SUSTAINABILITY
The science of bio-based alkanes in cosmetics
Antoine Piccirilli - VG Chem Consulting, France Didier Lanquetin - Enviro-Stratégies, France
ABSTRACT
In recent years, bio-based alkanes obtained from vegetable oils or sugar, respectively by processes of conventional chemistry and by synthetic biology implemented from genetically modified microorganisms, have appeared on the market. An examination of the production yields and the results of lifecycle analyses highlight the great superiority of conventional chemistry compared to synthetic biology, which ultimately proves to be of low productivity and high environmental impact, far from being in phase with the societal and environmental requirements of the cosmetics industry.
Alkanes of fossil origin have been used in cosmetic products for many years. Indeed, many skin care, hair care or even make-up products contain isododecane, isohexadecane and purified petroleum cuts (e.g. Isopar isoparaffins).1 These petrochemical alkanes are multi- functional compounds with interesting physical and sensory properties: emollient, moisturizing properties, non-greasy and silky feel, excellent skin tolerance, great chemical stability.2
In
addition, their price is extremely competitive. However, they also have their drawbacks.
They are derived from non-renewable fossil raw materials, generating greenhouse gases as they are obtained by hydrocracking petroleum. On the other hand, they are far from being totally biodegradable, leading to pollution of water, air and soil. Some of these alkanes also have a synthetic hydrocarbon odour that must be masked in cosmetic formulations by using masking and odorant substances, which make the formulations more complex and can lead to skin tolerance problems. Last but not least, their cosmetic INCI
names, directly accessible on the packaging of the finished product, evokes the industrial chemistry of synthesis (ex. C13-C15 Alkane, Isododecane). This is why today’s consumers, increasingly aware in real time thanks to applications available on their cell phones, spot these substances and turn away from the act of purchasing. Hydrocarbons like silicones, parabens and petrolatum no longer have a good press and are increasingly being replaced by bio-based alkanes.
www.personalcaremagazine.com In the last ten years, alkanes made from bio-
based raw materials have been introduced to the market. Among them, two distinct categories can be distinguished: i) alkanes obtained from vegetable oils (palm, coconut) by conventional chemical processes and ii) those resulting from synthetic biology obtained from sugar (glucose from sugar cane and beet in particular).
Biobased alkanes from vegetable oils There are two types of bio-based alkanes derived from vegetable oils: those that are identical in molecular structure to certain petrochemical alkanes and those that have no fossil counterpart, such as squalane, a substance that is not present in the plant kingdom but is strongly inspired by it.
Linear bio-based alkanes Linear bio-based alkanes have identical chemical structures to their petrochemical
counterparts. These compounds generally have carbon chain lengths between C12 and C22. These alkanes differ in technical performance, production process and plant origin. Biobased dodecane/tetradecane is obtained
from coconut oil fatty alcohol (marketed under the brand name Vegelight 1214, INCI name: Coconut Alkanes).3
process is an alcoholysis of coconut oil leading to methyl esters, which are transformed into coconut fatty alcohols by catalytic hydrogenolysis (Figure 1, reaction 1). A fractional distillation step then isolates
the lauric (C12) and myristic (C14) alcohols. This alcohol is then dehydrated to alpha-olefins in the presence of an acidic solid catalyst. The obtained alkene is finally hydrogenated to coconut alkanes. The process leads to two reusable co-
products: coconut glycerine and methanol which is recycled in the alcoholysis reaction. Concerning the compliance with the key principles of green chemistry, this process mainly uses heterogeneous catalysts easily separable from the reaction medium, which avoids neutralization and washing operations generating waste to be treated. Similarly, the atom economy, a key
criterion of green chemistry which consists in maximizing the number of atoms of raw material and reactants transformed into the target product (dodecane/tetradecane), is higher than 85% (Table 1). The undecane/tridecane blend - marketed
as Cetiol Ultimate, INCI name: Undecane and Tridecane - is obtained from lauryl (C12)/
April 2022 PERSONAL CARE The first step in its production
65
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116
