Ethylhexyl palmitate or 2-Ethylhexyl palmitate is a chemical compound, an ester that is obtained by synthesis resulting from the reaction of 2-ethylhexyl alcohol with palmitic acid.

The name defines the structure of the molecule:

• Ethylhexyl refers to a specific chain derived from the combination of hexyl (a six-carbon chain) and ethyl (a two-carbon chain).
• Palmitate refers to the form of ester or salt of palmitic acid, a type of saturated fatty acid commonly found in both animals and plants, especially palm oil.

The synthesis process takes place in several stages:

• Preparation. The process begins with the preparation of acid and alcohol. Palmitic acid is a common fatty acid found in fats and waxes, and 2-ethylhexanol is a fatty alcohol. Both are commercially available and are prepared for reaction.
• Esterification. Palmitic acid and 2-ethylhexanol are inserted into a reaction vessel. An acid catalyst, often sulfuric acid, is added to the mixture which, when heated, starts the esterification reaction. This reaction causes the formation of Ethylhexyl Palmitatee water.
• Separation. The reaction mixture is allowed to cool. Ethylhexyl Palmitate, being less polar than water, will separate. Water and all non-reacted materials can be removed.
• Purification. Ethylhexyl Palmitate is purified by distillation, heated and the vapors are collected and condensed. This process helps to remove any remaining impurities.
• Quality control. The final product is tested to ensure it meets the specifications required for use in cosmetics and personal care products. This includes checking its purity, color and smell.

It appears as an odourless, colourless liquid or as a white, poorly hydrolysable, hardly oxidisable powder.

What it is used for and where

Raw material for cosmetics

Cosmetics

It is a dry, yet breathable oil with the ability to penetrate and moisturise the skin, and is thermally stable.

It is used in cosmetics in creams, skin care products, foundations, skin care oils, mascaras, hair oils, lipsticks and in other body care products as an emollient, emulsifier. It provides a smooth and soft skin feel without greasiness with good permeability and is non-sticky. It is a good substitute for mineral oil and is compatible with other emollients.

It also has a moisturising, softening, dispersing function. It has good biodegradability and preservation.

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.

Fragrance. It plays a very important role in the formulation of cosmetic products as it allows perfume to be enhanced, masked or added to the final product, improving its commercial viability.  The consumer always expects to find a pleasant scent in a cosmetic product.

Applications

• Skin Conditioning Agent - Helps keep the skin soft and moisturized, reducing dryness.
• Solvent - Can be used as a solvent for active ingredients or colorants in cosmetic formulations.
• Oil Substitute - Sometimes used as a lightweight, non-greasy alternative to oils in various products.
• Perfume Base - Its volatility makes it suitable as a base in perfumes.

Studies:

2-Ethylhexyl palmitate was prepared in organic solvents catalysed by an immobilised lipase QLM. Microwave irradiation was used to enhance the activity of the enzyme and shorten the reaction time. Microwave reaction conditions were optimised. Compared to the free QLM under classical heating, the immobilised QLM under microwave oven showed higher enzyme activity and the conversion could reach 99% in about 3.0 hours. Furthermore, the immobilised QLM showed excellent reusability under microwave irradiation (1).

This work reports on the application of a lipase in the esterification of 2-Ethylhexyl palmitate in a solvent-free system with an immobilised lipase (Lipozyme RM IM). A sequential strategy was used by applying two experimental designs to optimise the production of 2-ethylhexyl palmitate. An empirical model was then constructed to evaluate the effects of process variables on reaction conversion. Subsequently, the operating conditions that optimise the production of 2-ethylhexyl palmitate were established as an acid/alcohol molar ratio of 1: 3, temperature of 70 degrees C, stirring speed of 150 rpm, 10% by weight of enzyme, leading to a reaction conversion of 95%. From this point, a kinetic study was conducted to evaluate the effect of the acid: alcohol molar ratio, enzyme concentration and temperature on product conversion. The results obtained at this stage show that an excess of alcohol (molar ratio of acid to alcohol of 1: 6), relatively low enzyme concentration (10% by weight) and a temperature of 70 degrees C lead to conversions close to 100% (2).

For more information:

Ethylhexyl palmitate studies

• Molecular Formula   C₂₄H₄₈O₂ 
• Molecular Weight   368.64
• Exact Mass    368.36500
• CAS   29806-73-3
• UNII    2865993309
• EC Number   249-862-1
• DSSTox Substance ID  
• IUPAC  octan-3-yl hexadecanoate
• InChI=1S/C24H48O2/c1-4-7-9-10-11-12-13-14-15-16-17-18-20-22-24(25)26-23(6-3)21-19-8-5-2/h23H,4-22H2,1-3H3
• InChl Key      GJQLBGWSDGMZKM-UHFFFAOYSA-N
• SMILES   CCCCCCCCCCCCCCCC(=O)OC(CC)CCCCC
• MDL number  MFCD00072255
• PubChem Substance ID    
• RTECS   RT4740000

Synonyms

• Palmitic acid, 2-ethylhexyl ester
• Palmitic acid 2-ethylhexyl ester
• 2-Ethylhexyl palmitate
• Hexadecanoic acid, 2-ethylhexyl ester
• 2-Ethylhexyl hexadecanoate
• Wickenol 155

References_____________________________________________________________________

(1) Wang L, Zhang Y, Zhang Y, Zheng L, Huang H, Wang Z. Synthesis of 2-Ethylhexyl Palmitate Catalyzed by Enzyme Under Microwave. Appl Biochem Biotechnol. 2018 May;185(1):347-356. doi: 10.1007/s12010-017-2666-2. 

(2) Richetti A, Leite SG, Antunes OA, de Souza AL, Lerin LA, Dallago RM, Paroul N, Di Luccio M, Oliveira JV, Treichel H, de Oliveira D. Optimization of 2-ethylhexyl palmitate production using lipozyme RM IM as catalyst in a solvent-free system. Appl Biochem Biotechnol. 2010 Apr;160(8):2498-508. doi: 10.1007/s12010-009-8756-z.