How does the Dean-Stark trap work?

Overview. A Dean-Stark trap is a special piece of glassware, which allows the collection of water during a reaction through an azeotropic distillation. The desire to collect water from a reaction can have various reasons. It can drive the equilibria in reactions, where water is formed as a byproduct.

What is the principle of the Dean-Stark apparatus and how does this method work?

The interactive lab primer – Dean-Stark apparatus The reaction is carried out under reflux in a solvent which is less dense than water to form an azeotrope. The apparatus allows the water to be separated from the condensed azeotrope preventing it from returning to the reaction mixture.

How do you distill an azeotrope?

To obtain the pure material one must “break the azeotrope”, which involves a separation method that does not rely on distillation. A common approach involves the use of molecular sieves. Treatment of 96% ethanol with molecular sieves gives anhydrous alcohol, the sieves having adsorbed water from the mixture.

How do you remove water from azeotrope?

The water can be removed through a stopcock in the bottom of the Dean-Stark trap (see Figure 4.29). Table 4.6. Different azeotropes formed by the most common solvents.

Why is toluene used in Dean Stark apparatus?

A common example is the removal of water generated during a reaction in boiling toluene. An azeotropic mixture of toluene and water distills out of the reaction, but only the toluene (density 0.865 g/ml) returns, since it floats on top of the water (density 0.998 g/ml), which collects in the trap.

What is meant by azeotropic distillation?

Definition: A method of separating mixtures based on differences in their volatilities in a boiling liquid mixture.

Which method is used for separation of azeotropic mixture?

Azeotropic distillation (AD) is a process to break azeotrope where another volatile component, called the entrainer, the solvent, or the mass separating agent (MSA), is added to form a new lower-boiling azeotrope that is heterogeneous.

How do you separate azeotropes?

Azeotropes can be separated by distillation (azeotropic distillation, extractive distillation, pressure swing distillation). In the case of azeotropic distillation a solvent is added which forms a lower boiling azeotrope (e.g. separation of aliphatics-aromatics using acetone.

How azeotropes can be eliminated?

The addition of a material separation agent, such as benzene to an ethanol/water mixture, changes the molecular interactions and eliminates the azeotrope.

How do you remove water from toluene?

Moisture is removed from the sample by distillation as an azeotrope with toluene. The water is collected in a suitable trap and its volume is measured at a known temperature. This method is applicable to all unmodified starches, most modified starches and many starch products (Note 1).