Difference between revisions of "Glycerol"

Latest revision as of 14:50, 18 November 2023

Glycerol

Names
IUPAC name Propane-1,2,3-triol
Preferred IUPAC name Propane-1,2,3-triol
Other names 1,2,3-Propanetriol 1,2,3-Trihydroxypropane Glycerin Glycerine Glycyl alcohol Propanetriol
Properties
Chemical formula	C3H8O3
Molar mass	92.09 g/mol
Appearance	Colorless viscous liquid
Odor	Odorless
Density	1.261 g/cm3
Melting point	17.8 °C (64.0 °F; 290.9 K)
Boiling point	290 °C (554 °F; 563 K)
Solubility in water	Miscible
Solubility	Miscible with ethanol, methanol, propylene glycol Insoluble in acetone, benzene, carbon disulfide, CCl4, chloroform, diethyl ether, petroleum ether, THF, vegetable oils
Vapor pressure	0.003 mmHg (50°C)
Hazards
Safety data sheet	Sigma-Aldrich
Flash point	160 °C (320 °F; 433 K) (closed cup) 176 °C (349 °F; 449 K) (open cup)
Related compounds
Related compounds	Ethylene glycol Propylene glycol Erythritol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Glycerol, alternatively spelled glycerin, or glycerine, is a simple sugar alcohol sometimes used as a solvent. It is a polyol, consisting of a propane molecule with one hydrogen on each of the carbons being substituted by a hydroxyl group.

Glycerol is sometimes used as a laboratory solvent, though this is made difficult by its high viscosity. It is also used in the manufacture of the well-known explosive nitroglycerin.

Properties

Chemical

Glycerol has several niche uses in home chemistry. A mixture of glycerol and oxalic acid can be distilled to produce formic acid. This reaction occurs in several steps, at temperatures above 100 °C.

When glycerin is heated to 280 °C, it decomposes into acrolein:

(CH₂OH)₂CHOH → CH₂=CHCHO + 2 H₂O

Perhaps most famously, it can be nitrated using sulfuric and nitric acids in an ice bath to produce nitroglycerin, a sensitive liquid high explosive used to make dynamite.

It can also be used as an inert solvent for producing extracts from plants or carrying out organic reactions.

Physical

Glycerol is a colorless, viscous, and odorless liquid at room temperature with a mild sweet taste similar to artificial sweeteners. It is soluble in water, but has limited solubility in most organic solvents such as acetone, chloroform, and diethyl ether. It is hygroscopic.

Availability

Glycerol can be found in many pharmacies and grocery stores where it is used as "skin protectant". As with many medical and health products, it is sold at a very high markup, which means that buying glycerol online from certain wholesalers is actually much cheaper.

Preparation

Glycerol is produced by the hydrolysis, or saponification, of plant and animal fats using a strong base, such as sodium hydroxide. It is usually simpler to purchase it rather than go through the process of purifying the product from this reaction, though.

Projects

• Make formic acid
• Make nitroglycerin
• Make allyl alcohol
• Make acrolein
• Antifreeze
• Make copper-polyol complex^[1]

Handling

Safety

Glycerol is more-or-less nontoxic, as it is an important biological chemical. Food-grade glycerol can be tasted for those that are curious, though external medicinal grades cannot be guaranteed safe for consumption (Sciencemadness user Ave369 used medical grade glycerol to soften homemade vodka, and nothing bad happened to her).

Storage

Glycerol should be stored in sealed bottles, as it is hygroscopic and it is extremely difficult to remove the water.

Disposal

Glycerol poses little toxicity to the environment and can be safely poured down the drain.

References

1. ↑ https://www.youtube.com/watch?v=EKj3Oa5GTcM

Relevant Sciencemadness threads

• Drying Glycerol
• Valorizing the Glycerol from Biodiesel Production