# Phenylacetic acid from styrene, sulfur and ammonia



## shelom (Feb 20, 2022)

Autoclave volume 3L made from stainless steel tube 100mm diameter and wall thickness 5mm with MMA welding. Threaded tubes 1\2 welded to it. DO NOT USE COOPER AND ALUMINIUM ALLOYS FOR THIS SYNTESIS
Into autoclave put 500ml styrene 1100ml 25% ammonia 450 gr sulfur. After filling autoclave closed with wrench PTFE lent was used. Autoclave placed on water bath 95C at 5 days with break at night. Every 1-3 hours autoclave stirred by hands.

After 5 days at water bath autoclave was opened. Lower organic brown layer separated and washed with water. Autoclave washed with detergent.

In 1.3 liters of water dissolved 350 gr sodium hydroxide. Sodium hydroxide solution and autoclave tar placed to the stainless steel boiler with 1 meter 2/3 tube(reflux) and boiled 2 days with break at night.

After boiling in mixture added 300ml xylene and upper organic layer was separated. In water layer added 2 liters 15% hydrochloric acid

DANGER!!!Lots of hydrogen sulfide evaporated its jets are visible. In room all cooper things was turned black.
Hydrogen sulfide evaporate if you add acid at soduim phenylacetate solution because it contains sodium sulfide. Also hydrogen sulfide stands of if you evaporate ammonium polysulphide solution for recovery sulfur

If you make reaction at low temperatures(100C) pressure is low about 5-10bar. But main reaction product thioamide. If you make reaction at high temperature(150-180C) pressure high(20bar) and main reaction product amide phenylacetic acid

After filtration and washing 190gr wet impure phenylacetic acid was prepared. If after filtration acid water solution was extracted and saturated sodium chloride(50-100 gr liter) with toluene can be obtained about 10-20gr phenylacetic acid. Phenylacetic acid contaminated sulfur and needs in separation with ethanol as example.

Willgerodt reaction with styrene and ammonia gives low phenylacetic acid yield(Not more 30-35%)

Warning! Autoclave tar has a very unpleasant odor in very low concentration which is very persistent

Notes:
Carbon steel can de used as autoclave material(fire extinguisher or tube as example. YOU MUST NOT USE BRASS OR ALUMINIUM PLUG ). In first experiment i used carbon steel tube from old plumbing 1/1/2 with inner diameter 40mm and 3mm wall thickness. But it slowly corrodes. Also desirable add sodium carbonate to water bath to prevent corrosion
Autoclave tar(organic layer) contains some free sulfur. To get rid of it you can keep it several days.
Autoclave tar contains many organosulfur compound(diphenyl thiopnene and thiophane main) and tars. After extraction phenylacetic acid about 1/2 tar is not dissolve in water alkali
350gr alkali is much. 200gr enough
Adding ethanol in reaction mixture may increase yield, but part phenylacetic acid amide gone into water layer ammonium polysulfide and its necessary evaporate(ammonia and hydrogen sulfide released) and wash from sulfur with ethanol.
Ammonium polysulfide solution can be used again if add half sulfur and 1/4 ammonia. Or it can be evaporate to recovery sulfur. I recovered about 100-150 gr sulfur from 450-500 gr initial.
If you want prepare P2P from this acid by pyrolysis with acetate you MUST clear phenylacetic acid from sulfur. Sulfur reacts with phenelacetic acid at high temperatures. Very much hydrogen sulfide formed(brass fittings turned black)

Styrene can be obtained from polystyrene pyrolysis. 1 kg polystyrene gives about 500ml styrene. Best source polystyrene is compact disc container or other TRANSPARENT polystyrene or EPS( It can be smelted with torch or heat gun in steel container).TV, printer monitor cases org printer cartridge from HIPS can be used. HIPS under pyrolysis gives many ethylbenzene and cumene which difficult separate from styrene. Do not use polystyrene marked as PS-FR(17)! It giver hydrogen bromide and bromoorganic compound if pyrolysed.


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