D-Mannitol Usage and Synthesis

D-Mannitol Usage and Synthesis

Introduction: 

D-Mannitol, also known as D-mannitol, is a hexavalent alcohol widely distributed in plants or plant secretions. It can be extracted from kelp or seaweed; it can also be obtained by catalytic hydrogenation of glucose or sucrose.

Source: 

Natural products are widely found in leaves, stems, roots, etc. of plants. For example, the white powder on the surface of seaweed and dried persimmons is mannitol. It is also found in high concentrations in edible fungi, lichens, onions, and carrots. The mannan obtained from the sap (secretions, dried) of Fraxinus ornus, a plant of the Oleaceae family, contains 30% to 50% mannitol.

Chemical properties: 

D-mannitol, colorless to white needle-shaped or rhombic columnar crystals or crystalline powder. Odorless, with a refreshing sweet taste. Sweetness is about 57% to 72% of sucrose. Each gram produces 8.37J of heat, about half of glucose. Contains a small amount of sorbitol. Relative density 1.49. Optical rotation [α] D20-0.40° (10% aqueous solution). Hygroscopicity Chemicalbook is extremely small. Aqueous solution is stable. Stable to dilute acid and dilute alkali. Not oxidized by oxygen in the air. Soluble in water (5.6g/100ml, 20℃) and glycerol (5.5g/100m1). Slightly soluble in ethanol (1.2g/100m1). Soluble in hot ethanol. Almost insoluble in most other commonly used organic solvents. The pH value of 20% aqueous solution is 5.5 to 6.5.

Uses: 

D-mannitol is a good diuretic in medicine, which can reduce intracranial pressure, intraocular pressure, and treat kidney medicine, dehydration agent, sugar substitute, and is also used as an excipient for tablets and a diluent for solids and liquids. Mannitol injection, as a high-osmotic antihypertensive drug, is a commonly used drug for clinical rescue, especially for brain diseases. It has the characteristics of fast blood pressure reduction and accurate efficacy required by drugs for reducing intracranial pressure. As an excipient for tablets, mannitol is non-hygroscopic, dries quickly, has good chemical stability, and has the characteristics of refreshing taste and good granulation. It is used in most tablets such as anticancer drugs, antibacterial drugs, antihistamines, and vitamins. In addition, it is also used in chewable tablets such as hangover medicines and mouth fresheners.

In terms of food, D-mannitol has the lowest water absorption among sugars and sugar alcohols, and has a refreshing sweet taste. It is used for anti-sticking of foods such as maltose, chewing gum, and rice cakes, and as anti-sticking powder for general cakes. It can also be used as a low-calorie, low-sugar sweetener for foods for diabetics and bodybuilding foods. In industry, mannitol can be used in the plastics industry to make rosin chemicalbook acid esters and artificial glycerol resins, explosives, detonators (nitrated mannitol), etc. It is used for the determination of boron in chemical analysis and as a bacterial culture agent in biological testing. Although mannitol can be absorbed by the human gastrointestinal tract, it does not accumulate in the body. After being absorbed, part of it is metabolized in the body, and the other part is excreted from the urine; dibromomannitol can be obtained by reacting with hydrobromic acid.

Identification and determination of boron and germanium, biochemical research, polarographic analysis of boron, metal masking agent, standard for determination of hydroxyl groups in organic microanalysis, renal function test, haploid breeding. In microbiology: mannitol is a good culture medium for some microorganisms.

Production method: 

50% sucrose aqueous solution is hydrogenated under nickel catalysis, about a quarter of it is converted into mannitol, and the rest is converted into sorbitol, which is then crystallized, separated and refined. It can also be obtained by soaking kelp after iodine extraction, adding alkali to neutralize, and then electrodialysis, concentration, crystallization, separation and refinement.

Mannitol can be extracted from kelp or seaweed, but it is usually extracted by electrolytic reduction or catalytic reduction of glucose or sucrose solution.

It is obtained by reducing a 50% aqueous solution of sucrose with hydrogen (pressure 4.9-14.7 MPa, 120-150°C) in the presence of a nickel catalyst, of which 1/4 is converted into mannitol and 3/4 is converted into sorbitol, which is then crystallized, separated and refined.