Pages

Thursday, June 28, 2018

SYNTHESIS OF HEPTANE



STEP 1: Place 100 g (1.53 mol) of zinc wool in a 1-litre three-necked flask and amal­gamate it. 

STEP 2: Fit the flask with a sealed stirrer unit, an efficient double surface condenser and a lead-in tube dipping almost to the bottom of the flask for the introduction of hydro­gen chloride gas; insert an empty wash bottle between the hydrogen chloride generator and the flask. 

STEP 3: Introduce through the condenser 250 ml of concentrated hydrochloric acid and 50 ml of water, set the stirrer in motion and then add 40 g (0.35 mol) of heptan-4-one

STEP 4: Pass a slow current of hydrogen chloride through the mixture; if the reaction becomes too vigorous, the passage of hydrogen chloride is tempor­arily stopped. 

STEP 5: After 2-3 hours most of the amalgamated zinc will have reacted. 

STEP 6: Leave the reaction mixture overnight, but disconnect the hydrogen chloride gas supply first. 

STEP 7: Remove the stirrer and the condenser from the flask. Arrange for direct steam distillation from the flask by fitting a stopper into one neck, a knee tube connected to a downward condenser in the central aperture and connect the lead-in tube to a source of steam. 

STEP 8: Stop the steam distillation when the distillate passes over as a clear liquid. Separate the upper layer, wash it twice with distilled water, dry with magnesium sulphate or anhydrous calcium sulphate and distil through a short fractionating column. 

STEP 9: Collect the fraction, b.p. 97-99 °C (1). The yield of heptane is 26 g (74%).

Notes to keep in mind:


1. The products of most Clemmensen reductions contain small amounts of unsaturated hydrocarbons. These can be removed by repeated shaking with 10 per cent of the volume of concentrated sulphuric acid until the acid is colourless or nearly so; each shaking should be of about 5 minutes duration. The hydrocarbon is washed with water, 10 per cent sodium carbonate solution, water (twice), dried with magne­sium sulphate or anhydrous calcium sulphate and finally fractionally distilled over sodium.

No comments:

Post a Comment

We specialize in producing high value chemicals. Besides our regular products, we strive to develop new products based on customer’s requirements. Our R&D center plays crucial role in handling complex chemistries and developing newer technologies. We respect intellectual property rights and have confidentiality agreement with various multi national companies. We undertake contract manufacturing of fine chemicals and advance intermediates of API’s.