Distillation, apparatus steam

Steaming-out the steam distillation apparatus. After the cleaned steam -distillation apparatus (Fig. 88) has been assembled, it is essential to pass steam through it for some time to remove readily soluble alkali. All the taps on the apparatus are opened and the water in the steam generator boiled vigorously. The steam will gradually pass into the apparatus. After a few minutes, the tap of the tap-funnel C may be closed and soon afterwards the tap Ti of the steam-trap finally the tap Tj of the funnel G may be closed, Steaming-out should then be continued for not less than one hour, the receiver J not being in place. 

Before each experiment the steam-distillation apparatus should be steamed-out for about half an hour this may be carried out while the digestion is taking place. 

Small scale apparatus with interchangeable ground glass joints (compare Section 11,56) are available commercially. One set of apparatus ( A) is based largely upon BlO and B14 joints, although occasionally a larger size joint is used as in the steam distillation apparatus shown in Fig. XII, 3, 1. 

Alternatively, use the following procedure in which triethylamine replaces potassium acetate as the basic catalyst. Place 2 1 g. (2-0 ml.) of purified benzaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of A.R. acetic anhydride in a 200 ml. round-bottomed flask, equipped with a short reflux condenser and a calcium chloride drying tube. Boil the solution gently for 24 hours—heating may be interrupted. Incorporate a steam distillation apparatus in the flask and steam distil until the distillate is no longer cloudy (about 100 ml.) and then collect a further 50 ml. of the distillate di ard the steam distillate. Transfer the residue in the flask to a 400 ml. beaker, add water until the vplume is about 200 ml., then 0 2 g. of decolourising carbon, and boil for a few minutes. Filter the hot solution, and acidify the hot filtrate with 1 1 hydrochlorioiaoid... 

Sodium -toluenesulfonate, 3, 37, 38 Splitting C C linkage, 4, 39 Splitting C Hg linkage, 7, 19 Stabilizer, 8, 56 Stannous chloride, 8, 96 Starch-iodide test 3, 7 79, 8, 42, 80 Steam distillation apparatus, 2, 0 Steam distillation, reduced pressure, 5, 80... 

Figure 8.2 Different apparatus used for steu distillation. A aodified Gaman steam distillation apparatus A, steam generation flask B, sample chamber C, splash head D, condenser B, delivery tube F, separatory funnel. B = micro steam distillation apparatus A, boiling flask B, collection bulb C, water return arm D, Condenser. C - steam distillation apparatus using a Dean and Stark type trap. D = Nielsen-Kryger steam distillation apparatus.

A simple steam-distillation apparatus such as that given by Fieser 3 4 is entirely satisfactory. It is usually necessary to heat the distillation flask with a steam bath or a small flame in order to minimize the accumulation of excess water in the flask. 

An ultraviolet spectrophotometric analysis is used to assay pseudoephedrine hydrochloride in tablets. A portion of finely powdered tablets equivalent to approximately 30 mg of pseudoephedrine hydrochloride is placed in a distilling flask which is part of a micro-steam distillation apparatus. Sodium chloride, water, and concentrated sodium hydroxide are added. A minimum of 30 ml of distillate is collected in a volumetric flask containing dilute hydrochloric acid. The flask is made to volume with distilled water and the absorbance of the solution is determined at 257 nm in 1 cm cells and compared to a solution of known concentration of NF Pseudoephedrine Hydrochloride Reference Standard.1... 

A steam distillation apparatus is shown on the right-hand side of Figure 10.7. This same apparatus can be used to determine ammonia in soil as described previously. A flow diagram for the determination of ammonia in soil using a Kjeldahl analysis is given in Figure 10.8 [6],... 

Much time can be saved by the use of the steam distillation apparatus described, especially when large quantities have to be handled. The above directions avoid the use of extraction methods, which not only consume more time but may lead to appreciable losses of material. If the downward condenser is of iron, the apparatus is even more. efficient and the time for the steam distillation is halved. 

Procedure. Steam is passed through the steam distillation apparatus for 20-30 min. Check the performance by pipetting 5 ml ammonium-N standard solution into the distillation unit, add 1 drop octan-2-ol, 6 ml magnesium hydroxide suspension and steam distil the released ammonia into 5 ml boric acid solution in a 100-ml conical flask. After approximately 40 ml distillate has been collected over a 5-min period, wash the tip of the condenser into the distillate, add 2-3 drops mixed indicator solution and titrate with 0.005 M H SO until the colour changes from green to purple. A blank distillation/titra-tion is carried out using 5 ml ammonia-free water and subtracted from the standard titre to give a result which should be 5.00 ml. 

Then 75 ml of ice-cold sulfuric acid is added with rapid stirring, followed by the rapid addition of a solution of 17 gm of sodium dichromate (technical grade) in 50 ml of water. The mixture is vigorously stirred for a few minutes and is then filtered. The brown precipitate is washed with 1 liter of cold water and transferred to a steam-distillation apparatus. The product, being volatile with steam, is purified by steam distillation. The purified m-dinitrosobenzene solidifies in the distillate and is finally isolated by filtration yield 8.3 gm (51 %), m.p. 144°-145°C (this product is said to be monomeric in nature). 

C. 7-Aminotheophylline. The reaction flask of a steam distillation apparatus is charged with 19.6 g (0.069 mol) of 7-benzylideneam1notheophyll1ne and 100 mL (0.1 mol) of 1 N hydrochloric acid. The suspension is steam distilled until no more benzaldehyde is detected 1n the distillate (Note 7), The resulting clear solution in the reaction flask 1s concentrated by rotary evaporation to a volume of 30 mL, adjusted to pH 10 with concentrated ammonium hydroxide, transferred to a separatory funnel and extracted with five 60-mL portions of chloroform. The combined chloroform extracts are dried with anhydrous sodium sulfate, filtered and concentrated to dryness by rotary evaporation. The residue is recrystal 11 zed from 75 mL of water to afford 11.3 g (84%) of 7-aminotheophylline, mp 222°C.3... 

An efficient steam-distillation apparatus such as that described by Fieser 2 is recommended. A 12-1. round-bottomed flask cooled in a tub of ice serves as the receiver, which is equipped with an auxiliary vertical condenser attached to a gas absorption trap 3 to accommodate the hydrogen chloride which distils first. 

Procedure Into a suitable steam distillation apparatus (fitted with a 250 milliliter addition funnel, or better), place 100 grams (3.5 oz.) of cloves (regular store bought cloves). Thereafter, add in 500 milliliters (17 fluid oz.) of water, and then add 250 milliliters (8.4 fluid oz.) of water to the addition funnel. This 250-milliliter addition funnel should contain about 200 milliliters of water at all times, and the water therein should be added to the cloves and water mixture periodically to keep the flasks water volume at around 500 milliliters all throughout the steam distillation process. Then heat the cloves and water mixture to 105 to 110 Celsius, and allow the mixture to be steam distilled. The process should take about 150 minutes, and thereafter, stop the steam distillation process, and then recover the oily distillate in the receiver flask. Then extract this oily distillate with three 50-millilter portions (three 1.7 fluid oz. portions) of methylene chloride, and after the extraction, combine both methylene chloride portions (if not already done so). Note after each extraction, the methylene chloride will be the bottom layer each time. After the extraction, the upper water layer can be discarded. Now, extract the combined methylene chloride portion with six 50-milliliter portions (six 1.7 fluid oz. portions) of a 5% potassium hydroxide solution. After the extraction, combine all aqueous alkaline portions (if not already done so), and then briefly wash this combined aqueous alkaline portion with one portion of 50 milliliters (1.7 fluid oz.) of methylene chloride. Note after the extraction and washing, the aqueous alkaline portion will be the upper layer each time. After the extraction and washing, the methylene chloride can be recycled if desired. Then place this combined aqueous alkaline portion into a large beaker, and then carefiilly add in, slowly, 250 to 300 milliliters (8.5 to 10.1 fluid oz.) of a 5% hydrochloric solution. Note more or less acid may or 20... 

Figure Oil. Standard steam distillation apparatus. The addition funnel should be filled with water at all times.

Steam distillation apparatus (refer to any one of many laboratory texts for organic chemistry which describes the apparatus and set-up, e.g., references 1-3). 

Heat over a free flame or an electric heater until the solution has attained a clear blue color and the walls of the flask are free from carbonized material. Cautiously add 20 mL of water, cool, then add through a funnel 30 mL of a 2 5 solution of sodium hydroxide, and rinse the funnel with 10 mL of water. Connect the flask to a steam distillation apparatus, and immediately begin the distillation with steam. Collect the distillate in 15 mL of a 1 25 solution of boric acid to which has been added 3 drops of methyl red-methylene blue TS and enough water to cover the end of the condensing tube. Continue passing the steam until 80 to 100 mL of distillate has been collected, then remove the absorption flask, rinse the end of the condenser tube with a small quantity of water, and titrate with 0.01 N sulfuric acid. Each milliliter of 0.01 N acid is equivalent to 140 p.g of nitrogen. 

Most steam distillation apparatuses generate their steam internally, but some use steam provided from a steam line. 

Figure 017. Common steam distillation apparatus with steam generated internally.

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