High boilings

The solid content of the basic solution produced through dissolving and pre-cooking is about 70-75%, its boiling point ranges from 105-107°C. 

Continuous cookers are used almost exclusively for this operation. 

The basic solution with 70-75% solid content must be concentrated to a sugar mass of 98-99% solid content. In order to achieve such sugar concentration under atmospheric pressure the cooking temperature should be 145-150°C. At this point a negative phenomenon occurs, namely part of the sugar caramelizes. In order to avoid this normally vacuum or microfilm cookers are used. The vacuum cookers operate at reduced pressure ranging from 50 to 100 millibar, therefore the cooking temperature can be between 130-135°C. 

An even distribution of the flavouring and colouring can be achieved by folding in during cooling, i. e. as the temperature of the sugar mass drops to 70-80°C over 5-10 minutes. 

In modem continuously operating closed systems the flavourings, colourings and acids are added to the sugar mass at elevated temperatures of about 130-135°C. It should be noted that cooling is more intensive than with the traditional manufacturing method. 

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The crude phthalic anhydride is heated and held at 260 C to allow some byproduct reactions to go to completion. Purification is by continuous distillation in two columns. In the first column, maleic anhydride and benzoic and toluic acids are removed overhead. In the second column, pure phthalic anhydride is removed overhead. High boiling residues are removed from the bottom of the second column. 

Karathane A trade name for 2,4-dinitro-6-( 1 -methylheptyl)phenyl crotonate, CJ8H24N2O6, a compound which has both acaricidal and fungicidal activity. It is a red-brown oil of high boiling point, insoluble in water but soluble in most organic solvents. Karathane is used for the control of powdery mildew, and is nontoxic to mammals. 

Molecular distillation is used in the separation and purification of vitamins and other natural products, and for the distillation of high-boiling synthetic organic compounds. 

Occurs in the high-boiling fraction of coal tar. Most conveniently prepared by Skraup s reaction by healing a mixture of aniline, glycerol, sulphuric acid and nitrobenzene. Used in the manufacture of dyestuffs, and pharmaceutical products. 

CieHia. Faintly yellow plate-like crystals m.p. lOPC, b.p. Occurs in the high boiling... 

Vaseline A trade name for soft paraffin. Yellow and white semi-solid, partly translucent mixtures of hydrocarbons of the paraffin series ranging from CijHji to C2oH42- Obtained from the high-boiling fractions of petroleum... 

D 1160 Method for reduced pressure distillation of high-boiling... 

Fisher, I.P. and P. Fisher (1974), Analysis of high boiling petroleum streams by high resolution mass spectrometry . Talanta, Vol. 21, p. 867. 

The dotted lines represent hydrogen bonds. The high boiling point and viscosity of the pure acid indicate strong intermolecular forces of this kind. 

In the distilling-flask remains a very small high-boiling fraction of benzoic anhydride (b.p. 366 ), formed by the dehydrating action of the thionyl chloride on the benzoic acid ... 

Finally the cup F is connected by a wider tube H to the base of the condenser C. It is essential that when the condenser C is vertical, the tube H slopes gently downwards as shown from the cup F to the condenser C. Since high-boiling solvents are rarely used in this apparatus the condenser C... 

It follows that liquids of high boiling point should not be distilled from drying agent systems which have appreciable vapour pressures. An extreme case of this action is the dehydration of oxalic acid dihydrate by distillation over toluene or over carbon tetrachloride. 

If the solvent constituting the crystallisation medium has a compara tively high boiling point, it is advisable to wash the solid with a solvent of low boiling point in order that the ultimate crystalline product may be easily dried it need hardly be added that the crystals should be insoluble or only very sparingly soluble in the volatile solvent. The new solvent must be completely miscible with the first, and should not be applied until the crystals have been washed at least once with the original solvent. 

Drying by hydrolysis. The production of extremely dry (99 -9-(- per cent.) ethyl alcohol from commercial absolute alcohol (99-f percent.) is possible by taking advantage of the fact that the hydrolysis of an ester consumes water. Thus if the absolute alcohol is treated with a little sodium in the presence of an ester of high boiling point e.g., ethyl... 

If, however, the sodium hydroxide is removed by allowing it to react with excess of an ester of high boiling point, such as ethyl succinate or ethyl phthalate, super-dry ethyl alcohol may be obtained ... 

P -f lOROH -f 5Br, — 2H3PO, -f lORBr -f 2H,0 The reaction is of general application with primary alcohols (n propyl to n hexadecyl) the yields are over 90 per cent, of the theoretical, but with secondary alcohols the yields are 50-80 per cent. in the latter case a small quantity of high boiling point by-product is also formed which can, however, be readily removed by fractional distillation. The reaction is conveniently carried out in a special all glass apparatus. 

The sulphuric acid treatment removes high-boiling impurities which are not easily separated by distillation. 

Reflux a mixture of 68 g. of anhydrous zinc chloride (e.g., sticks), 40 ml. (47 -5 g.) of concentrated hydrochloric acid and 18-5 g. (23 ml.) of sec.-butyl alcohol (b.p. 99-100°) in the apparatus of Fig. 777, 25, 1 for 2 hours. Distil oflF the crude chloride untU the temperature rises to 100°. Separate the upper layer of the distillate, wash it successively with water, 5 per cent, sodium hydroxide solution and water dry with anhydrous calcium chloride. Distil through a short column or from a Claisen flask with fractionating side arm, and collect the fraction of b.p. 67-70° some high boiling point material remains in the flask. Redistil and collect the pure cc. butyl chloride at 67-69°. The yield is 15 g. 

Allyl Bromide. Introduce into a 1-litre three-necked flask 250 g. (169 ml.) of 48 per cent, hydrobromic acid and then 75 g. (40-5 ml.) of concentrated sulphuric acid in portions, with shaking Anally add 58 g. (68 ml.) of pure allyl alcohol (Section 111,140). Fit the flask with a separatory funnel, a mechanical stirrer and an efficient condenser (preferably of the double surface type) set for downward distillation connect the flask to the condenser by a wide (6-8 mm.) bent tube. Place 75 g. (40 5 ml.) of concentrated sulphuric acid in the separatory funnel, set the stirrer in motion, and allow the acid to flow slowly into the warm solution. The allyl bromide will distil over (< 30 minutes). Wash the distillate with 5 per cent, sodium carbonate solution, followed by water, dry over anhydrous calcium chloride, and distil from a Claisen flask with a fractionating side arm or through a short column. The yield of allyl bromide, b.p. 69-72°, is 112 g. There is a small high-boiling fraction containing propylene dibromide. 

If tile high boiling residue is transferred to a small Claisen flask and distilled, some n-hexj l alcohol passes over first, followed by n-hexyl n-caproate (2 g.) at 240-250° (mainly 245°). 

The solution may be rendered homogeneous by the addition of ethyl alcohol, but the yield appears to be slightly diminished and more high boiling point material is produced. 

By distilling the acid with an inert solvent of high boiling point, such as tetrachloroethane. The water passes over with the solvent and the anhydride remains, for example ... 

Pour the reaction mixture cautiously into 400 g. of crushed ice and acidify it in the cold by the addition of a solution prepared by adding 55 ml. of concentrated sulphuric acid to 150 ml. of water and then coohng to 0°. Separate the ether layer and extract the aqueous layer twice with 50 ml. portions of ether. Dry the combined ethereal solutions over 50 g. of anhydrous potassium carbonate and distil the filtered solution thror h a Widmer column (Figs. II, 17, 1 and II, 24, 4). Collect separately the fraction boihng up to 103°, and the dimethylethynyl carbinol at 103-107° Discard the high boiling point material. Dry the fraction of low boihng point with anhydrous potassium carbonate and redistil. The total 3 ield is 75 g. 

By-products are formed in both preparations thus in the former, anthracene, and o- and p-dibenzylbenzenes are present in the fraction of high boiling point. Diphenylmethane is more conveniently obtained by the interaction of benzyl chloride and benzene in the presence of aluminium amalgam ... 

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