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Chemistry

Mannitol in Chemistry Structure Properties and Uses

Mannitol in Chemistry Structure Properties and Uses

Q: 2. What is the chemical formula and molar mass of mannitol?

**The chemical formula of mannitol is C6H14O6, and its molar mass is approximately 182.17 g·mol-1.** The molar mass is calculated as:6 × 12.01 (C) = 72.0614 × 1.008 (H) = 14.116 × 16.00 (O) = 96.00Total ≈ 182.17 g·mol-1This value is important for stoichiometric calculations and solution preparation.

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What Is Mannitol Structure Formula Preparation Reactions and Applications

Alcohols are saturated organic compounds that contain at least one hydroxyl group (OH). The general formula of alcohol is CnH2n+1OH. Alcohol can be of many types. In this article, we will discuss the mannitol. This article will cover all important points like what is mannitol, mannitol structure, mannitol uses, mannitol action and mannitol injection uses.

What is Mannitol?

Mannitol is a six-carbon, linear, simple, and polyhydroxy sugar alcohol. It is a low molecular weight compound. Its chemical formula is C6H14O6. It gets easily filtered through the glomerulus but it can not be reabsorbed in the renal tubule of the kidney.

Mannitol Structure

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Mannitol is an isomer of sorbitol. The only difference in the structure of mannitol from sorbitol is the orientation of the hydroxyl group on the second carbon. All the carbons present in the mannitol are sp3 hybridized. All bonds present in the mannitol are sigma bonds.

Comparison of Sorbitol and Mannitol.

Sorbitol	Mannitol
Hydroxyl group at second carbon is present out of the plane.	Hydroxyl group at second carbon is present behind the plane.
Less sweet than sugar.	Sweeter than sugar.
Contains 2.6 calories/gram.	Contains 1.6 calories/gram.
Mainly used as a sugar substitute.	Mainly used as a medicine.

Properties of Mannitol

The molar mass of mannitol is 182.172 g/mol.
The density of mannitol is 1.489 at 68°F.
The boiling point of mannitol is 563°F at 3.5 mm Hg.
The melting point of mannitol is 333°F.
It is an odourless compound.
It occurs naturally in white crystalline or in granule form.
It is sweet in taste.

Mannitol Action

Mannitol is a polyhydroxy compound, which is mildly metabolized by the body. The renal tubule does not have the capacity to absorb it. Therefore, it rapidly gets excreted by the kidney, when mannitol injection is used and poorly absorbed when taken orally.
Mannitol, when ingested orally, passes through the intestine and excreted in the feces as the small intestine is not able to absorb it properly. Therefore, it does not affect blood sugar and can be used as a sweetener for the diabetic patient.

Mannitol Uses

Mannitol is used for promoting diuresis for acute renal failure.
Mannitol is used for increased intracranial pressure.
Mannitol is used for the excretion of toxic material.
Mannitol is used as a sweetener for diabetic food products.
Mannitol is used for preventing intradialytic hypotension.
It is used to measure Extracellular Fluid (ECF) and Glomerular Filtration Rate (GFR).
It is used in cardiopulmonary bypass.

Mannitol Injection Uses

Mannitol is used as a medicine. Mannitol infused into a vein or into the urethra. It should never be given subcutaneously. It is infused by health care professionals in a hospital or clinic. The total concentration, dosage, and rate of mannitol administration should be governed by the nature and severity of the condition. The standard adult dose ranges from 50-200 g/day. The rate of infusion is usually adjusted to maintain a urine flow.

Harmful Effects of Mannitol

It can cause dehydration when consumed in excess amounts.
At low temperature, it gets precipitated and can damage the vascular organ system.
It can cause heart failure.
It can cause pulmonary edema.
It can cause renal failure.

Did You Know?

Mannitol is found in mushrooms, brown algae, and bark of manna trees.
Mannitol lowers the blood pressure.
Mannitol in the intestine for a long time can cause bloating and diarrhoea.

FAQs on Mannitol in Chemistry Structure Properties and Uses

1. What is mannitol in chemistry?

**Mannitol is a six-carbon sugar alcohol (polyol) with the molecular formula C₆H₁₄O₆.** It is derived from the reduction of the monosaccharide mannose and contains six hydroxyl (–OH) groups.

Classified as a hexitol (six-carbon polyhydric alcohol).
Systematic IUPAC name: (2R,3R,4R,5R)-hexane-1,2,3,4,5,6-hexol.
Widely used in food, pharmaceuticals, and laboratory chemistry.

2. What is the chemical formula and molar mass of mannitol?

**The chemical formula of mannitol is C₆H₁₄O₆, and its molar mass is approximately 182.17 g·mol^-1.** The molar mass is calculated as:

6 × 12.01 (C) = 72.06
14 × 1.008 (H) = 14.11
6 × 16.00 (O) = 96.00
Total ≈ 182.17 g·mol^-1

This value is important for stoichiometric calculations and solution preparation.

3. What type of compound is mannitol?

**Mannitol is a polyhydric alcohol (polyol), specifically a hexitol.** It contains six hydroxyl (–OH) functional groups attached to a saturated carbon chain.

Functional group: Alcohol (–OH)
No carbonyl group (unlike sugars such as glucose).
Belongs to the class of sugar alcohols formed by reduction of monosaccharides.

This structure makes mannitol highly soluble in water and capable of hydrogen bonding.

4. How is mannitol prepared or synthesized?

**Mannitol is prepared by catalytic hydrogenation of mannose or fructose.** The carbonyl group (–CHO or >C=O) is reduced to an alcohol group (–OH).

Example reaction (hydrogenation of mannose):

C₆H₁₂O₆(aq) + H₂(g) → C₆H₁₄O₆(aq)

Typically carried out using a nickel (Ni) catalyst.
The aldehyde group is converted into a primary alcohol group.

This reduction reaction is a common method for producing sugar alcohols in industry.

5. What are the physical properties of mannitol?

**Mannitol is a white, crystalline, water-soluble solid with a sweet taste.** Its physical properties arise from extensive hydrogen bonding.

Appearance: White crystalline powder
Melting point: Approximately 165–168°C
Highly soluble in water
Low hygroscopicity compared to other sugar alcohols

The multiple –OH groups allow strong intermolecular hydrogen bonding, increasing its melting point and solubility.

6. What is the difference between mannitol and sorbitol?

**Mannitol and sorbitol are structural isomers with the same formula C₆H₁₄O₆ but different stereochemistry.** The difference lies in the spatial arrangement of hydroxyl groups.

Mannitol is derived mainly from mannose.
Sorbitol is derived mainly from glucose.
They differ in configuration at one chiral carbon atom.

Although they share the same molecular formula, their stereochemical differences lead to variations in sweetness and physical properties.

7. Why is mannitol considered a sugar alcohol?

**Mannitol is called a sugar alcohol because it is formed by reducing a sugar’s carbonyl group to an alcohol group.** In this process, the aldehyde or ketone group is converted to an additional –OH group.

Starting sugar: Mannose (C₆H₁₂O₆)
Reduction adds hydrogen, forming C₆H₁₄O₆
Contains only alcohol functional groups (no C=O group).

This chemical transformation classifies mannitol as a polyol rather than a true carbohydrate.

8. Is mannitol a reducing sugar?

**Mannitol is not a reducing sugar because it lacks a free aldehyde or ketone group.** Reducing sugars must contain a carbonyl group capable of oxidation.

Mannitol contains only –OH (alcohol) groups.
It does not react with Tollens’ reagent or Fehling’s solution.
It cannot reduce Ag⁺ or Cu²⁺ ions.

The absence of a carbonyl group prevents it from acting as a reducing agent.

9. What are the chemical reactions of mannitol?

**Mannitol undergoes typical alcohol reactions such as esterification and oxidation.** Its six hydroxyl groups determine its chemical behavior.

Esterification: Reacts with acids to form esters.
Oxidation: Strong oxidizing agents can convert –OH groups into carbonyl or carboxyl groups.
Dehydration: Under acidic conditions, it may undergo dehydration reactions.

Because it lacks a carbonyl group, it does not show reactions characteristic of aldehydes or ketones.

10. What are the uses of mannitol in chemistry and industry?

**Mannitol is used as a pharmaceutical excipient, osmotic diuretic, and low-calorie sweetener due to its chemical stability and solubility.** Its multiple hydroxyl groups make it chemically stable and non-reactive under normal conditions.

Used in tablets as a diluent and stabilizer.
Acts as an osmotic diuretic in medicine.
Used as a low-calorie sweetener in food chemistry.
Serves as a reference compound in analytical chemistry.

Its polyol structure makes it safe, non-reducing, and suitable for diverse industrial applications.