Saponification- This is the hydrolysis of esters under the influence of alkali. This produces a salt of an organic acid and an alcohol. Historically, this name comes from the process of making soap - hydrolysis of fats with lye, which produces a mixture of salts of higher fatty acids (actually soap) and glycerin (trihydric alcohol).
Respectively saponification is the reaction of an ester with an alkali.

Before the invention of soap, fat and dirt were removed from the skin using ash and fine river sand. The technology for making soap from animal fats evolved over many centuries. Let's see how you can make soap in a chemistry laboratory. First, a fat mixture is prepared, which is melted and saponified - boiled with alkali. To hydrolyze fat in an alkaline environment, take a little rendered lard, about 10 ml of ethyl alcohol and 10 ml of alkali solution. Table salt is also added here and the resulting mixture is heated. This produces soap and glycerin. Salt is added to precipitate glycerin and impurities. Soap is also produced industrially.

Soap composition
Soaps are sodium or potassium salts of higher carboxylic acids (acids containing more than 10 carbon atoms), obtained as a result of the hydrolysis of fats in an alkaline environment (most often from fats containing stearic acid C 17 H 35 COOH) - C 17 H 35 COONa – sodium stearate.
Fat + alkali = fatty acid salts and glycerol.

Properties of soap
The surface layer of distilled water is in a tense state like an elastic film. When soap and some other water-soluble substances are added, the surface tension of water decreases. Soap and other detergents are classified as surfactants (surfactants). They reduce the surface tension of water, thereby enhancing the cleaning properties of water.

Molecules located on the surface of a liquid have an excess of potential energy and therefore tend to be drawn inward so that a minimum number of molecules remain on the surface. Due to this, a force always acts along the surface of the liquid, tending to reduce the surface. This phenomenon in physics is called surface tension of a liquid.

The surfactant molecules on the boundary surface are arranged in such a way that the hydrophilic groups of carboxyl anions are directed into the water, and the hydrophobic hydrocarbon groups are pushed out of it. As a result, the surface of the water is covered with a palisade of surfactant molecules. Such a water surface has lower surface tension, which facilitates rapid and complete wetting of contaminated surfaces. By reducing the tension surface of water, we increase its wetting ability.

The secret of the cleansing effect of soap

SMC (synthetic detergents) are sodium salts of synthetic acids (sulfonic acids, esters of higher alcohols and sulfuric acid).
Let's consider the properties of detergents and compare soap and SMS (washing powder). First, let's check what environment is typical for our detergents. How do we do this?
Using indicators.
We will use indicators known to us - litmus and phenolphthalein. When litmus is added to a soap solution and to an SMS solution, it becomes blue, and phenolphthalein becomes crimson, that is, the reaction of the medium is alkaline.

What happens to soap and SMS in hard water? (it’s clear why soap makers don’t make soap using tap water, but use decoctions, distilled water, milk, etc.)
Add the soap solution to one test tube and the SMS solution to the other, shake them up. What are you observing? Add calcium chloride to the same test tubes and shake the contents of the test tubes. What are you observing now? The SMS solution foams, and insoluble salts form in the soap solution:
2C 17 H 35 COO – + Ca 2+ = Ca(C 17 H 35 COO) 2
And SMCs form soluble calcium salts, which also have surface-active properties.
Using excessive amounts of these products leads to environmental pollution. Let's listen to a message about the environmental consequences of using surfactants.
Many surfactants are difficult to biodegrade. When wastewater enters rivers and lakes, it pollutes the environment. As a result, whole mountains of foam are formed in sewer pipes, rivers, lakes, where industrial and domestic wastewater ends up. The use of some surfactants leads to the death of all living inhabitants in the water.

Why does a soap solution quickly decompose when it gets into a river or lake, but some surfactants do not? The fact is that soaps made from fats contain unbranched hydrocarbon chains that are destroyed by bacteria. At the same time, some SMCs contain alkyl sulfates or alkyl (aryl) sulfonates with hydrocarbon chains having a branched or aromatic structure. Bacteria cannot “digest” such compounds. Therefore, when creating new surfactants, it is necessary to take into account not only their effectiveness, but also their ability to biodegrade - to be destroyed by certain types of microorganisms.

The structure of soap, its properties

Soaps are sodium or potassium salts of higher fatty acids (Scheme 1), which hydrolyze in an aqueous solution to form acid and alkali.

General formula of solid soap:

Salts formed by strong alkali metal bases and weak carboxylic acids undergo hydrolysis:

The resulting alkali emulsifies, partially decomposes fats and thus releases dirt stuck to the fabric. Carboxylic acids form foam with water, which captures dirt particles. Potassium salts are more soluble in water than sodium salts and therefore have stronger cleaning properties.

The hydrophobic portion of the soap penetrates the hydrophobic contaminant, resulting in the surface of each contaminant particle being surrounded by a shell of hydrophilic groups. They interact with polar water molecules. Due to this, the ions of the detergent, along with the contamination, are detached from the surface of the fabric and pass into the aqueous environment. This is how the contaminated surface is cleaned with a detergent.

Soap production consists of two stages: chemical and mechanical. At the first stage (soap cooking), an aqueous solution of sodium (less often potassium) salts, fatty acids or their substitutes is obtained.

Production of higher carboxylic acids during cracking and oxidation of petroleum products:

Preparation of sodium salts:

WITH n H m COOH + NaOH = C n H m COONa + H 2 O.

Soap cooking is completed by treating the soap solution (soap glue) with excess alkali or sodium chloride solution. As a result, a concentrated layer of soap, called a core, floats to the surface of the solution. The resulting soap is called sound soap, and the process of isolating it from the solution is called salting out or salting out.

Mechanical processing consists of cooling and drying, grinding, finishing and packaging of finished products.

As a result of the soap-making process, we obtain a wide variety of products that you can familiarize yourself with.

The production of laundry soap is completed at the salting out stage, during which the soap is cleaned from protein, coloring and mechanical impurities. The production of toilet soap goes through all stages of mechanical processing. The most important of these is grinding, i.e. transferring sound soap into a solution by boiling with hot water and salting out again. In this case, the soap turns out to be especially clean and light.

Washing powders can:

Irritate the respiratory tract;

Stimulate the penetration of toxic substances into the skin;

Cause allergies and skin dermatitis.

In all these cases, you need to switch to using soap, the only drawback of which is that it dries out the skin.

If the soap was made from animal or vegetable fats, then glycerin formed during saponification is separated from the solution after separating the kernel, which is widely used: in the production of explosives and polymer resins, as a fabric and leather softener, in the manufacture of perfumes, cosmetics and medical preparations, in production of confectionery products.

In the production of soap, naphthenic acids are used, released during the purification of petroleum products (gasoline, kerosene). For this purpose, petroleum products are treated with a solution of sodium hydroxide and an aqueous solution of sodium salts of naphthenic acids is obtained. This solution is evaporated and treated with table salt, as a result of which a dark-colored, ointment-like mass—soap naft—floats to the surface of the solution. To clean soaponaft, it is treated with sulfuric acid. This water-insoluble product is called asidol or asidol-mylonaft. Soap is made directly from asidol.

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Vaseline" href="/text/category/vazelin/" rel="bookmark">Vaseline-lanolin soap is prepared as follows: take 3.5 kg of petroleum jelly and 1.5 kg of lanolin, add them to 95 kg of molten soap mass. Used petroleum jelly-lanolin soap as a skin softener. Medical soaps also include liquid potassium soap, which is prepared from liquid vegetable oils by saponification with caustic potassium; fatty acid content is at least 40%. Medical soap used externally in the forms of plasters, ointments, pastes , has a therapeutic value in accordance with the effect of the active principle added to the soap. This is the use of turpentine soap in the form of an ointment for rheumatism.

Special types of soap also include soaps used mostly in the textile, leather, metallurgical industries, in the production of insectofungicides, etc. Special soaps are known mainly in liquid form, prepared by saponifying a fat mixture with sodium or potassium alkalis or a mixture thereof.

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The effect of soap composition on the skin.

There are a great many varieties and brands of soap, and before choosing the most suitable one, you need to determine your skin type.

Oily skin often becomes shiny due to heavy sweating and oil production, and it usually has large pores. Already 2 hours after washing, oily skin leaves spots on a napkin applied to the face. Skin like this needs soap

with a slight drying effect.

Dry skin is thin and very sensitive to wind and bad weather, and its pores are small and thin; it cracks easily because it is not elastic enough. Such skin needs to be created with maximum comfort and gentle treatment, better

use expensive types of soap.

Normal skin is soft, smooth, and has medium-sized pores. Such skin seems to “glow”, but does not shine. However, normal skin, like any other, needs careful care.

Soaps made from short-carbon chain fatty acids (lauric and myristic) and long-carbon chain unsaturated fatty acids (oleic). Irritating to skin. Soap made from saturated fatty acids with a long carbon chain (palmitic and stearic) does not irritate the skin. Alkaline and acidic soaps can irritate the skin, exposing it to germ attack. It is better to use neutral soap

Raw materials for soap production

Animal and vegetable fats, fat substitutes (synthetic fatty acids, rosin, naphthenic acids, tall oil) can be used as raw materials to obtain the main component of soap. Animal fats– an ancient and very valuable raw material for soap-making surfaces. They contain up to 40% saturated fatty acids. Artificial, that is, synthetic, fatty acids are obtained from petroleum paraffin by catalytic oxidation with atmospheric oxygen. During oxidation, the paraffin molecule is broken in different places, and a mixture of acids is obtained, which are then separated into fractions. In soap production, mainly two fractions are used: C10-C16 and C17-C20. Synthetic acids are introduced into laundry soap in an amount of 35-40%. Naphthenic acids, released during the purification of petroleum products (gasoline, kerosene, etc.), are also used for soap production. For this purpose, petroleum products are treated with a solution of sodium hydroxide and an aqueous solution of sodium salts of naphthenic acids (monocarboxylic acids of the cyclopentane and cyclohexane series) is obtained. This solution is evaporated and treated with table salt, as a result of which a dark-colored, ointment-like mass, soap naft, floats to the surface of the solution. To purify soap naphtha, it is treated with sulfuric acid, that is, the naphthenic acids themselves are displaced from the salts. This water-insoluble product is called asidol, or asidolmylonaft. Only liquid or, in extreme cases, soft soap can be made directly from asidol. It has an oily smell, but it has bactericidal properties.

In the production of soap, rosin has long been used, which is obtained by processing the resin of coniferous trees. Rosin consists of a mixture of resin acids containing about 20 carbon atoms in the carbon chain. 12-15% of rosin by weight of fatty acids is usually added to the composition of laundry soap, and no more than 10% is added to the formulation of toilet soaps. The introduction of rosin in large quantities makes the soap soft and sticky.

Soap making technology.

The production of soap is based on the saponification reaction - the hydrolysis of fatty acid esters (i.e. fats) with alkalis, which results in the formation of alkali metal salts and alcohols.

In special containers (digesters), heated fats are saponified with caustic alkali (usually caustic soda). As a result of the reaction in digesters, a homogeneous viscous liquid is formed, thickening when cooled - soap glue, consisting of soap and glycerin. The fatty acid content of soap obtained directly from soap glue is usually 40-60%. This product is called " glue soap" The method of producing adhesive soap is usually called the “direct method”.

The "indirect method" of producing soap involves further processing of soap glue, which is subjected to relief- treatment with electrolytes (solutions of caustic alkali or sodium chloride), resulting in separation of the liquid: the top layer, or soap core. Contains at least 60% fatty acids; bottom layer - soap lye, an electrolyte solution with a high glycerol content (also contains contaminants contained in the feedstock). The soap obtained as a result of the indirect method is called “ sound».

Highest grade soap - sawed, obtained by grinding dried sound soap on rollers sawing cars. At the same time, the content of fatty acids in the final product increases to 72-74%, the structure of the soap improves, its resistance to drying out, rancidity and high temperatures during storage. When caustic soda is used as an alkali, solid sodium soap is obtained. A mild or even liquid potassium soap is formed when caustic potash is used.

Now we’ll talk about soap production technology. To prepare simple solid soap, take 2 kg of caustic soda and dissolve it into 8 kg. water, bring the solution to 25 ° C and pour it into melted and cooled to 50 ° C lard (the lard should be unsalted and take 12 kg 800 g of it for the specified amount of water and salt). The resulting liquid mixture is thoroughly stirred until the entire mass becomes completely homogeneous, after which it is poured into wooden boxes, well wrapped in felt, and placed in a warm, dry place. After 4-5 days, the mass hardens and the soap is ready.

To get good toilet soap For every 100 g of pork fat, take 5-20 g of coconut oil. It is necessary to ensure that the resulting soap is neutral. For this purpose, it is salted several times and then boiled. After the last salting, boiling continues until the sample taken with a glass rod on the plate turns out to be completely satisfactory, that is, when the mass is squeezed between the fingers, hard plates are obtained that should not break.

The dyes used to tint toilet soap can be very diverse. The main conditions that they must satisfy: be strong enough, mix well with soap and

do not have a harmful effect on the skin.

The red color for transparent soap is obtained using fuchsin and eosin; For opaque soap, cinnabar and red lead are used.

The yellow color of the soap is given by turmeric extract and picric acid.

To obtain green soap, green aniline or chrome green dye is used.

The brown color of soap comes from light or dark brown aniline dye or burnt sugar. In the manufacture of toilet soap, perfumery plays a particularly important role. The fact is that the fragrance should not only be pleasant, but should also retain its smell for a long time and even, if possible, improve when the soap lies and dries. Therefore, when perfuming, the first question is at what temperature the soap should be perfumed. Then, what is the effect of alkalis on the odorous substances used. And, finally, are these odorous substances well preserved in alkalis?

Good soap has a pleasant, unobtrusive smell due to the perfume additives introduced into it - fragrances. Special varieties of soap also include antiseptics (triclosan, chlorhexidine, salicylic acid) and biologically active substances, including those obtained from natural raw materials of medicinal plants.

Technology for making soap at home

In order to prepare soap at home, you must follow the following sequence of operations:

1. Fill a glass ½ full with water, place it on a tripod with a metal mesh and boil the water.

2. Pour castor oil and sodium hydroxide solution into an evaporating dish.

3. Place the evaporation cup on a glass of boiling water and heat for 10-15 minutes, stirring its contents with a glass rod.

4. Add saturated sodium chloride solution and stir.

5. Cool the cup with the contents.

6. Using a spatula, collect the soap and form it into two pieces the size of a grain of rice.

You can flavor the resulting soap with the help of plant extracts, using for this purpose the following plants: currant leaves, pine needles, calendula flowers, chamomile.

Areas of application of soap.

In addition to using soap as a detergent, it is widely used in bleaching fabrics, in the production of cosmetics, and for the manufacture of polishing compounds for water-based paints.

In everyday life, not to mention industry, various items and objects are subjected to the washing process. Pollutants come in a wide variety of forms, but most often they are poorly soluble or insoluble in water. Such substances, as a rule, are hydrophobic, since they are not wetted by water and do not interact with water. Therefore, various detergents are needed.

If we try to define this process, then washing can be called cleaning a contaminated surface with a liquid containing a detergent or a system of detergents. Water is mainly used as a liquid in everyday life. A good cleaning system should perform a dual function: remove dirt from the surface being cleaned and transfer it into an aqueous solution. This means that the detergent must also have a dual function: the ability to interact with the pollutant and the ability to transfer it into water or an aqueous solution. Therefore, a detergent molecule must have hydrophobic and hydrophilic parts. "Phobos" in Greek means fear. Fear. So hydrophobic means “afraid of, avoiding water.” “Phileo” in Greek means “love”, hydrophilic means loving, holding water. The hydrophobic part of the detergent molecule has the ability to interact with the surface of the hydrophobic contaminant. The hydrophilic portion of the detergent interacts with the water, penetrates the water, and carries with it the contaminant particle attached to the hydrophobic end.

Thus, detergents must have the ability to be adsorbed on the boundary surface, that is, they must have surfactants.

Salts of heavy carboxylic acids, for example CH3(CH2)14COONa, are typical surfactants. They contain a hydrophilic part (in this case, a carboxyl group) and a hydrophobic part (hydrocarbon radical).

Practical work

"Secrets of Soap Making"

Purpose: to study the process of saponification of higher fatty acids.

Having studied the theory, we will try to make soap in practice by cooking it in an artisanal way.

To make our soap safe for health, we will use natural raw materials.

We use the following equipment and raw materials:

· round flat-bottomed flask with a capacity of 1000 cm3,

· glass rod,

· tripod with accessories,

· alcohol lamp,

· porcelain glasses with a capacity of 500 cm3 and 200 cm3,

· porcelain spoon,

· tweezers,

· technical scales,

· glass glass with a capacity of 100 cm3,

· beef fat 70g,

pork lard 30g,

· ethyl alcohol 20 ml,

· Na2CO3 solution,

NaCl solution 20% 200 ml,

· 2 drops eucalyptus oil, aromatic substance dissolved in alcohol, scraps of fabric measuring 5X5 cm,

· mold for pressing soap.

Progress: And so let's start with getting high quality sound soap.

· Weigh 70 g of beef and 30 g of pork fat on a technical scale and place it in a 1000 cm3 flask mounted on a tripod.

· Prepare a solution of soda ash Na2CO3 (25 g Na2CO3+ 30 ml H2O).

· Pour 20 ml of ethyl alcohol into the flask. It will help dissolve and contact non-polar fat in polar alkali.

· Carefully pour in the prepared Na2CO3 alkali solution while heating and stirring.

· The saponification reaction of fat occurs only when heated. A sign of a reaction is the appearance of soap.

· Pour a 20% NaCl solution into the resulting mixture and heat the mixture again until the soap is completely separated.

· Unlike hot water, soap is almost insoluble in a solution of table salt. Therefore, when salted out, it separates from the solution and floats up.

· Let the mixture cool a little, collect the released layer of soap with a spoon onto a piece of cloth, wrap it (you need to work with rubber gloves!) and rinse in cold water.

· After squeezing it lightly, transfer it to another piece of fabric.

· Let's check the pH of the soap (the normal pH level is 6-7). Ours was higher, so we salted the soap again and washed it with water.

Our second experience will be to obtain toilet soap.

To obtain toilet soap, kernel soap is crushed and kneaded. Then add 2 drops of eucalyptus oil to the soap (essential oil, liquid, yellow, antiseptic and anti-inflammatory).

Studying the properties of soap

To study the properties of soap, it is necessary to conduct a series of experiments confirming its cleaning properties. To do this you should:

1. Pour 5 ml of distilled water into one test tube, the same amount of tap water into another, place a piece of soap in each.

2. Close the stoppers and shake both test tubes simultaneously for several seconds.

3. Place the test tubes in a rack and use a stopwatch to determine how long the foam remains in each test tube. In a test tube with distilled water, the foam lasts for 30 seconds, and with tap water for 10 seconds.

4. Note the type of contents of each test tube. The solution became cloudy from soap in two test tubes.

5. Using universal indicator paper, determine the acidity of the soap solution. The soap solution has a slightly alkaline environment.

6. The presence of glycerol in the reaction mixture can be detected using a qualitative reaction to polyhydric alcohols, i.e., by adding freshly prepared copper hydroxide. When copper hydroxide was added to the test tubes, the solution turned bright blue.

Conclusions:

· soap made at home smells pleasant, foams and lathers well, has antibacterial properties and is environmentally friendly;

· soap has a slightly alkaline reaction;

· gives a characteristic reaction to glycerol content.

Literature:

1. Aleksinsky experiments in chemistry - M., 1995.

2. Bogdanova. Laboratory works. 8 – 11 grades: Textbook. manual for educational institutions. - M.: Astrel": AST", 2001. - 112 p.: ill.

3. Great Soviet Encyclopedia (in 30 volumes). Ch. ed. . Ed. 3rd M., “Soviet Encyclopedia”. 1972.T.17 Morshansk - Myatlik. 1974.616pp.

4. Grosse, Chemistry for the curious - M., 1993.

5. Zinoviev Zhirov – M., 1990

6. Selemeneva in everyday life - http:// festival. 1 *****

7. Tobbin for soap production - M 1991

8. – Chemistry at leisure – M., 1996.

9. Shabanova student activities – http:// festival. 1 *****

10. Shcherbakova projects: organization of activities in chemistry - http:// festival. 1 *****

11. I explore the world: Children's encyclopedia: Chemistry / Author. – comp. ; Artist , . – M.: “AST Publishing House”; 1999. – 448 p.

Review of the special course « Methods for solving calculation problems in chemistry for students in grades 10-11» chemistry teachers Kulikova N, S.

Municipal educational institution "Umyganskaya secondary school",With. Umygan, Tulunsky district

This work is part of the program for the study of organic chemistry on the topic “Fats”, an elective course “Chemistry in everyday life”.

Valentina decided to study this topic on her own, as she was interested in whether soap could be made at home and whether it would turn out the same as what is sold in stores.

In this project, the teacher already acts as a consultant. Knowing this, it can be noted that this work is a continuation of the continuous process of developing cognitive interests, research skills, developing the ability to observe and analyze what is happening during experiments, the development of practical skills and recording the results of observation, and then drawing the necessary conclusions based on the results.

The work presents basic information about the origin of soap, the history of soap making, composition, properties, classification of soap, raw materials for its production and areas of application.

Studying the theoretical part makes it possible to learn how to make soap at home so that it is an environmentally friendly product. All these aspects are reflected in this research project.

And the choice of this topic contributes to the development of practical skills and the development of creativity.

The main principle of completing the work is the student’s personal interest in acquiring chemical knowledge. Valentina developed such an interest due to the originality of the project idea and the fascinating nature of the results obtained.

All sections of the project are interconnected and have continuity at each stage.

The work implements the principle of developmental education, aimed at obtaining new knowledge through research activities, and develops practical research skills.

But the most important outcome of this project is that it promotes curiosity, inquiry, and a sustained interest in chemistry.

Project Manager.

Definition

Soap- liquid or solid products containing surfactants, in combination with water, used for cleansing and skin care (toilet soap, shampoos, gels), or as a household chemical - detergent (laundry soap).

Chemical composition of soap

From a chemical composition point of view:

solid soaps- mixture of soluble sodium salts higher fatty (saturated and unsaturated) acids;

liquid soaps- mixture of soluble potassium or ammonium salts the same acids

One of the options for the chemical composition of solid soap is $C_(17)H_(35)COONa$, liquid soap is $CC_(17)HH_(35)COOK$. Fatty acids from which soap is made include:

• stearic(octadecanoic acid) - $C_(17)H_(35)COOH$, solid, monobasic saturated carboxylic acid, one of the most common fatty acids in nature, included in the form of glycerides in the composition lipids, primarily triglycerides of fats of animal origin (in lamb fat up to ~30%, in vegetable fat (palm oil) - up to 10%).
• palmitic(hexadecanoic acid) - $C_(15)H_(31)COOH$, the most common solid monobasic saturated carboxylic acid (fatty acid) in nature, is part of the glycerides of most animal fats and vegetable oils (butter contains 25%, lard - 30%), many vegetable fats ((palm, pumpkin, cottonseed oils, Brazil nut oil, cocoa, etc.);
• myristic (tetradecanoic acid) - $C_(13)H_(27)COOH$ - monobasic saturated carboxylic acid, found in nature as a triglyceride in almond, palm, coconut, cottonseed and other vegetable oils
• lauric(dodecanoic acid) - $C_(11)H_(23)COOH$ - monobasic saturated carboxylic acid, as well as myristic acid, is found in many vegetable oils of southern cultures: palm, coconut, plum kernel oil, tucuma palm oil, etc.
• oleic(cis-9-octadecenoic acid) - $CH_3(CH_2)_7-CH=CH-(CH_2)_7COOH$ or general formula $C_(17)H_(33)COOH$ - liquid monobasic monounsaturated fatty acid, belongs to the omega group -9 unsaturated fatty acids, found in large quantities in animal fats, especially fish oil, as well as in many vegetable oils - olive. sunflower, peanut, almond, etc.

Additionally, soap may contain other substances that have a detergent effect, as well as flavors and dyes. Often, to improve consumer properties, glycerin, talc, and antiseptics are added to soap.

Methods for making soap

All methods for producing soap are based on the reaction of alkaline hydrolysis of fats (animal or vegetable):

Making solid soap

To prepare solid soap, you need to take about 30 g of lard and about 70 g of beef fat. Melt all this, and when the fat melts, add 25 g of solid alkali NaOH and 40 ml of water. The lye must be heated before adding.

Attention! You need to work with alkali carefully so that its splashes do not get on your skin.

Continue heating for half an hour over low heat, remembering to stir (it is better to stir with a glass rod). As the water boils, you need to add preheated water to the mixture.

To separate (salt out) the resulting soap from the solution, you can use a solution of table salt (NaCl). To prepare it, you need to dissolve 20 g of NaCl salt in 100 ml of water. After adding salt, continue heating the mixture. As a result of salting out, soap flakes appear on the surface of the solution. After cooling, you need to collect the flakes that appear from the surface of the solution with a spoon and squeeze them out using a cloth or gauze. To prevent alkali residue from getting on your hands, it is best to carry out this operation with rubber gloves.

The resulting mass should be washed with a small amount of cold water and, to obtain a pleasant aroma, you can add an alcohol solution of a fragrant substance (for example, perfume). You can also add coloring and antiseptic substances. Then knead the whole mass and, with slight heating, form the desired shape.

When producing toilet soap on an industrial scale, vegetable fats, rather than animal fats, are mainly used. How many different fats there are, so many different types of soap can be made. For example, liquid soaps (with the exception of olive oil) are predominantly obtained from vegetable oils, but unlike solid soap, liquid soap is not separated by “salting out”.

Preparation of liquid soap

The preparation of liquid soap, as well as the preparation of solid soap, is carried out by alkaline hydrolysis, but, unlike the previous method, you need to use a solution of potassium hydroxide (KOH). Instead of animal fat, you can take vegetable oil with the addition of 30 g of potassium alkali (KOH) and 40 ml of water.

Attention! Just like when preparing solid soap, alkali is a caustic substance; it is better to work with gloves.

All operations are carried out similarly to the first method. However, instead of salting it out, you need to let the solution cool, stirring constantly. This creates a mixture of soap and water, plus a small amount of unreacted substances called “glue soap.” There is no need to separate the mixture. because it has cleaning properties.

SURFACTANTS (SURFACTANTS)

Definition

Surfactants (surfactants) are chemical compounds that, concentrating at the interface between thermodynamic phases, cause a decrease in surface tension.

The main quantitative characteristic of a surfactant is surface activity - the ability of a substance to reduce surface tension at the interface.

Surfactants are organic compounds containing polar part, that is hydrophilic component(functional groups of acids and their salts -OH, -COO(H)Na, -$OSO_2O(H)Na$, -$SO_3(H)Na$) and non-polar(hydrocarbon) part, that is hydrophobic component.

As already stated, soaps are surfactants. In addition to various types of soap, surfactants also include various synthetic detergents (SMC), as well as alcohols, carboxylic acids, amines, etc.

On based on the chemical nature of molecules,Surfactants are divided into four main classes: anionic, cationic, nonionic and amphoteric.

1. Anionic surfactants contain one or more polar groups in the molecule and dissociate in an aqueous solution to form chains of anions that determine their surface activity. The hydrophobic part of the molecule is usually represented by saturated or unsaturated aliphatic chains or alkylaromatic radicals. In total, six groups of anionic surfactants are distinguished. The most common anionic surfactants are alkyl sulfates and alkylaryl sulfonates. These substances are low toxic, do not irritate human skin and undergo satisfactory biological decomposition in water bodies, with the exception of alkylaryl sulfonates with a branched alkyl chain. Anionic surfactants are used for the production of washing powders and cleaning products.

2. Cationic surfactants dissociate in aqueous solution to form a surfactant cation with a long hydrophobic chain and an anion, usually a halide, sometimes a sulfuric or phosphoric acid anion. Nitrogen-containing compounds predominate among cationic surfactants. Cationic surfactants reduce surface tension less than anionic surfactants, but they can interact chemically with the surface of the adsorbent, for example with bacterial cellular proteins, causing a bactericidal effect. Cationic surfactants reduce surface tension less than anionic surfactants, but they can be used to soften fabrics. Cationic surfactants are also included in washing powders and cleaning products, but in addition, shampoos, shower gels and fabric softeners are prepared on their basis.

3. Nonionic surfactants do not dissociate into ions in water. Their solubility is due to the presence in the molecules of hydrophilic ether and hydroxyl groups, most often the polyethylene glycol chain. A characteristic feature of nonionic surfactants is their liquid state and low foaming in aqueous solutions. Such surfactants clean polyester and polyamide fibers well.

4. Amphoteric (ampholytic) surfactants contain in the molecule a hydrophilic radical and a hydrophobic part that can be an acceptor or donor of a proton, depending on the pH of the solution. Typically these surfactants include one or more basic and acidic groups. Depending on the pH value, they exhibit the properties of cationic or anionic surfactants. From the group of amphoteric surfactants, betaine derivatives (for example, cocaminopropyl betaine) are most often used. In combination with anionic surfactants, they improve foaming ability and increase the safety of detergents. These derivatives are obtained from natural raw materials, so they are quite expensive components. Amphoteric and nonionic surfactants are used in the production of delicate detergents - shampoos, gels, and cleansers.

INFLUENCE OF PASTERANTS ON HUMANS AND ENVIRONMENTAL COMPONENTS

Aqueous solutions of surfactants in greater or lesser concentrations enter water bodies with industrial and domestic wastewater. Much attention is paid to the treatment of wastewater from surfactants, since due to the low rate of decomposition, the negative impact on plant and animal organisms is difficult to predict. Wastewater containing hydrolysis products of polyphosphate surfactants can cause intensive plant growth, which leads to pollution of previously clean water bodies: as plants die, they begin to rot, and the content of dissolved oxygen in the water decreases, which in turn worsens the conditions for the existence of other living forms in the water. body of water

Like any environment in the biosphere, a body of water has its own protective powers and has the ability to self-purify. Self-purification occurs due to dilution, settling of particles to the bottom and formation of deposits, decomposition of organic substances to ammonia and its salts due to the action of microorganisms. The great difficulty of self-healing of water bodies after exposure to surfactants is that surfactants are most often present in the form of a mixture of individual homologs and isomers, each of which exhibits individual properties when interacting with water and bottom sediments, and the mechanism of their biochemical decomposition is also different. Studies of the properties of surfactant mixtures have shown that in concentrations close to the threshold, these substances have the effect of summing up their harmful effects.

Surfactants are divided into those that are quickly destroyed in the environment and those that are not destroyed and can accumulate in organisms in unacceptable concentrations. One of the main negative effects of surfactants in the environment is a decrease in surface tension. In water bodies, changes in surface tension lead to a decrease in oxygen concentration in the water mass, which causes an increase in the biomass of blue-green and brown algae and the death of fish and other aquatic organisms.

Only a few surfactants are considered safe (alkyl polyglucosides), since their breakdown products are carbohydrates. However, when surfactants are adsorbed on the surface of particles (silt, sand), the rate of their destruction decreases many times over. Therefore, under normal conditions, they can release (desorb) heavy metal ions held by these particles, and thereby increase the risk of these substances entering the human body.

Surfactants can enter the human body in different ways - with food, water, through the skin. Surfactant components can cause allergic reactions, including severe complications.

Before the invention of soap, fat and dirt were removed from the skin using ash and fine river sand. The Egyptians washed their faces with a paste based on beeswax mixed with water. In Ancient Rome, finely ground chalk, pumice, and ash were used when washing. Apparently, the Romans were not bothered by the fact that during such ablutions, along with the dirt, it was possible to “scrape off” part of the skin itself. The credit for the invention of soap probably belongs to the Gallic tribes. According to Pliny the Elder, the Gauls made an ointment from the tallow and ash of the beech tree, which was used to dye hair and treat skin diseases. And in the 2nd century they began to use it as a detergent.

The Christian religion considered washing the body a “sinful” act. Many "saints" were known only for not washing their entire lives. But people have long noticed the harm and health hazards of skin pollution. Already in the 18th century, soap making was established in Rus', and in a number of European countries even earlier.

The technology for making soap from animal fats has evolved over many centuries. First, a fat mixture is prepared, which is melted and saponified - boiled with alkali. To hydrolyze fat in an alkaline environment, take a little rendered lard, about 10 ml of ethyl alcohol and 10 ml of alkali solution. Table salt is also added here and the resulting mixture is heated. This produces soap and glycerin. Salt is added to precipitate glycerin and impurities. Two layers are formed in the soap mass - the core (pure soap) and the soapy lye .

Soap is also produced industrially.

Saponification of fats can also occur in the presence of sulfuric acid (acid saponification). This produces glycerol and higher carboxylic acids. The latter are converted into soaps by the action of alkali or soda. The starting materials for soap production are vegetable oils (sunflower, cottonseed, etc.), animal fats, as well as sodium hydroxide or soda ash. Vegetable oils are first hydrogenated, i.e. they are converted into solid fats. Fat substitutes are also used - synthetic carboxylic fatty acids with a large molecular weight. Soap production requires large quantities of raw materials, so the task is to obtain soap from non-food products. The carboxylic acids necessary for soap production are obtained by oxidation of paraffin. By neutralizing acids containing from 9 to 15 carbon atoms per molecule, toilet soap is obtained, and from acids containing from 16 to 20 carbon atoms, laundry soap and soap for technical purposes are obtained.

Soap composition

Conventional soaps consist primarily of a mixture of salts of palmitic, stearic and oleic acids. Sodium salts form solid soaps, potassium salts form liquid soaps.

Soap - sodium or potassium salts of higher carboxylic acids,
obtained as a result of hydrolysis of fats in an alkaline environment

The structure of soap can be described by the general formula:

R – COOM

where R is a hydrocarbon radical, M is a metal.

Benefits of soap:

a) simplicity and ease of use;

b) removes sebum well

c) has antiseptic properties

Disadvantages of soap and their elimination:

flaws	solutions
1. Poor cleaning ability in hard water containing soluble calcium and magnesium salts. Since in this case, water-insoluble salts of higher carboxylic acids of calcium and magnesium precipitate. Those. this requires a large consumption of soap.	1. Complexing substances that help soften water are added to the soap (sodium salts of ethylenediamine-tetraacetic acid - EDTA, EDTA, DTPA).
2. In aqueous solutions, soap is partially hydrolyzed, i.e. interacts with water. This produces a certain amount of alkali, which helps break down sebum and remove it. Potassium salts of higher carboxylic acids (i.e. liquid soap) are better soluble in water and therefore have a stronger cleaning effect. But at the same time it has a harmful effect on the skin of the hands and body. This is due to the fact that the thinnest upper layer of the skin has a slightly acidic reaction (pH = 5.5) and thereby prevents pathogenic bacteria from penetrating into the deeper layers of the skin. Washing with soap leads to a violation of the pH (the reaction becomes slightly alkaline), the skin pores open, which leads to a decrease in the natural protective reaction. If you use soap too often, your skin becomes dry and sometimes becomes inflamed.	2. To reduce this negative impact, modern soaps add: - weak acids (citric acid, boric acid, benzoic acid, etc.), which normalize pH - creams, glycerin, petroleum jelly, palm oil, coconut oil, diethanolamides of coconut and palm oils, etc. to soften the skin and prevent bacteria from entering the skin pores.

Experiment:

Take a cup of water. Place a match there so that it floats on the surface. Touch the pointed end of the soap to the surface of the water on the side of the match. The match moves away from the soap. This happens because the surface tension of water is greater than that of soap. Different forces act on the match from different directions - it moves away from the greater force of surface tension. The surface layer of distilled water is in a tense state like an elastic film. When soap and some other water-soluble substances are added, the surface tension of water decreases. Soap and other detergents are classified as surfactants (surfactants). They reduce the surface tension of water, thereby enhancing the cleaning properties of water.

Soap structure- sodium stearate.

Video experiment “Isolation of free fatty acids from soap”

The sodium stearate molecule has a long non-polar hydrocarbon radical (indicated by a wavy line) and a small polar part:

The surfactant molecules on the boundary surface are arranged in such a way that the hydrophilic groups of carboxyl anions are directed into the water, and the hydrophobic hydrocarbon groups are pushed out of it. As a result, the surface of the water is covered with a palisade of surfactant molecules. Such a water surface has lower surface tension, which facilitates rapid and complete wetting of contaminated surfaces. By reducing the tension surface of water, we increase its wetting ability.

SMS (synthetic detergents) – sodium salts of esters of higher alcohols and sulfuric acid:

R – CH 2 – O – SO 2 – ONa

Both synthetic soap and soap made from fats do not clean well in hard water. Therefore, along with soap from synthetic acids, detergents are produced from other types of raw materials, for example, from alkyl sulfates - salts of esters of higher alcohols and sulfuric acid. In general, the formation of such salts can be represented by the equations:

These salts contain from 12 to 14 carbon atoms per molecule and have very good cleaning properties. Calcium and magnesium salts are soluble in water, and therefore such soaps can be washed in hard water. Alkyl sulfates are found in many laundry detergents.

Synthetic detergents release hundreds of thousands of tons of food raw materials - vegetable oils and fats.

Experiment:

You can compare soaps and SMS (washing powder) by checking with indicators what environment is typical for our detergents.

When litmus is added to a soap solution and to an SMS solution, it becomes blue, and phenolphthalein becomes crimson, that is, the reaction of the medium is alkaline. By the way, if the detergent is intended for washing cotton fabrics, then the reaction of the medium should be alkaline, and if for silk and wool fabrics, it should be neutral.

What happens to soap and SMS in hard water?

Add the soap solution to one test tube and the SMS solution to the other, shake them up. What are you observing? Add calcium chloride to the same test tubes and shake the contents of the test tubes. What are you observing now? The SMS solution foams, and insoluble salts form in the soap solution:

2C 17 H 35 COO – + Ca 2+ = Ca(C 17 H 35 COO) 2 ↓

SMCs form soluble calcium salts, which also have surface-active properties.

Using excessive amounts of these products leads to environmental pollution.

Many surfactants are difficult to biodegrade. When wastewater enters rivers and lakes, it pollutes the environment. As a result, whole mountains of foam are formed in sewer pipes, rivers, lakes, where industrial and domestic wastewater ends up. The use of some surfactants leads to the death of all living inhabitants in the water. Why does a soap solution quickly decompose when it gets into a river or lake, but some surfactants do not? The fact is that soaps made from fats contain unbranched hydrocarbon chains that are destroyed by bacteria. At the same time, some SMCs contain alkyl sulfates or alkyl (aryl) sulfonates with hydrocarbon chains having a branched or aromatic structure. Bacteria cannot “digest” such compounds. Therefore, when creating new surfactants, it is necessary to take into account not only their effectiveness, but also their ability to biodegrade - to be destroyed by certain types of microorganisms.