Show the reaction, calculate the 5 yield (by dimensional analysis) and report th
ID: 674524 • Letter: S
Question
Show the reaction, calculate the 5 yield (by dimensional analysis) and report the melting point of diphenylacetylene. What would be the product if only 1 mole of KOH was used per mole of 1.2-dibromo-1,2-diphenylethane? Show the balanced reaction. (Not the mechanism) What is the purpose of ethylene glycol in this experiment? Why isn't methanol used instead? Construct a flow chart on the production and isolation of diphenylacetylene, starting from 1, 2 dibromo-1,2-diphenylethane, KOH and ethylene glycol. What is removed when using water to rinse off crude crystals after vacuum filtration? Use your flowchart to help answer this question. What would be the major product when 1 mole of 1-bromocyclohexane is reacted with 1 mole of KOH in ethylene glycol? Show the mechanism, and name the product.Explanation / Answer
From this you can prepare a flow chart by understanding how it is done :
The crystalline product is isolated by filtration. The technique for doing this varies depending on the scale on which the crystallization was performed. The solid product is isolated by vacuum filtration using a Büchner or Hirsch funnel and a clean, dry filter flask. The crystals normally are washed with a small amount of pure, cold solvent, with the vacuum off; the vacuum is then reapplied to remove as much solvent as possible from the filter cake. Care must be taken in this step to ensure that the filter paper is not lifted off the bed of the filter while the vacuum is off; this could result in loss of product when the vacuum is reapplied to remove the washes. Further cooling of the filtrate, sometimes called the mother liquor, in an ice-water or ice salt bath may allow isolation of a second crop of crystals. The filtrate can also be concentrated by evaporating part of the solvent and cooling the residual solution. The crystals isolated as a second or even a third crop are likely to be less pure than those in the first. Consequently, the various crops should not be combined until their purity has been assessed by comparison of their melting points.
Isolation and Drying. Collect the crystals on a Büchner or Hirsch funnel by vacuum filtration and wash the filter cake with two small portions of cold water. Press the crystals as dry as possible on the funnel with a clean cork or spatula. Spread the benzoic acid on a watch-glass, protecting it from airborne contaminants with a piece of filter paper, and air-dry it at room temperature or in an oven. Be certain that the temperature of the oven is below the melting point of the product
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