How to distinguish between cyclohexane and cyclohexanol

In the field of chemical industry, cyclohexane and cyclohexanol are two substances that are often confused. Because they are similar in many properties, it is very important to distinguish them for synthesis reaction and experimental operation. This article from the structure, physical properties, chemical properties and identification methods, detailed analysis of how to distinguish between cyclohexane and cyclohexanol.

1. molecular structure and basic properties

1. molecular structure Cyclohexane and cyclohexanol are cyclic compounds with the molecular formulas C6H12 and C6H12O, respectively. Six carbon atoms in the cyclohexane molecule form a saturated ring structure without double bonds or triple bonds, while cyclohexanol has an additional hydroxyl group (-OH) in the ring, making the molecule unsaturated bonds (C-O single bonds). This structural difference makes the physical and chemical properties of cyclohexane and cyclohexanol significantly different.

2. state and boiling point Cyclohexane is a liquid under standard conditions with a boiling point of 55.3°C; cyclohexanol is also a liquid but has a slightly higher boiling point of about 166.5°C. The structure of cyclohexane is stable, and the intermolecular force is small, so the boiling point is low; because of the hydroxyl group, the intermolecular hydrogen bond of cyclohexanol is strong, which leads to the increase of boiling point.

2. physical properties and identification methods

1. Density and Appearance Cyclohexane is a colorless liquid at room temperature with a density of about 0.81g/cm3; cyclohexanol is also a colorless liquid, but the density is slightly higher, about 0.81g/cm3 (the specific value varies with purity). Although the two are similar in density, they can be distinguished by distillation or densitometer measurements.

2. surface tension The surface tension of cyclohexane is large, about 0.34 N/m; the surface tension of cyclohexanol is small, about 0.22 N/m. If the test is carried out with a surface tension measuring instrument, the two can be visually distinguished.

3. Acid-base and chemical reaction Cyclohexane itself has no obvious acidity and basicity, but it may show weak acidity under some specific reaction conditions. Cyclohexanol has weak alkalinity and is easy to neutralize with acidic solution. This property can be identified in the laboratory by reaction with acids or bases.

4. Reaction with water Cyclohexane is immiscible with water and will stratify in cold water to form two layers of static liquid; cyclohexanol is easily soluble in water and will form a homogeneous system in water. This phenomenon can be identified by a simple experiment: put the two into water separately and observe the stratification.

3. chemical properties and applications

1. chemical reaction characteristics Cyclohexane is relatively stable in chemical reactions, but epoxidation reaction may occur under specific catalyst and high temperature conditions to generate cyclohexene and other products; cyclohexanol has stronger oxidation and is easy to react with a variety of reagents, such as reacting with acid anhydride to generate esters, or reacting with metal sodium to generate ethane.

2. Industrial Applications Cyclohexane is commonly used in organic synthesis, especially as a monomer for some polymer materials, such as the manufacture of polypropylene; cyclohexanol is widely used in pharmaceutical, fine chemical synthesis and other fields, especially in the structure of the need for alcohol hydroxyl.

4. identification method summary

1. distillation method Cyclohexane and cyclohexanol have different boiling points in the distillation process, and the two can be separated by distillation experiments to observe the difference in distillation curves.

2. density measurement method By measuring the density of two substances, they can be distinguished by their similar density differences, usually with the help of densitometers or precision instruments.

3. Mixing experiment with water The liquids to be tested were mixed with water separately and observed for miscibility or stratification. Cyclohexane will stratify, while cyclohexanol will be homogeneous with water.

4. Acid and alkaline test Through the reaction with acid or alkali, the acid-base properties of the substance to be tested can be preliminarily judged, so as to further distinguish.

5. surface tension test Using a surface tension meter, the difference in surface tension values of cyclohexane and cyclohexanol was observed, thereby performing the discrimination.

5. practical application considerations

In practice, differentiating cyclohexane from cyclohexanol requires a combination of multiple identification methods to improve accuracy. For example, in organic synthesis, if it is desired to introduce hydroxyl groups, cyclohexanol is usually chosen as the starting material because of its pronounced basicity; where a saturated cyclic structure is desired, cyclohexane is more suitable.

Understanding the physical and chemical properties of cyclohexane and cyclohexanol can help to better control the reaction conditions in the experiment and avoid unnecessary interference and errors.

Through the above analysis, we can clearly see that there are significant differences between cyclohexane and cyclocyclohexanol in molecular structure, physical properties, and chemical reactions. Mastering these identification methods not only helps to improve the accuracy of experimental operations, but also provides a scientific basis for application in industrial production.