1,3-butanediol (1,3-Butylene Glycol) is an organic alcohol, an organic chemical of the C4 platform, butanediol glycol. It is a compound of butanediol with two hydroxy groups in positions 1 and 3 derived from a butane hydride.

The name describes the structure of the molecule

• Butylene - Indicates a carbon chain with four atoms.
• Glycol - Denotes the presence of two alcohol (–OH) groups in the molecule.

Description of raw materials used in production

• Crude oil - Butylene glycol is often derived from crude oil through cracking processes and subsequent chemical reactions.

Synthesis process

• Petroleum cracking - To obtain lighter fractions like propene.
• Hydration of propene - This process involves adding water to propene to form propanol.
• Conversion of propanol to butanediol - Through reaction and distillation processes, propanol can be converted into 1,3-butylene glycol.

It appears as a viscous, odourless liquid with a slightly bitter taste or as a fine white or yellowish powder. Highly soluble in water..

What it is used for and where

Cosmetics

• Humectant. Hygroscopic compound used to minimise water loss in the skin and to prevent it from drying out by facilitating faster and greater absorption of water into the stratum corneum of the epidermis.  The epidermis is the most superficial of the three layers that make up human skin (epidermis, dermis and hypodermis) and is the layer that maintains hydration in all three layers. In turn, the epidermis is composed of five layers: horny, the most superficial, granular, spinous, shiny, and basal. Humectants have the ability to retain the water they attract from the air in the stratum corneum and have the function of moisturising the skin. They are best used before emollients, which are oil-based.
• Fragrance. It plays a decisive and important role in the formulation of cosmetic products as it provides the possibility of enhancing, masking or adding fragrance to the final product, increasing its marketability. It is able to create a perceptible pleasant odour, masking a bad smell. The consumer always expects to find a pleasant or distinctive scent in a cosmetic product. 
• Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.
• Solvent. It is the substance for dissolving or dispersing surfactants, oils, dyes, flavourings, bactericidal preservatives in solution.In fact, it dissolves other components present in a cosmetic formulation. Solvents are generally liquid (aqueous and non-aqueous).
• Viscosity control agent. It controls and adapts, Increasing or decreasing, viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions. 

Food

Flavouring agent.  Antibacterial agent for cheese, meat, etc.

Medical

Intermediate chemical compound.

Other uses

• Used in polyester plasticisers, raw material and co-monomer of unsaturated polyester resin, in polyurethane resins. Industrial dehydrating agent. Moisturizer and softener for textiles, tobacco and paper. Chemical intermediate in dyes.

1,3-Butylene Glycol safety 

Typical optimal commercial product characteristics 1,3-Butylene Glycol

• Molecular Formula: C₄H₁₀O₂
• Linear Formula CH₃CH(OH)CH₂CH₂OH
• Molecular Weight: 90.122 g/mol
• Exact Mass    90.068077
• CAS: 107-88-0  18826-95-4  6290-03-5  817176-75-3 
• UNII  3XUS85K0RA
• EC Number: 203-529-7  228-532-0
• PubChem Substance ID 57648493
• DSSTox Substance ID  DTXSID8026773
• IUPAC  butane-1,3-diol
• InChI=1S/C4H10O2/c1-4(6)2-3-5/h4-6H,2-3H2,1H3
• InChl Key      PUPZLCDOIYMWBV-UHFFFAOYSA-N
• SMILES    CC(CCO)O
• MDL number MFCD00004554
• Beilstein Registry Number 1731276 
• ICSC    1182
• NSC   402145    6966
• RTECS   EK0440000

Synonyms: 

• (±)-1,3-Butanediol
• 1,3-Dihydroxybutane
• Methyltrimethylene glycol
• 1,3-Butandiol
• 1-Methyl-1,3-propanediol
• beta-Butylene glycol
• 1,3 Butylene glycol
• 1,3-BUTANEDIOL
• Butane-1,3-diol
• 1,3-Butylenglykol
• (RS)-1,3-Butandiol
• 1,3-Butanodiol
• (+/-)-1,3-Butanediol
• Caswell No. 128GG
• 1,3-Butylene glycol
• 1,3-Butanediol, (R)-
• 1,3-Butanediol, (S)-
• S-(+)-1,3-Butanediol
• (R)-(-)-1,3-Butylene Glycol
• Aliphatic diol
• b-Butylene glycol

Butylene Glycol is a controversial component: on the one hand, the ecobias do not like it, on the other there is no study that does not completely recommend it.

The reported cases of allergy are quite rare (1) and the product is commonly used as it is considered low irritation.

Unfortunately, allergies can also be caused by these products.

References________________________________

(1) Case of allergic contact dermatitis due to 1,3-butylene glycol.
Aizawa A, Ito A, Masui Y, Ito M.
J Dermatol. 2014 Sep;41(9):815-6. doi: 10.1111/1346-8138.12603.