Glycol Distearate is a chemical compound, an ester of stearic acid synthesised through the esterification of ethylene glycol and stearic acid. The simplified procedure is as follows:

The name defines the structure of the molecule:

• Glycol refers to any of a class of alcohols with two hydroxyl groups in the molecule. In this case, it refers to ethylene glycol, a simple two-carbon glycol.
• Distearate refers to the diester formed by stearic acid and an alcohol. In this case, alcohol is ethylene glycol.

Description of the raw materials used in its production:

• Stearic Acid  is a saturated fatty acid found in various vegetable and animal fats. It is a common raw material used in the production of Glycol Distearate.
• Ethylene Glycol  is a diol commonly used in various industries, including cosmetics. It plays a key role in the esterification process to form Glycol Distearate.

The synthesis process takes place in several stages:

• Preparation of starting materials. The first phase of the synthesis of Glycol Distearate concerns the preparation of raw materials. This typically involves purifying ethylene glycol and stearic acid to ensure that they are free of impurities.
• Reaction of esterification. Purified ethylene glycol and stearic acid are reacted together in the presence of a catalyst, an acid such as sulfuric acid. This process, known as esterification, causes the formation of distearate glycol. The reaction is carried out at elevated temperatures.
• Neutralization and washing. After the reaction, the mixture is neutralized, usually with an alkali such as sodium hydroxide. The product is then washed to remove unreacted reagents and by-products.
• Purification. The product is purified through processes such as filtration and distillation to remove any remaining impurities and ensure a high quality final product.
• Drying. The purified product is then dried to remove residual moisture.
• Quality control. The final product is then tested to ensure it meets the required specifications. This may involve testing for parameters such as acid value, saponification value and color.

It appears as a white powder or white flakes.

What it is used for and where

Glycol Distearate is a compound used in cosmetics and personal care products, mainly as a pearly agent in shampoos and liquid soaps to give a pearly or opalescent appearance.

Cosmetics

Glycol distearate is an alternative to the use of siloxanes in detergent products even though it cannot replace all of their characteristics. From an aesthetic point of view it gives a soft 'milk-like' appearance. It also contains a kind of wax that makes shower gels, cream soaps and shampoos shiny and smooth. 

Skin conditioning agent - Emollient. Emollients have the characteristic of enhancing the skin barrier through a source of exogenous lipids that adhere to the skin, improving barrier properties by filling gaps in intercorneocyte clusters to improve hydration while protecting against inflammation. In practice, they have the ability to create a barrier that prevents transepidermal water loss.  Emollients are described as degreasing or refreshing additives that improve the lipid content of the upper layers of the skin by preventing degreasing and drying of the skin. The problem with emollients is that many have a strong lipophilic character and are identified as occlusive ingredients; they are oily and fatty materials that remain on the skin surface and reduce transepidermal water loss. In cosmetics, emollients and moisturisers are often considered synonymous with humectants and occlusives.

Skin conditioning agent. It is the mainstay of topical skin treatment by 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.

Opacifying agent. It is useful into formulations that may be translucent or transparent to make them opaque and less permeable to light.

Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable and are used to soothe or soften the skin and emulsify, so they need a specific, stabilising ingredient. This ingredient forms a film, lowers the surface tension and makes two immiscible liquids miscible. A very important factor affecting the stability of the emulsion is the amount of the emulsifying agent. Emulsifiers have the property of reducing the oil/water or water/oil interfacial tension, improving the stability of the emulsion and also directly influencing the stability, sensory properties and surface tension of sunscreens by modulating the filmometric performance.

Viscosity control agent. It controls and adapts viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions.  

• Molecular Formula   C₃₈H₇₄O₄
• Molecular Weight   595.006 g/mol
• CAS  627-83-8
• UNII  13W7MDN21W
• EC number  211-014-3
• DSSTox   DTXSID6027260

Synonyms 

• Ethylene glycol distearate
• Ethylene distearate
• Ethylene stearate
• Stearic acid, ethylene ester
• Ethylene glycol dioctadecanoate
• Ethylene glycol, distearate
• Octadecanoic acid, 1,1'-(1,2-ethanediyl) ester
• Stearic acid, ethylene ester

References________________________________________________________________________

Huang JC, Mieziewska K, Philp N, van Veen T, Aguirre GD. Diethylene glycol distearate (DGD): a versatile embedding medium for retinal cytochemistry. J Neurosci Methods. 1993 May;47(3):227-34. doi: 10.1016/0165-0270(93)90085-6. PMID: 8271821.

Abstract. Embedment in diethylene glycol distearate (DGD) was shown to be highly desirable and versatile for retinal cytochemical studies, including in situ hybridization, immuno- and lectin cytochemistry. This method allows for preservation of fine tissue detail as well as good reaction sensitivity. It appears to be more suitable than most other methods currently used for light microscopic retinal cytochemistry.

Nickerson JA, Krockmalnic G, He DC, Penman S. Immunolocalization in three dimensions: immunogold staining of cytoskeletal and nuclear matrix proteins in resinless electron microscopy sections. Proc Natl Acad Sci U S A. 1990 Mar;87(6):2259-63. doi: 10.1073/pnas.87.6.2259. PMID: 2315318; PMCID: PMC53666.

Abstract. We describe two methods for staining resinless thin sections with antibodies and gold-conjugated second antibodies. Immunolocalization of specific proteins is a powerful tool for cell structure studies but current techniques do not develop its full potential. Immunofluorescence provides only low-resolution localization, whereas conventional thin-section electron microscopy images and immunostains only the section surface. Resinless sections of extracted cell structures offer a simple and effective means of immuno-electron microscopy. Without embedding plastic or soluble proteins, the cell cytostructure produces high-contrast, three-dimensional images. Resinless sections of detergent-extracted cells are prepared by embedding in diethylene glycol distearate, sectioning, and removing diethylene glycol distearate before microscopy. In the first method of immunostaining, extracted cells were fixed and stained with antibodies before embedment, sectioning, removal of the embedding resin, and critical point drying. In the postembedment method, the sample was embedded and sectioned, the diethylene glycol distearate was removed, and the sample was rehydrated before antibody staining. With these techniques, specific proteins were localized with high resolution throughout the entire section. Stereoscopic micrographs of resinless sections revealed the precise localization of specific cytoskeleton and nuclear matrix proteins in three dimensions with unprecedented clarity.