled to room temperature in a desiccator to avoid the readsorption of moisture. A desiccator (Figure 2.9) is a closed container that isolates the sample from the atmosphere. A drying agent, called a desiccant, is placed in the bottom of the container. Typical desiccants include calcium chloride and silica gel. A perforated plate sits above the desiccant, providing a shelf for storing samples. Some desiccators are equipped with stopcocks that allow them to be evacuated. 

By-product water formed in the methanation reactions is condensed by either refrigeration or compression and cooling. The remaining product gas, principally methane, is compressed to desired pipeline pressures of 3.4—6.9 MPa (500—1000 psi). Einal traces of water are absorbed on siHca gel or molecular sieves, or removed by a drying agent such as sulfuric acid, H2SO4. Other desiccants maybe used, such as activated alumina, diethylene glycol, or concentrated solutions of calcium chloride (see Desiccants). 

The polymerization is carried out at temperatures of 0—80°C in 1—5 h at a soHds concentration of 6—12%. The polymerization is terminated by neutralizing agents such as calcium hydroxide, calcium oxide, calcium carbonate, or lithium hydroxide. Inherent viscosities of 2-4 dL/g are obtained at 3,4 -dianiinodiphenyl ether contents of 35—50 mol %. Because of the introduction of nonlinearity into the PPT chain by the inclusion of 3,4 -dianiinodiphenyl ether kinks, the copolymer shows improved tractabiUty and may be wet or dry jet-wet spun from the polymerization solvent. The fibers are best coagulated in an aqueous equiUbrium bath containing less than 50 vol % of polymerization solvent and from 35 to 50% of calcium chloride or magnesium chloride. 

Class 1 drying agents (and zeoHtes, which are Class 4 desiccants) Hberate the largest amounts of heat and should be used with appropriate care. Calcium chloride is a Class 1 drying agent that reacts with water to form a hydrate ... 

Because calcium chloride has a number of hydrates, the one that is in equiUbrium with a saturated solution is a function of the temperature. In this case, the sohd is dissolved as it absorbs water to form the saturated solution, and three phases are present soHd, saturated solution, and vapor. Systems having these three phases, or two soHds and a vapor phase, have a constant vapor pressure at a given temperature. Therefore, Class 2 drying agents can be used to maintain a constant relative humidity. 

Fig. 2. Drying capacity of selected drying agents in liquid form. A represents lithium chloride B, calcium chloride C, sulfuric acid D, glycerol E, triethylene...

The original flask used for the enamine formation can be used after the attachment of a Y-shape tube fitted with a dropping funnel and a reflux condenser protected with a tube packed with a drying agent such as anhydrous calcium chloride. 

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