Waxes

10 Key excerpts on "Waxes"

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  eBook - PDF

  Lipid Chemistry

  • Khetarpaul, Vipul(Authors)
  • 2021(Publication Date)
  • Daya Publishing House

    (Publisher)

  The collective properties of wax as just defined clearly distinguish Waxes from other articles of commerce. Chemically, Waxes constitute a large array of different chemical classes, including hydrocarbons, wax esters, sterol esters, ketones, aldehydes, alcohols, and sterols. The chain length of these components may vary from C 2 , as in the acetate of along chain ester, to C 62 in the case of some hydrocarbons. Waxes can be classified according to their origins as naturally occurring or synthetic. The naturally occurring Waxes can be subclassitied into animal, vegetable, and mineral Waxes. Beeswax, spermaceti, wool grease, and lanolin are important animal Waxes. Beeswax, wool grease, and lanolin are by-products of other industries. The vegetable Waxes include carnauba wax, the so-called queen of Waxes, ouricouri (another palm wax), and candelilla. These three Waxes account for the major proportion of the consumption of vegetable Waxes. The mineral Waxes are further classified into the petroleum Waxes, ozokerite, and montan. Based on their chemical structure, Waxes represent a very broad spectrum of chemical types from polyethylene, polymers of ethylene oxide, derivatives of montan wax, alkyl esters of monocarboxylic acids, alkyl esters of hydroxy acids, polyhydric alcohol esters of hydroxy acids, Fisher- Trop-sch Waxes, and hydrogenated Waxes, to long chain amide Waxes. This ebook is exclusively for this university only. Cannot be resold/distributed. The ancient Egyptians used beeswax to make writing tablets and models, and Waxes are now described as man’s first plastic. Indeed, the plastic property of Waxes and cold-flow yield values allow manual working at room temperature, corresponding to the practices of the Egyptians. The melting points of Waxes usually vary within the range of 40 to 120°C. Waxes dissolve in fat solvents, and their solubility is dependent on temperature.

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  Encyclopedia of Pharmaceutical Technology

  Volume 6

  • James Swarbrick(Author)
  • 2013(Publication Date)
  • CRC Press

    (Publisher)

  Water–Zeta Waxes Roland A. Bodmeier College of Pharmacy, Freie Universita¨t Berlin, Berlin, Germany INTRODUCTION The term wax generally refers to a substance that is a plastic solid at room temperature and a liquid of low viscosity above its melting point. Strictly speaking, a wax is chemically defined as an ester of a monohydric long chain fatty alcohol and a long chain fatty acid. However, generally the term wax has been applied to a broad group of chemically heterogeneous materials. Waxes usually contain a wide variety of materials including glycerides, fatty alcohols, fatty acids, and their esters. In the pharmaceutical literature, the terms Waxes, fats, or lipids have often been used inter-changeably and no consistent terminology has been established. They have in common their lipophilic character and their insolubility in water and solubility in non-polar solvents. Besides natural materials, many semisynthetic products such as fatty acids or alcohols or surfactants are derived from lipids. Waxes have been used by the pharmaceutical indus-try for many years. Their applications in semisolid pre-parations, including ointments, creams, or lotions, and in suppositories are well known and numerous publica-tions exist on this topic. Because of their lipophilic properties, Waxes have been used in sustained-release single or multiple unit solid dosage forms. This article reviews the different uses of Waxes as sustained-release carrier or coating materials. Waxes IN PHARMACEUTICAL DOSAGE FORMS Waxes are obtained from various sources and are gen-erally classified into animal, insect, vegetable, mineral, and synthetic Waxes. [1–7] The most familar animal wax is probably lanolin, which is obtained from the wool of the sheep. It con-sists primarily of esters of C 18 –C 26 alcohols and fatty acids, sterols (cholesterol), and terpene alcohols. It is frequently used in topical preparations. Until recently, spermaceti was another commonly used animal wax.

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  eBook - ePub

  Development of Trans-free Lipid Systems and their Use in Food Products

  • Jorge F Toro-Vazquez(Author)
  • 2022(Publication Date)
  • Royal Society of Chemistry

    (Publisher)

  Overall, natural Waxes, particularly vegetal Waxes, are efficient gelators of vegetable oils at concentrations lower than 10 wt%. The resulting oleogels usually have functional properties suitable for their use in edible and cosmetic products. Their functionality is often linked to their chemical composition. Some vegetable Waxes have a relatively low price and are commercially abundant, although this does not apply to all of them. 14 – 17 A few plant Waxes, like sunflower wax, are by-products of agricultural and industrial processes, so new applications might increase their market value. 18, 19 From a chemical perspective, a wax has been described as an ester of a monohydric long chain alcohol with a long chain acid. 20 However, when referring to natural Waxes, the terminology “wax” is used to describe the complex mixtures of long chain compounds that cover the surfaces of several organisms. The composition of these mixtures varies among organisms and contains different chemical substances such as hydrocarbons, free fatty alcohols, free fatty acids, and wax esters (Scheme 9.1). Ketones, mono-, di-, triacylglycerols, and sterol esters can also be present in various concentrations. 13, 20, 21 Scheme 9.1 Structures of the main chemical components in natural Waxes. The exact composition differs between Waxes of different sources. For example, berry wax has different chemical constituents than candelilla wax and beeswax. In addition, there are chemical differences when comparing the same type of wax from different suppliers

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  eBook - ePub

  Materials Science for Dentistry

  • B W Darvell, B. W. Darvell(Authors)
  • 2009(Publication Date)
  • Woodhead Publishing

    (Publisher)

  Waxes have a wide variety of types of application in dentistry, ranging from taking impressions, making patterns for lost-wax casting and acrylic denture baseplates, for bite detection, blocking out undercuts on models, the masking of regions to be protected in electroplating, and the temporary cementing of models. Even given this range of applications, the selection of Waxes to do all of these jobs is of course coincidental, essentially relying on just one or a few of the characteristic properties of this class of materials.

  §1 Chemistry

  Waxes are not defined chemically but rather they take their name in allusion to beeswax, which in view of the presumed antiquity of its knowledge may fairly be called the archetype of all Waxes. Beeswax is largely a collection of long chain esters, and it will be shown that this chemistry is associated with a kind of structure that leads to the same general properties arising both in a range of pure substances as well as their mixtures.

  The simplest Waxes are the alkanes (Cn H2n+2 ), whether straight chain or branched, and these paraffins may be considered as Waxes when they are solid at room temperature or thereabouts. Thus, for n = 17, the melting point is about 22 °C. There is no effective upper limit to n. Polyethylene, named more from its manufacturing route than what for it is, an alkane, may also be considered as a wax, where n is then counted in the thousands or tens of thousands. Indeed, it may be used in some dental products. However, a typical practical limit to dental usefulness for alkanes is with n ~ 60.

  The alkanols (Cn H2n+1 OH) and alkanoic acids (Cn H2n+1 COOH) are also Waxes if n is large enough, but in fact they are not very common as constituents of the natural products employed in dental wax manufacture. On the other hand, esters are very common (see beeswax, above), especially as plant products. In the general formula for saturated esters, Cn H2n+1 .COO.Cm H2m+1 , m and n may both be in the range 15 - 30. Similar length chains are found in the unsaturated esters, and in all similar compounds that exhibit beeswax-like properties, i .e

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  Organic Chemistry

  • David R. Klein(Author)
  • 2016(Publication Date)
  • Wiley

    (Publisher)

  In this chapter, we will explore three such classes: steroids, prostaglandins, and ter- penes. One example of each class is shown below. HO H H H H H Cholesterol (a steroid) COOH OH HO HO PGF 2α (a prostaglandin) Limonene (a terpene) 26.2 Waxes Waxes are high-molecular-weight esters that are constructed from carboxylic acids and alcohols. For example, triacontyl hexadecanoate, a major component of beeswax, is constructed from a carboxylic acid with 16 carbon atoms and an alcohol with 30 carbon atoms. O O 16 Carbon atoms 30 Carbon atoms Triacontyl hexadecanoate (a major component of beeswax) Other Waxes are similar in structure, differing only in the number of carbon atoms on either side of the ester group. These long hydrocarbon chains endow these compounds with high melting points as the result of extensive, intermolecular London dispersion forces between the hydrocar- bon tails. Waxes serve a wide variety of functions in living organisms. Sperm whales are believed to use spermaceti wax as an antenna for detecting sound waves (sonar), allowing the whale to map its envi- ronment. Many insects have protective coatings of wax on their exoskeletons. Birds utilize Waxes on their feathers, rendering them water repellant. Similarly, the fur of some mammals, such as sheep, is coated with a mixture of Waxes called lanolin. Waxes coat the surface of the leaves of many plants, thereby preventing evaporation and reducing water loss. For example, carnauba wax (a mixture of high-molecular-weight esters) is produced by the Brazilian palm tree and is commonly used in polish formulations for boats and automobiles. LOOKING BACK For a review of London dispersion forces, see Section 1.12. 26.3 Triglycerides 1193 26.3 Triglycerides The Structure and Function of Triglycerides Triglycerides are triesters formed from glycerol and three long-chain carboxylic acids, or fatty acids (Figure 26.2). CONCEPTUAL CHECKPOINT 26.1 Waxes can be hydrolyzed to yield an alcohol and a carboxylic acid.

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  Klein's Organic Chemistry

  • David R. Klein(Author)
  • 2020(Publication Date)
  • Wiley

    (Publisher)

  In this chapter, we will explore three such classes: steroids, prostaglandins, and ter- penes. One example of each class is shown below. HO H H H H H Cholesterol (a steroid) COOH OH HO HO PGF 2α (a prostaglandin) Limonene (a terpene) 26.2 Waxes Waxes are high-molecular-weight esters that are constructed from carboxylic acids and alcohols. For example, triacontyl hexadecanoate, a major component of beeswax, is constructed from a carboxylic acid with 16 carbon atoms and an alcohol with 30 carbon atoms. O O 16 Carbon atoms 30 Carbon atoms Triacontyl hexadecanoate (a major component of beeswax) Other Waxes are similar in structure, differing only in the number of carbon atoms on either side of the ester group. These long hydrocarbon chains endow these compounds with high melting points as the result of extensive, intermolecular London dispersion forces between the hydrocar- bon tails. Waxes serve a wide variety of functions in living organisms. Sperm whales are believed to use spermaceti wax as an antenna for detecting sound waves (sonar), allowing the whale to map its envi- ronment. Many insects have protective coatings of wax on their exoskeletons. Birds utilize Waxes on their feathers, rendering them water repellant. Similarly, the fur of some mammals, such as sheep, is coated with a mixture of Waxes called lanolin. Waxes coat the surface of the leaves of many plants, thereby preventing evaporation and reducing water loss. For example, carnauba wax (a mixture of high-molecular-weight esters) is produced by the Brazilian palm tree and is commonly used in polish formulations for boats and automobiles. LOOKING BACK For a review of London dispersion forces, see Section 1.12. 1184 CHAPTER 26 Lipids 26.3 TRIGLYCERIDES The Structure and Function of Triglycerides Triglycerides are triesters formed from glycerol and three long-chain carboxylic acids, or fatty acids (Figure 26.2). Conceptual CHECKPOINT 26.1 Waxes can be hydrolyzed to yield an alcohol and a carboxylic acid.

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  eBook - ePub

  Lubricants and Waxes

  From Basics to Applications

  • Dhananjoy Ghosh(Author)
  • 2023(Publication Date)
  • CRC Press

    (Publisher)

  Wax can be of different categories. The above method of wax production comes under petroleum wax category but the wax in it comes under mineral wax category; similarly, Waxes obtained from animal and vegetable sources come under natural wax category. On the other hand, if the wax is produced by chemical reactions within one or between two components, the wax obtained is called synthetic wax; for example, in the process of producing polyethylene from ethylene, the process can be controlled in such a way that polymerization can be terminated mid-way to get waxy ethylene, i.e. polymerization to stop after carbon number reaches to about 20; the wax formed should be called a by-product synthetic wax. But if the wax is produced starting with one or two single compounds reacting and polymerizing with objective to produce wax only as the main product, it is called fully synthetic wax.

  From view point of feed sources, Waxes then can be categorized as follows:

  • Natural Waxes:
    • Animal wax:
      • Beeswax, Chinese wax, Shellac wax, Spermaceti wax, Lanolin (wool wax).
    • Vegetable wax:
      • Bayberry wax, Candelilla wax, Castor wax, Esparto wax, Japan wax, Ouricury wax, Rice bran wax, Soy wax.
    • Mineral wax:
      • Petroleum wax:
        • Crude oil distillates, Crude oil tank bottoms.
      • Other mineral wax:
        • Ceresin wax, Montan wax, Ozocerite wax, Peat wax.
  • Synthetic wax:
    • Polyethylene wax (PE wax).
    • Fischer Tropsch wax.
    • Chemically modified wax.
    • Substituted amide wax.
    • Polymerized alpha olefin wax (PAO wax).

  4.1 Properties and Significance

  Though wax is a solid product, it remains in plastic stage unlike metals, i.e. it can be bent by applying minor force. Like lube base oils, wax also has its own specific physico-chemical properties which should be met to use the wax for commercial purpose. The most important properties are discussed as follows:

  • Oil content: Residual oil content should be minimum as per specification to keep it in solid form and prevent it from becoming soft or semi-solid during storage at high ambient temperature. The oil content is measured as %wt. of the wax sample.
  • Drop melting point: It is the temperature at which the wax sample initiates melting, i.e. when first drop of melt forms. It is generally measured as °C. If oil content of the wax is higher, its drop melting point (DMP) would be lower and vice versa. Even with low oil content of wax, its DMP may be lower which is due to the crystalline structure of wax which however is benchmarked in such cases and incorporated in the specifications; this structure of wax has been discussed separately in the ‘classification of wax’ as follows.

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  eBook - PDF

  Food Lipids

  Chemistry, Nutrition, and Biotechnology, Fourth Edition

  • Casimir C. Akoh(Author)
  • 2017(Publication Date)
  • CRC Press

    (Publisher)

  It is well established that the very long carbon skeletons of the wax lipids are synthesized by a con- densation–elongation mechanism. The primary elongated products in the form of free fatty acids are often minor components of epicuticular Waxes. Most of them, however, serve as substrates for the associated enzyme systems discussed. The total length attained during elongation is reflected by the chain lengths of the members of the various wax classes [15–21]. Normal, branched, and unsaturated hydrocarbons and fatty acids are prominent components of plant Waxes, whereas insect Waxes usually lack long-chain free fatty acids [22–26]. II. CHEMISTRY OF STEROLS A. INTRODUCTION Sterols are a subclass of steroids. The International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Biochemistry have defined steroids as, “compounds possessing the skeleton of cyclopenta[ α]phenanthrene or a skeleton derived therefrom by one or more bond scis- sions or ring expansions or contractions” [27]. In summary, most steroids have four fused rings, as shown in Figure 4.1. These four rings, considered the steroid “nucleus,” are labeled A through D. IUPAC appoints “steroids carrying a hydroxyl group at C3 and most of the skeleton of cholestane” as sterols [27]. Thus, compounds with a hydroxyl group at the C3 position and the four fused rings seen in Figure 4.1 are classified sterols by the IUPAC. More recently, sterols were defined in Chemical Reviews as “amphipathic compounds that origi- nate in isoprenoid biosynthesis with the main frame composed of a nucleus and a side chain” [28]. This interesting definition divides steroids that lack a side chain, particularly androgens and estro- gens, from other sterols.

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  The Lipid Handbook with CD-ROM

  • Frank D. Gunstone, John L. Harwood, John L. Harwood(Authors)
  • 2007(Publication Date)
  • CRC Press

    (Publisher)

  Data from Jacob (1976). Occurrence and Characterisation of Oils and Fats 111 usually have C 16 and C 18 saturated and unsaturated acyl groups. Sterols are often found in small amounts, with cholesterol the most common compound. Primary alco-hols and nonesterified fatty acids are both usually even-chain compounds. 2.5.3.1 Occurrence and characteristics A general source of information is Stanley-Samuelson and Nelson (1993). The biosynthesis of the individual insect wax components is discussed by Jackson and Blomquist (1976). Chemical analysis of insect Waxes is reviewed by Lockey (1985) and Nelson (1978), and recent aspects of this and biosynthesis can be found in Nelson and Blomquist (1996). Over a hundred insect species have now been studied and many of their hydrocarbons function as sex phenomones, antiaphrodisiacs and kairomones, in addition to their role as waterproofing chemicals. In addition, recent work shows that the hydrocarbons may be present internally in larger amounts than on the surface and that changes in composition may occur sooner for the internal fraction. Insect hydrocarbons are being used increasing as chemotaxonomic characters (Nelson and Blomquist, 1996). 2.5.4 Plant Waxes Epicuticular wax of plants lies on and is interspersed with the insoluble part of the leaf cuticle known as cutin (see Section 1.2.12). The major components are indicated in Table 2.91. Thus, n-alkanes, monoesters, polyesters of ω -hydroxy acids, primary alcohols, acids, secondary alco-hols and ketones, and β -di-ketones can be generally regarded as widespread and major constituents (Tulloch, 1976) (cf. Table 2.92). The chain lengths of the hydrocarbons and primary alcohols of some frequently analysed Waxes are shown in Table 2.93. Hydrocarbons of C 27 , C 29 , and C 31 are the most common, while the free alcohols are usually of C 26 , C 28 , and C 30 .

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  Paraffin

  an Overview

  • Fathi Samir Soliman(Author)
  • 2020(Publication Date)
  • IntechOpen

    (Publisher)

  Chapter 2 Wax Chemical and Morphological Investigation of Brazilian Crude Oils Erika C.A. Nunes Chrisman, Angela C.P. Duncke, Márcia C.K. Oliveira and Márcio N. Souza Abstract The Waxes in petroleum can precipitate and form unwanted gels and deposition when exposed to low temperatures. The idea of this chapter is to approach methods of quantification and physicochemical and morphological characterization of Waxes and how this information can help in understanding this deposition. Information such as the quantity of Waxes and the chemical structures in the oil is fundamental to predict the possible deposition and its ability to aggregate with other crystals. For example, the knowledge about the wax morphology may contribute to explain the nucleation and growth of the deposits. The polarized light microscopy, the most common technique to visualize wax crystals, and the bright-field microscopy, the most simple technique, able to show crystal details that have not been seen on the polarized light, was used. Keywords: Waxes, crude oil, quantification, characterization, microscopy, DSC 1. Introduction Petroleum is a complex mixture of hydrocarbons of varying nature and small fractions of nitrogen, oxygen, sulfur, and metal compounds. At room temperature, petroleum can be gas, liquid, and/or solid, being considered as gases and solids dispersing in a liquid phase [1]. Under high temperature and pressure, as encoun-tered at reservoirs (e.g., 8000 – 15,000 psi and 70 – 150°C), Newtonian rheological behavior prevails, whereas at low temperatures the pseudoplastic behavior is com-monly found [2]. A large portion of the Brazilian oil production comes from offshore fields, from the pre-salt layer. These oils have high levels of Waxes, which are alkanes (linear or branched) encompassing carbonic chains of 15 – 75 carbons [3, 4]. This class of compounds has a high precipitation potential, due to the low sea temperatures (about 4 – 5°C) [5 – 7].

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