Abstract:
This experiment aims to prepare glucosazone from glucose by reacting it with phenylhydrazine hydrochloride in the presence of sodium acetate buffer.
Introduction:
Glucosazone is a derivative of glucose formed by the reaction between glucose and phenylhydrazine hydrochloride under acidic conditions. It is commonly used in carbohydrate chemistry to identify and characterize sugars. The formation of glucosazone involves the condensation of one mole of glucose with two moles of phenylhydrazine to form a hydrazone.
Experimental Details:
Materials:
- Glucose
- Phenylhydrazine hydrochloride
- Sodium acetate buffer
- Distilled water
- Ice bath
- Test tubes
- Test tube holder
- Bunsen burner
- Hot plate
Procedure:
- Prepare a sodium acetate buffer solution by dissolving sodium acetate in distilled water. Adjust the pH to around 5-6.
- Add a small amount of glucose to a test tube.
- Add an equal volume of phenylhydrazine hydrochloride solution to the test tube.
- Place the test tube in a water bath at 60-70°C for about 10-15 minutes.
- Allow the solution to cool to room temperature and then place it in an ice bath to facilitate crystallization.
- Collect the crystals formed by filtration.
- Wash the crystals with cold distilled water and dry them.
- Weigh the obtained crystals to determine the yield.
Observations and Calculations:
The reaction between glucose and phenylhydrazine hydrochloride can be represented as follows:
\[ \text{Glucose} + 2\text{Phenylhydrazine hydrochloride} \rightarrow \text{Glucosazone} + 2\text{HCl} + 2\text{H}_2\text{O} \]
The yield of glucosazone can be calculated using the following formula:
\[ \text{Yield} (\%) = \frac{{\text{Mass of glucosazone obtained}}}{{\text{Mass of glucose used}}} \times 100\% \]
Conclusion:
In this experiment, glucosazone was successfully prepared from glucose by reacting it with phenylhydrazine hydrochloride in the presence of sodium acetate buffer. The obtained crystals were identified as glucosazone based on their characteristic properties.
Precautions:
- Handle phenylhydrazine hydrochloride with care as it is toxic.
- Ensure proper ventilation in the laboratory as phenylhydrazine hydrochloride can release toxic fumes.
- Use appropriate personal protective equipment, such as gloves and goggles, when handling chemicals.
- Dispose of chemical waste according to laboratory safety guidelines.
Short Questions:
- What is the purpose of preparing glucosazone?
- Which reagent is used in the preparation of glucosazone?
- Under what conditions is glucosazone formed?
- What is the chemical equation for the formation of glucosazone?
- How is the yield of glucosazone calculated?
- What is the role of sodium acetate buffer in the reaction?
- What are the characteristic properties of glucosazone crystals?
- What precautions should be taken while handling phenylhydrazine hydrochloride?
- Why is it necessary to cool the reaction mixture in an ice bath?
- How can the purity of the obtained glucosazone crystals be determined?
- What is the color of glucosazone crystals?
- What is the importance of drying the glucosazone crystals?
- How does the pH of the reaction mixture affect the formation of glucosazone?
- Why is it important to wash the obtained crystals with cold distilled water?
- What is the significance of filtering the reaction mixture?
- What safety precautions should be followed during the experiment?
- What other carbohydrates can be converted into azones?
- What are the applications of glucosazone?
- How does the reaction temperature influence the yield of glucosazone?
Answer: Glucosazone is prepared for the identification and characterization of sugars.
Answer: Phenylhydrazine hydrochloride is used as the reagent.
Answer: Glucosazone is formed under acidic conditions.
Answer: The chemical equation is: Glucose + 2 Phenylhydrazine hydrochloride → Glucosazone + 2 HCl + 2 H2O.
Answer: The yield is calculated as the mass of glucosazone obtained divided by the mass of glucose used, multiplied by 100%.
Answer: Sodium acetate buffer provides acidic conditions required for the formation of glucosazone.
Answer: Glucosazone crystals are yellow and have a characteristic melting point.
Answer: Phenylhydrazine hydrochloride is toxic, so proper safety measures such as wearing gloves and goggles should be followed.
Answer: Cooling facilitates crystallization of glucosazone, leading to better yields.
Answer: Purity can be determined through melting point analysis or spectroscopic techniques.
Answer: Glucosazone crystals are typically yellow.
Answer: Drying removes any remaining solvent and ensures accurate weighing of the crystals.
Answer: An acidic pH is necessary for the formation of glucosazone.
Answer: Washing removes impurities and residual reagents from the crystals.
Answer: Filtration separates the solid glucosazone crystals from the liquid reaction mixture.
Answer: Safety precautions include wearing protective clothing, working in a well-ventilated area, and handling chemicals with care.
Answer: Other carbohydrates such as fructose and galactose can also be converted into azones.
Answer: Glucosazone is used in carbohydrate chemistry for the identification and characterization of sugars.
Answer: Higher temperatures can lead to increased reaction rates but may also result in side reactions or decomposition, affecting the yield of glucosazone.
Multiple Choice Questions (MCQs)
- What is the purpose of glucosazone preparation?
a) To identify sugars
b) To produce glucose
c) To test for starch
d) To measure pH
Answer: a) To identify sugars - Which reagent is used in the preparation of glucosazone?
a) Sodium hydroxide
b) Phenylhydrazine hydrochloride
c) Acetic acid
d) Ethanol
Answer: b) Phenylhydrazine hydrochloride - At what temperature is the reaction mixture heated?
a) Room temperature
b) 100°C
c) 60-70°C
d) 0°C
Answer: c) 60-70°C - What is the role of sodium acetate buffer in the reaction?
a) To neutralize the reaction mixture
b) To provide acidic conditions
c) To prevent side reactions
d) To increase the reaction rate
Answer: b) To provide acidic conditions - How is the yield of glucosazone calculated?
a) Using a pH meter
b) By measuring volume change
c) By weighing the crystals
d) By titration
Answer: c) By weighing the crystals