1, 2-propylene glycol and 1, 3-propylene glycol in cosmetics

In the daily use of cosmetics ingredient list, often see propylene glycol this substance. Some labels are 1, 2-propylene glycol, others are 1, 3-propylene glycol, so what’s the difference between the two?

1, 2-propylene glycol, CAS number 57-55-6, molecular formula C3H8O2. It is a chemical reagent, miscible with water, ethanol and various organic solvents. Normally, it is a colorless viscous liquid, almost odorless, and slightly sweet.

It can be used as a wetting agent in combination with glycerin or sorbitol in cosmetics, toothpaste and soap. It is used in hair dye as a moisture conditioner, hair levelling agent, and also as an antifreeze.

1, 3-propylene glycol, CAS 504-63-2, molecular formula C3H8O2. Colorless, odorless, salty, hygroscopic viscous liquid, can be oxidized, esterification reaction, can be miscible with water, can be miscible in ethanol, ether.

It can be used for the synthesis of many drugs, new polyester PTT, pharmaceutical intermediates and new antioxidants. It is a raw material for the production of unsaturated polyesters, plasticizers, surfactants, emulsifiers and demulsifiers.

They have the same molecular formula and belong to isomers.

In high concentrations in cosmetics, 1, 2-propylene glycol can be used as an antimicrobial or osmotic agent.

If the concentration is slightly lower, it is generally used as a moisturizer or cleaning aid,

At lower concentrations, it can be used as a pro-solvent for the active ingredient,

At different concentrations, the irritation and safety of the skin are completely different.

1, 3-propylene glycol is mainly used as a solvent in cosmetics, as a moisturizing solvent for organic polyols, which helps cosmetic ingredients penetrate into the skin.

It has higher moisture retention than glycerin, 1,2 propylene glycol and 1,3 butanediol. No viscosity, no burning sensation, no sensitive irritation problems.

Also acts as a viscosity control agent.

The main production methods of 1,2 propylene glycol are: 1, propylene oxide water method. 2, propylene direct catalytic oxidation method. 3. Transesterification. 4, glycerol hydrolytic synthesis method.

The main production methods of 1, 3-propylene glycol are: 1, acrolein water method. 2, ethylene oxide method. 3, glycerol hydrolytic synthesis method. 4. Microbial method.

The propylene glycol sold on the general market is mainly based on 1, 2-propylene glycol without special requirements, because the price difference between the two is large. 1, 3-propanediol is about eight times more expensive than 1, 2-propanediol. The production method of 1, 3-propylene glycol is slightly complicated, the yield is low, and the relative price has been high.

Data show that 1, 3-propylene glycol has lower irritation, burning and other discomfort reactions than 1, 2-propylene glycol, and even reaches the level of no discomfort reaction.

Component description:

1, 2-propylene glycol is derived from propylene oxide from petrochemical sources and is a small molecular moisturizing component. It is a kind of polyol, almost colorless, odorless, non-greasy, and can be completely dissolved in water, and also has anti-corrosion effect. Propylene glycol can also be used as a slippery agent, which is highly permeable and enhances the skin’s absorption of other ingredients, but acts as a moisturizer

The proportion of water grabbing is not high. In general cosmetics, the proportion of propylene glycol added will not exceed 5%, and the skin of a few people will have a tingling and burning sensation after use. The US FDA believes that propylene glycol is a cosmetic ingredient that can be safely used, but it is better to avoid the use of this ingredient for sensitive skin

Healthy skin does not have to worry too much.

1, 3-propylene glycol is an important chemical raw material, usually derived from corn sugar, known as “corn propylene glycol” in the industry, the ingredient is safe and mild, used in cosmetics as moisturizer, thickener and solvent, will not cause irritation and discomfort to the skin.