Question

Describe a chemical procedure to separate a mixture of benzyl alcohol and o-cresol and to recover each in pure form.

Short answer

Answer: The key difference between benzyl alcohol and o-cresol is their functional groups and boiling points. Benzyl alcohol has a hydroxyl group and a boiling point of 205°C, while o-cresol has a phenolic hydroxyl group and a boiling point of 191°C. This difference in boiling points can be used to separate them by utilizing a simple distillation technique.

Step-by-step solution

Understand the properties of benzyl alcohol and o-cresol

Benzyl alcohol and o-cresol are organic compounds with different chemical structures and properties. Benzyl alcohol is an aromatic alcohol with the formula C6H5CH2OH, while o-cresol is an aromatic phenol with the formula C6H4(OH)(CH3). The key difference between the two compounds is the functional group - a hydroxyl group in benzyl alcohol and a phenolic hydroxyl group in o-cresol. As a result, benzyl alcohol has a boiling point of 205°C, and o-cresol has a boiling point of 191°C. This difference will allow us to separate them using distillation techniques.

Set up a distillation apparatus

In order to separate the benzyl alcohol and o-cresol mixture, a simple distillation setup can be used. Prepare a round-bottom flask with the appropriate volume and connect it to a condenser with a receiving flask to collect the distilled compounds. Before starting the distillation process, make sure that all connections are made properly, and water is running through the condenser to ensure efficient cooling of the vapor.

Perform the distillation process

Add the mixture of benzyl alcohol and o-cresol to the round-bottom flask and gently heat the flask using a heating mantle or a water bath. As the temperature of the mixture increases, the compound with the lower boiling point, o-cresol, will start to evaporate and travel through the condenser where it will cool down and condense back into a liquid. Ensure that the heating temperature is controlled to avoid overlapping boiling points, which would make the separation less effective. Collect the distilled o-cresol in the receiving flask. Once the first distillation is complete, you should have o-cresol in your receiving flask and the benzyl alcohol left in the round-bottom flask.

Separate the remaining benzyl alcohol

After obtaining the o-cresol, the remaining compound in your round-bottom flask should be fairly pure benzyl alcohol. At this point, the two compounds have been separated; however, to obtain them in the purest form possible, perform a second distillation (fractional distillation) of each compound. This will ensure that any remaining impurities are removed.

Collect and store the purified compounds

As each compound has been separated and purified, transfer them to appropriate containers and label them accordingly. Store the purified benzyl alcohol and o-cresol in a cool, dry place away from direct sunlight or heat sources to ensure their stability and purity be maintained. By following these steps, you can successfully separate a mixture of benzyl alcohol and o-cresol into their pure forms by taking advantage of their different boiling points and utilizing a simple distillation technique.

Key concepts

Benzyl Alcohol

Benzyl alcohol is a type of aromatic alcohol with the chemical formula C6H5CH2OH. It is a colorless liquid with a mild, pleasant aromatic scent, making it notable for its various applications in perfumery and cosmetics. It features a structure where a hydroxyl group (-OH) is connected to a benzyl group, a specific kind of aromatic ring containing a CH2 group. This structure endows it with a higher boiling point than some other alcohols, reaching 205°C.

Benzyl alcohol is used in multiple industries. In addition to being a fragrance additive, it serves as a solvent and an ingredient in pharmaceutical products. Due to its lower toxicity compared to other alcohol analogs, it is often chosen as a safer alternative for organic synthesis and extraction processes. Its solubility in water is moderate, allowing it to blend well in various formulations, while its ability to dissolve a wide range of nanoparticles makes it valuable in paint and ink industries as well.

o-Cresol

o-Cresol, or ortho-cresol, is known as an aromatic phenol with the molecular formula C6H4(OH)(CH3). It is one variety of cresols, where the hydroxyl group is ortho-positioned relative to the methyl group on the aromatic benzene ring. This structure gives it phenolic properties, differentiating it from other alcohols like benzyl alcohol. One of its prominent characteristics is its boiling point, which is 191°C, lower than that of benzyl alcohol.

In terms of applications, o-cresol is utilized in the creation of synthetic resins, disinfectants, and as an intermediate in chemical manufacturing. It has antiseptic properties, sometimes used in limited applications, although care is needed due to its higher toxicity compared to benzyl alcohol. Its ability to react with formaldehyde forms products used in resin production, like those in laminated and coated surfaces.

Boiling Point Separation

Boiling point separation is a crucial concept in the distillation process, allowing the separation of different components in a mixture based on their boiling points. When you heat a mixture, the component with the lower boiling point will evaporate first. This is because it requires less energy to overcome the intermolecular forces keeping it in liquid form.

In our case of separating benzyl alcohol and o-cresol, the principle of boiling point separation is employed. o-Cresol boils at 191°C, so it will vaporize and be collected first in a distillation apparatus. Benzyl alcohol, with its higher boiling point of 205°C, remains in the liquid phase until the temperature is raised further. This clear difference in boiling points is what allows these two components to be effectively separated through controlled heating and collection processes.

Distillation Apparatus

A distillation apparatus is a setup used to separate mixtures based on differences in their boiling points through evaporation and condensation. Key components generally involve:

• A boiling flask, often round-bottomed, where the mixture is heated.
• A condenser, which cools down the vapor to form liquid.
• A receiving flask, where the distilled liquid is collected.

Properly assembling the components is essential for effective separation. Water flow through the condenser ensures the vapor cools predictably. In this setup, you can conduct both simple and fractional distillation. Simple distillation is adequate when boiling points of substances differ significantly, as seen with benzyl alcohol and o-cresol.

While performing distillation, careful heating is vital to avoid co-boiling or overlapping phase transitions. Using a heating control apparatus such as a mantle allows for precise temperature adjustments, ensuring each compound's optimal separation. This meticulous process helps ensure purity in the recovered compounds, reflecting advancements in chemical engineering and laboratory practices.