الفهرس 
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Abstract
removal of glycerol moiety, As mentioned before, fatty acids can be classified into two classes. the first isFatty acid is a carboxylic acid often with a long aliphatic chain, which is either saturated of unsaturated. Fatty acid and their derivatives are consumed in a wide variety because they are used as raw materials for a wide variety of industrial products like, paints, surfactant, textiles, plastics, rubber, cosmetics, foods, and pharmaceuticals.
Industrially, fatty acids are produced by the hydrolysis of triglycerides, with the unsaturated fatty acid with one or more double bonds in the alkyl chain and the other is saturated fatty acid.
Long chain 3-alkenoic acids are a family of polyunsaturated fatty acids which have in common a carbon-carbon double bond in the position 3.
They are used as key precursors for synthesis of many organic compounds. There are many methods for the synthesis of such acids; here we will mention two of these methods.
Nucleophilic substitution of allylic substrates with organometallic reagents, treatment of β-vinyl β-propiolactone with butylmagnesium bromide in the presence of copper(I) iodide in THF at -30 0 c, gave 3-nonenoic acid as a major product and 3-butyl-4-pentenoic acid with the ratio 98:2 respectively[1] .
Knoevenagel condensation of an aldehyde with malonic acid in the presence of organic bases was considerable value for the synthesis of unsaturated fatty acids. This reaction is mainly related to its application for the synthesis of α-β-unsaturated fatty acids. For the synthesis of β-α- unsaturated fatty acids the Linstead modification [2] of the Knoevenagel condensation, in which triethanolamine or other tertiary amines are used. It gives modest yield of 3-alkenoic acid.
Corey [3,4] has posulated the possibility to orient the Knoevevagel condesation for the synthesis of 2- or 3-unsaturated acids in a predictable way, by modifying the base strength and polarity of the medium. On the other hand, 3-alkenoic acids of high stereochemical purity were prepared by Ragoussis [5] in good yield by reaction of various aliphatic aldehydes with a three-molar excess of malonic acid and piperidinium acetate as a base in xylene.
Also, Rao et al [6] used equimolar ratios of malonic acid and aldehydes with triethylamine as a base as well as solvent to give (E) 3-alkenoic acids in good yield, ranging from 80-88%. This method avoids the use of large molar excess of expensive malonic acid, and the reaction conditions are easily attained.
Recently 3-alkenoic acids were obtained in high yields and stereochmeical purity when equimolar quantities of aliphatic aldehydes with a microwave irradiation [7] .
The following investigation deals, with the surface active agents which are one interesting applications of fatty acids.
Surface active agents
The surface active agents[8] (surfactants), literally means active at a surface. In other words, a surfactant is characterized by its tendency to adsorb at surfaces and interfaces. The term interface denotes a boundary between any two immescible phases, while the term surface indicates that one of the phases is gas, usually air.
There are five different interfaces exist:
Solid - Vapour, Solid - Liquid, Solid - Solid, Liquid - Vapour and Liquid - Liquid. The driving force for a surfactant to adsorb at an interface is to lower the free energy of that phase boundary. The interfacial free energy per unit area represents the amount of work required to expand the interface.
The term interfacial tension is often used instead of interfacial free energy per unit area. Thus, the surface tension of water is equivalent to the interfacial free energy per unit area of the boundary between water and the air above it. When that boundary is covered by surfactant molecules, the surface tension (or the amount of work required to expand the interface) is reduced.
The tendency to accumulate at interfaces is a fundamental property of a surfactant. In principle, the stronger the tendency, the better is the surfactant.
The degree of surfactant concentration at a boundary depends on surfactant structure and also on the nature of the two phases that meet at the interface.
Therefore, there is no universally good surfactant suitable for all uses. The choice will depend on the application.
A good surfactant should have low solubility in the bulk phases. Some surfactants are only soluble at the oil-water interface. Such compounds are difficult to handle but are very efficient in reducing the interfacial tension.
There is of course a limit to the surface and interfacial tension lowering effect by the surfactant. In the normal case that limit is reached when micelles start to form in bulk solution.
The many guises of surfactants functional names:
Wetting Agents Soaps
Emulsifiers Detergents
Demulsifires Sanitizers
Dispersants Tenside
Corrosion Inhibitors Solubilizers
Foam Boosters Antistatic Agents
Defoamers Plasticizers
Surfactants are Amphiphilic:
The name amphiphile is sometimes used synonymously with surfactant. The word derived from the Greek word amphi, meaning both, and the term relates to the fact that all surfactants molecules consist of at least two parts, one which is soluble in a specific fluid (the Lyophilic part) and one which is insoluble (the Lyophobic part).
When the fluid is water one usually talks about the Hydrophilic and Hydrophobic parts, respectively. The Hydrophilic part is referred to as the head group and the Hydrophobic part as the tail, see figure(1).
Fig.( 1). Schematic illustration of surfactant
When a surfactant adsorbs from aqueous solution at a hydrophobic surface, it normally orients its hydrophobic group towards the surface and exposes its polar group to the water. The surface has become hydrophilic and as a result the iterfacial tentsion between the surface and water has been reduced.
Adsorption at hydrophilic surfaces often results in more complicated surfactant assemblies.
The hydrophobic part of a surfactant may be branched or linear. The polar head group is usually but not always attached at one end of the alkyl chain. The length of the chain is in the range of 8-18 carbon atoms.
The hydrophobic group is normally hydrocarbon (alkylaryl) but may also be polydimethylsiloxane or fluorocarbon. The two latter types of surfactants are particularly effective in non-aqueous systems. The polar part of the surfactant may be ionic or non-ionic and the choice of polar group determines the properties to a large extent.
A surfactant usually has one polar group. Recently, there has been valuable research in certain dimeric surfactants, containing two hydrophobic tails and two head groups linked together with a short spacer.
These species, generally known under the name gemini surfactants, are not yet of commercial importance.
Weakly surface active compounds which accumulate at interfaces but which don’t readily from micelles are of interest as additives in many surfactant formulations. They are referred to as hydrotropes. Addition of hydrotropes is a way to prevent the formation of highly viscous liquid crystalline phases which constitutes a well-known problem in surfactant formulation. Xylene sulfonate and cumene sulfonate are typical examples of hydrotropes used.
Classification of surfactants
The primary classification of surfactants is made on the basis of the charge of the polar head group. It was divided into four different main types, anionics, cationics, nonionics and amphoteric surfactants. Anionic and cationic surfactants carry negative and positive charges on their head groups, respectively; the nonionics are uncharged head group, and amphoteric surfactants which may be anionic or cationic depending in the PH of the solution, (see Fig .2).
Fig. 2. The four different main types of surfactants.
1. Anionic surfactants:
These are consisting of a linear or branched chain with polar negative group (carboxylate, sulfate, sulfonate or phosphate ) which is response for surface character.
They are capable of undergoing ionization in solution to oil soluble anion and metallic cation. The most common cation used are sodium and potassium. Examples of anionic surfactants (Fig.3)
(Fig. 3)
2. Cationic surfactants:
They are consist of a hydrophobic hydrocarbon group and one or more hydrophilic groups which dissociate in aqueous medium. Most of their hydrophilic groups have a nitrogen atom carrying the positive charge which is the carrier of the surface active properties of this type. Examples of cationic surfactants (Fig.4).