Boiling capillary

When the hydrolysis is complete carefully wash out the condenser with 10-12 c.c. of water. Then distil up to 5 c.c. of liquid into a small conical quartz flask. Use the condenser in the downward position and if necessary add a few boiling capillaries to the liquid in the flask. Repeat the distillation three more times, each time adding 7 c.c. of water. Test the distillate (volume about 20 c.c.) with some barium chloride for sulphuric acid (none should be present), boil for seven to eight seconds and titrate at once with 0-033 N sodium hydroxide solution 1 from a micro-burette having 0-02 c.c. scale-divisions. Use phenolphthalein as indicator and continue the titration until the colour becomes just pink and remains so for a few seconds. For the second titration distil 2 x 7 or 3 x 7 c.c. and for the third and fourth titrations only about 7 c.c. on each occasion. 

Apparatus for simple distillation in vacuum assembled from standard components a = three-neck round-bottomed flask NS 29 with 2 side tubes NS 14.5 h = thermometer with ground joint NS 14.5 c = boiling capillary d = still head with ground joints NS 29 and 14.5 e = Dimroth condenser ... 

The adapters 10 and 17 can be employed in cases where the distillate is not separated into fractions. Sketch 11 shows a receiver with which three fractions may be collected, while version 12 can take 7 fractions. If it is necessary to use a boiling capillary, the Claisen still head (Fig. 236) may be chosen, or else a three-necked flask with a capillary 18 inserted into one of the ground joints. 

DIN 12404/63 boiling capillary with standard ground joint... 

S = still pot heating and control, 4—9a = distillation apparatus with heating jacket, still pot, Claisen still head, adapter and receiver, 10, II = bubble counters with boiling capillary, 12a, IS = manometers with inclined tube, 17,19 = photo-cells, 14—16 — recorder with thermostat and amplifier, 20 = pressure controller... 

A 600-ml. glass flask is equipped with a ground glass joint with a boiling capillary a and a ground glass thermometer b. An efficient condenser is attached at 0 and terminates in a receiver. The apparatus is connected to an aspirator via a safety trap. The... 

A 33% solution of ZnS204 (1300 g.) is added to 600 g. of a 30% formaldehyde solution the addition is accompanied by a temperature rise to 50°C. The liquid is stirred and the temperature maintained at 60-65 °C for some time. The mixture is filtered and set aside for 2-3 days. The clear solution is again filtered and concentrated in vacuum while SO 3 is aspirated in through a boiling capillary. The zinc formaldehydesulfoxylate is the first to precipitate. The crystals are separated from the mother liquor by centrifugation and dried by heating in vacuum. 

HaargefaC capillary air bleed/ boiling capillary/ air leak tube dist Siedekapillare capillary blotting Diffusionsblotting capillary breaking/ capillary fracture (fibers) Kapillarbruch... 

Beckmann thermometer A very sensitive mercury thermometer with a small temperature range which can be changed by transferring mercury between the capillary and a bulb reservoir. Used for accurate temperature measurements in the determination of molecular weights by freezing point depression or boiling point elevation. 

The resolution of capillary columns enables the separation of all principal components of a straight-run gasoline. The most frequently used stationary phases are silicone-based, giving an order of hydrocarbon elution times close to the order of increasing boiling point. 

Determination of Boiling-points. The following alternative methods are recommended, (a) Draw one drop of the liquid into a capillary tube so that the drop is about i cm. from one end. 

The chief disadvantages of the latter are (i) the necessity for boiling the mercury to remove the air from the closed reference tube when filling the gauge, (ii) the tendency for air to enter the closed limb after a period of time, and (iii) the difficulty of precision reading due to the capillary action in the... 

An elementary account of the subject has been given in the previous Section. For the fractional distillation under diminished pressure of liquids diflfering only slightly in boiling point, a firactionating column (see Sections 11,15 and 11,17) must be used. Provision must, of course, be made for the insertion of a capillary tube into the fiask containing the mixture. This can be done by any of the following methods —... 

Boil 2 g. of the ester with 30 ml. of 10 per cent, sodium or potassium hydroxide solution under reflux for at least 1 hour. If the alcohol formed is water (or alkali) soluble, the completion of the hydrolysis will be indicated by the disappearance of the ester layer. Distil ofiF the liquid through the same condenser and collect the first 3-5 ml. of distillate. If a distinct la3 er separates on standing (or upon saturation of half the distillate with potassium carbonate), remove this layer with a capillary dropper, dry it with a little anhydrous potassium carbonate or anhydrous calcium sulphate, and determine the b.p. by the SiwoloboflF method... 

In a 1 litre round-bottomed flask, equipped with an air condenser, place a mixture of 44 g. of o-chlorobenzoic acid (Section IV,157) (1), 156 g. (153 ml.) of redistilled aniline, 41 g. of anhydrous potassium carbonate and 1 g. of cupric oxide. Reflux the mixture in an oil bath for 2 hours. Allow to cool. Remove the excess of aniline by steam distillation and add 20 g. of decolourising carbon to the brown residual solution. Boil the mixture for 15 minutes, and filter at the pump. Add the filtrate with stirring to a mixture of 30 ml. of concentrated hydrochloric acid and 60 ml. of water, and allow to cool. Filter off the precipitated acid with suction, and dry to constant weight upon filter paper in the air. The yield of iV-phenylanthranilic acid, m.p. 181-182° (capillary tube placed in preheated bath at 170°), is 50 g. This acid is pure enough for most purposes. It may be recrystaUised as follows dissolve 5 g. of the acid in either 25 ml. of alcohol or in 10 ml. of acetic acid, and add 5 ml. of hot water m.p. 182-183°. 

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