WAXES AND BUTTERS Tony O’Lenick – Siltech LLC, US The use of particular natural oils in formulations ABSTRACT CH2-OH O CH2-OC(O)-R Natural oils have become a common additive to personal care products. They CH-OH +3 RC-OH CH-OC(O)-R + 3 H2O fit the definition of natural, sustainable and can be renewable and even organic. CH OH CH -O-C(O)-R While these classifications are sometimes 2 2 unclear in meaning, the reason we formulate with a particular oil is often just Glycerin Fatty acid Triglyceride Water as obscure. Is it marketing, or carbon distribution or aesthetics or perhaps a Figure 1: The reaction.1 particular benefit rendered to the oil by a particular native material (antioxidants, The selection of a particular natural oil in triglycerides. Fats have a titer point of UV absorbers)? This article will look at a personal care application depends upon over 40.5˚C, oils have a titer point of some of these properties. what the formulator wants to achieve with below 40.5˚C. Butters have a titer below the particular formulation. The simplest 40.5˚C but above 20˚C. Oils are liquid choice is when the choice is simply a at room temperature and we now use point is generally determined on fats, oils, marketing choice. The product profile this word to describe any compound waxes and butters. may say that the product should contain that is a liquid and is insoluble in water.2 a particular oil like olive oil or argan oil. Because oils, fats, butters and waxes Triglycerides The aesthetics are dictated in large are complex mixtures of homologues of Triglycerides are the tri-esters of glycerin amount by two properties, carbon number similar chemical structures, it is difficult with three equivalents of organic acid. Fatty and amount of unsaturation (measured to obtain a true melting point. The term acids are defined as those acids having by iodine value). Finally, there may be a titer is therefore used to define the alkyl or alkylene groups being C-5 and particular reason to use an oil with an re-solidification point of the melted oil, higher. The reaction is shown in Figure 1. antioxidant or other active that is natural fat, butter or wax. The procedure is to When the triglyceride is saponified to to the oil. While seaming simple, once the heat the product to be tested until it is make a surfactant, such as soap, glycerin oil is chosen, the process by which the completely liquid, then to cool it slowly by is liberated. When a wax is saponified, oil was prepared becomes the controlling stirring. This is done until the temperature a fatty alcohol is liberated. Saponification factor. We will address each of these stays constant for 30 seconds, or begins is a general term to define the chemical variables. to rise. The titer point is the highest reaction that breaks the ester linkage. temperature indicated by this rise.1 This makes it possible to produce very Definitions As the lower molecular weight fractions different kinds of products using the two The terms oils, fats, butters and waxes melt, they act as solvents to dissolve the types of materials. have been misused over the years. The higher molecular weight products. This Glycerin, produced as a by-product of historical definition of wax has previous results in a very wide melting ‘range’ for saponification is water soluble and fatty been given. Butters, oils and fats are all these compounds. For this reason, titer insoluble. Table 1: Oil composition example. Table 2: Carbon number calculation for oil example in Table 1. Component % Weight (a) (b) C16 20 Component % Weight Carbon atoms Calculation in component (a)*(b) C18 20 C18:1† 20 C16 20 16 3.2 C20 40 C18 20 18 3.6 C18:1 20 18 3.6 Total 100 C20 40 20 8.0 †Note: C18:1 is our short to indicate the presence of 1 double bond or unsatuartion. Total 100 18.4 So C18:1 would be oleic acid Therefore for the Carbon number = 18.4 32 PERSONAL CARE March 2016 WAXES AND BUTTERS The fatty alcohol produced as a by- product of the saponification of a wax is 40 water insoluble and generally fatty-soluble. Triglycerides are commonly encountered as natural products. Plants use enzymatic s 30 de systems to make triglycerides, effectively ri ce at ambient temperatures. ly ig tr 20 INCI nomenclature f o INCI names require the genus and species er b of the plants or insects that produce a um 10 given wax, oil, butter or fat and all products N which are derived from the various oils, fats, butters and waxes. This is due, in part, to the European Union’s use of the 0 Latin names for ingredient listings. This Below 16 16-17 17-18 Over 18 Carbon number information is very helpful to the formulator in understanding the source of the fatty Figure 2: Carbon number of common triglycerides. portion of the surfactant. It is also quite interesting that nature Since few oils offer these high carbon Classification has provided many triglycerides that have numbers, manufacturers often fractionate In order to simplify the information, we very similar carbon numbers. In fact, methyl esters to pure compounds or, have divided the raw materials that we of 38 triglycerides presented here, 31 alternatively, they hydrogenate unsaturated discuss into two groups: those derived from have carbon numbers between 17 and 18. oils to make saturated compounds having animal sources and those derived from This also explains why the other important high carbon numbers. plant sources. Within each of these groups variable, unsaturation, is critical in In general, double bonds lower the one finds additional classes depending choosing an oil for a specific application titer point of the triglyceride, resulting upon the carbon distribution of the raw (Figs. 2 & 3). in a triglyceride that stays liquid at lower material. It is very interesting that there are only temperatures. Conjugated double bonds three triglycerides having a carbon number (i.e. those with only one carbon between Carbon number below 16. Since this is a key number for two double bonds (-C=C-C=C-), are very In addition to classifying products by their detergents, it becomes clear why coconut effective in depressing titer point, but can sources (animal or plant) and by their oil is so important to the surfactant present problems with rancidity, a process chemistry (triglyceride or ester), we have industry. There has been a growing by which the double bond is oxidised and classified them within these groups by demand for products based upon oils ultimately broken. This releases many carbon number and unsaturation level. having a carbon number over 18 (for different molecules, many of which have Carbon number is the value obtained by example behenic derivatives). In order to objectionable odors. Rancidity can be multiplying the percentage of a component get these products, one must choose a mitigated at times with the addition of in a product by the number of carbon different class of oils. The selection of the antioxidants, prior to the start of the atoms in the component, then adding up oil is a major variable, which normally rancidity process.3 all the components. eludes the formulator, being made more Finally, upon additional processing, For example, if an oil had the commonly by the derivative manufacturer. many oils, fats, butters and waxes lose composition shown in Table 1, the carbon Oil selection is assuredly one important their identity as oils and become known by number calculation would be as seen in factor in formulating cosmetic products. the fatty names of the predominant species Table 2. present after treatment. These processes There are several types of oils that have Effect of carbon number include preparation of methyl esters, very similar carbon numbers; consequently, One major factor that affects the we have classified them further by functionality of both the oil itself and any unsaturation. One can expect derivatives potential derivative is the number of carbon 5 8 from oils having very similar carbon atoms in the chain. Other factors include 5 numbers and levels of unsaturation to the number and location of double bonds have very similar, often identical functional and the presence of additional functional properties. In this instance, the choice groups. of which of the many oils to use depends Generally, as one evaluates the tactile upon the economics of the oil and the properties of an oil on the skin, the lower formulator’s desire to name the oil for label the molecular weight is, the less oily the ■ Below 16 and marketing purposes. As will become feel of the compound will be. Conversely, ■ 16-17 clear, there are many different fats, oils, the higher the molecular weight is, the ■ 17-18 waxes and butters, which when derivatised, more greasy the feel will be. In surfactant ■ Over 18 result in compounds of strikingly similar preparation, detergent products and high- carbon distributions, while having their foaming products generally peak between a source oil, wax, fat or butter being quite carbon number of 12 and 14. Conditioners 82 different. Thus, naming the material by and softeners have a carbon number of the predominant species is not very 16 to 18. Today there is a growing trend enlightening to the formulator as to the toward using materials with carbon Figure 3: Carbon number percentage shown source of the raw material. numbers of 22 or more for conditioning. in common triglycerides. March 2016 PERSONAL CARE 33 WAXES AND BUTTERS fractionation of the methyl ester and Table 3: Carbon number and iodine value for common triglycerides.2 preparation of a fatty alcohol.