Anti-bumping

The action of this and other anti-bumping devices e.g., minute carborundum chips) is dependent upon the fact that the transformation of a superheated liquid into the vapour will take place immediately if a vapour phase e.g., any inert gas) is introduced. The effect may be compared with that produced by the introduction of a small quantity of a solid phaM into a supercooled liquid, e.g., of ice into supercooled water. 

Consumables - filter papers, anti-bumping granules, Soxhlet thimbles and column packings for chromatography. 

Surgical and examination gloves, inhalation masks, overshoes, protective sheeting and tailored covers, mattress and bedding covers, anti-bump protection bars. .. 

R,5)-lbuprofen acid (20 g, 96.9 mmol), p-toluenesulfonic acid (0.44 g, 2.27 mmol) and 2-ethoxyethanol (21.9 mL, 224 mmol) were dissolved in the organic solvent, isooctane (180 mL). The boiling chips were added into the reaction flask as anti-bumping agent. Then the reaction mixtures were refluxed for 8—9 h using a Dean-Stark apparatus. 

Refluxing is a technique that allows substances to be heated for a prolonged period of time without the volatile reactants and/or products escaping into the atmosphere. The hydrolysis mixture is placed in a round-bottomed flask, along with some anti-bumping granules. 

When a reaction mixture is heated, there is a tendency for it to boil violently as large bubbles of superheated vapour suddenly erupt from the mixture. This is prevented by the addition of the anti-bumping granules. A condenser is placed in the mouth of the flask and connected to a cold-water tap (water goes in at the bottom and out at the top). The flask is then heated and the vapours produced are condensed back into liquids when they reach the cool condenser. 

Never use diazomethane with ground glass joints or glass apparatus with rough, broken edges and do not use anti bumping chips. 

When the glassware has cooled, increase the inert gas flow, quickly disconnect the distillation flask, add any drying agent required, a few anti-bumping granules and the liquid to be distilled, then reassemble the system. 

Before you start heating a liquid or solution you must always take one of the following anti-bumping precautions ... 

Add one or two boiling stones or anti-bumping granules these can be filtered olf later in the process. 

Make sure that you add the anti-bumping device before you start heating since uncontrolled boiling may occur immediately. You must allow the liquid to cool back to room temperature and then add the anti-bumping device. 

Insoluble material anti-bumping granules, pieces of filter paper, traces of drying agents, grit, hair and other materials which may have been present in the starting chemicals. 

Add cold water (about 100 mL) and a glass rod as an anti-bumping device to the flask and then heat the mixture on a hot plate until the compound has dissolved completely. Then add more water (about 10 mL), to ensure that precipitation of the solute does not occur during the following stages. 

This is a modification of gravity filtration (p. 28), designed to remove solvent-insoluble impurities, charcoal, anti-bumping granules or magnetic fleas from the hot solution before cooling the solution to form the crystals of purified product. 

The transformation of n-butane over Ga-H-ZSM-5, Zn-H-ZSM-5 and H-ZSM-5 catalysts was carried out in a continuous-flow quartz reactor with 0.5 g of catalyst at atmospheric pressure. Inert silica grains and anti bumping granules were placed at both ends of the catalyst bed. The reactor was heated in an electric oven and the temperature of the catalyst bed was... 

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