Phenyl iso-thiocyanate

Pheiiyl iso-thiocyanate may be prepared in quantity directly from aniline. Aniline, carbon disulphide and concentrated aqueous ammonia react to form the sparingly soluble ammonium phenyldithiocarbamate this is decomposed by lead nitrate to produce phenyl iso-thiocyanate ... 

Step 2. Extraction of the basic components. Extract the ethereal solution (Ej) with 15 ml. portions of 5 per cent, hydrochloric acid until all the basic components have been removed two or three portions of acid are usually sufficient. Preserve the residual ethereal solution (E2) for the separation of the neutral components. Wa.sh the combined acid extracts with 15-20 ml. of ether discard the ether extract as in Step 1. Make the acid extract alkaline with 10-20 per cent, sodium hydroxide solution if any basic component separates, extract it with ether, evaporate the ether, and characterise the residue. If a water-soluble base is also present, it may be recognised by its characteristic ammoniacal odour it may be isolated from the solution remaining after the separation of the insoluble base by ether extraction by distilling the aqueous solution as long as the distillate is alkahne to htmus. Identify the base with the aid of phenyl iso-thiocyanate (compare Section 111,123) or by other means. 

A major advance was devised by Pehr Edman (University of Lund Sweden) that has become the standard method for N terminal residue analysis The Edman degrada tion IS based on the chemistry shown m Figure 27 12 A peptide reacts with phenyl iso thiocyanate to give a phenylthwcarbamoyl (PTC) denvative as shown m the first step This PTC derivative is then treated with an acid m an anhydrous medium (Edman used mtromethane saturated with hydrogen chloride) to cleave the amide bond between the N terminal ammo acid and the remainder of the peptide No other peptide bonds are cleaved m this step as amide bond hydrolysis requires water When the PTC derivative IS treated with acid m an anhydrous medium the sulfur atom of the C=S unit acts as... 

In a 1 litre round-bottomed flask provided with an efficient double surface condenser, place 40 g. (39 ml.) of aniline, 50 g. (40 ml.) of carbon sulphide (CAUTION inflammable) (1), and 50 g. (63-5 ml.) of absolute ethyl alcohol (2). Set up the apparatus in the fume cupboard or attach an absorption device to the top of the condenser (see Fig. II, 8, 1) to absorb the hydrogen sulphide which is evolved. Heat upon an electrically-heated water bath or upon a steam bath for 8 hours or until the contents of the flask solidify. When the reaction is complete, arrange the condenser for downward distillation (Fig. II, 13, 3), and remove the excess of carbon disulphide and alcohol (CAUTION inflammable there must be no flame near the receiver). Shake the residue in the flask with excess of dilute hydrochloric acid (1 10) to remove any aniline present, filter at the pump, wash with water, and drain well. Dry in the steam oven. The yield of crude product, which is quite satisfactory for the preparation of phenyl iso-thiocyanate (Section IV,95), is 40-45 g. Recrystallise the crude thiocarbanilide by dissolving it, under reflux, in boiling rectified spirit (filter through a hot water funnel if the solution is not clear), and add hot water until the solution just becomes cloudy and allow to cool. Pure sym.diphenylthiourea separates in colourless needles, m.p. 154°. 

Upon heating thiocarbanilide with concentrated hydrochloric acid, it is partly converted into phenyl iso-thiocyanate ... 

Phenyl iso-thiocyanate, 642,643 Phenylthioureas, 422, 655 Phenylurea, 644, 645 Phenylurethanos, 264 Phloroacetophenone, 727, 736 Phosgene, 185 Phosphoric acid, 189, 284 Phosphorus, detection of, 1043 Phosphorus, red, purification of, 193 Phosphorus oxychloride, 367 Phosphorus pentabromide, 489, 492 Phosphorus pentachloride, 799, 822, 974 Phosphorus pentoxide, handling of, 407 Phosphorus tribromide, 189, 492 Phosphorus trichloride, 367 Phosphorus trisulphide," 836 Phthalamide, 983 Phthalein test, 681 ... 

Thus, by bromolactonization of 3-hexenoic and 3-octenoic acids, /1-lactones 4 have been prepared that afford 2-oxazolidinones 5 (R - Et, Bu) as single stereoisomers in 97 % and 98 % yield, respectively. If diphenylcarbodiimide is used, the 2-oxazolidinimine 6 is obtained in 95 % yield. On the other hand, reaction with phenyl iso thiocyanate gives rise to the l,3-oxathiolan-2-imine 7 in 56% yield while treatment with carbon dioxide affords the corresponding carbonate 8 in about 40 % yield. H3CO... 

Phase-transfer catalysts, 220, 221,305-306 Phenanthrenes, 319, 320 9-Phenanthrol, 431 Phenol annelation, 272 Phenoxysulfonyl azide, 377-378 Phenylacetaldehyde, 217 Phenylacetylene, 7 2 (S)-3-Phenyl-1-butene, 36 Phenyl chlorothionocarbonate, 306-307 Phenyl cyanate, 307-308 Phenyldiazomethane, 308 o-Phenylene phosphorochloridate, 91-92 o-Phenylglydne methyl ester, 308 Phenyl isocyanate, 309 Phenyl isocyanide, 309-310 Phenyl iso thiocyanate, 122 Phenyllithium, 5... 

A peptide composed of 12 amino acids does not react with dabsyl chloride or with phenyl iso thiocyanate. Cleavage with cyanogen bromide yields a peptide "with a carboxyl-terminal homoserine lactone residue, which is readily hydrolyzed, in turn yielding a peptide whose sequence is determined by the Edman procedure to be... 

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