Nomenclature and isomeria. Soaps and detergents
The main part of the fats of animal and vegetable origin is the esters of trochatic alcohol - glycerin and fatty acids, called glycerides(acyl glycerides). Fatty acids are part of not only glycerides, but also in most other lipids.
The variety of physical and chemical properties of natural fats is due to the chemical composition of glyceride fatty acids. Fat triglycerides consists of various fatty acids. In this case, depending on the type of animal or plants, the fats are obtained, the fatty acid composition of triglycerides is different.
The glycerides of fats and oils are mainly highly molecular fatty acids with the number of carbon atoms 16,18, 20.22 and higher, low molecular weight with the number of carbon atoms 4, 6 and 8 (oil, kapron and capric acid). The number of sedicated acids reaches 170, but some of them are not yet sufficiently studied and the information about them is very limited.
The composition of natural fat includes saturated (limit) and unsaturated (unsaturated) fatty acids. Unsaturated fatty acids may contain double and triple bonds. The latter in natural fats are very rare. As a rule, only single-axis carboxylic acids with an even number of carbon atoms are contained in natural fats. Buses are highlighted in small quantities in some waxes and in fats undergoing oxidizing agents. The overwhelming part of fatty acids in fats has an open chain of carbon atoms. Acid with a branched chain of carbon atoms in fats is rare. Such acids are part of some waxes.
Fatty acids of natural fats are liquid or solid, but low-melting substances. High molecular weights are solid, most unsaturated fatty acids of normal structure are liquid substances, and their positional and geometric isomers are solid. The relative density of fatty acids is less than the unit and they are practically insoluble in water (with the exception of low molecular weight). In organic solvents (alcohol, ethyl and petroleum ether, benzene, servo-carbon, etc.) they dissolve, but with an increase in the molecular weight solubility of fatty acids decreases. Oxycycles are practically insoluble in petroleum ether and cold gasoline, but soluble in ethyl ether and alcohol.
Of great importance for oil refining and in soaps, the reaction of the interaction of caustic alkali and fatty acids is the neutralization reaction. When sodium carbon dioxide or potassium carbon dioxide is also an alkaline salt or soap with carbon dioxide. This reaction occurs in the process of cooking soap with the so-called carbonate washing of fatty acids.
Fatty acids of natural fats for rare exceptions belong to the class of monosular aliphatic carboxylic acids having a general formula for RCOOH. In this formula, R is a hydrocarbon radical that can be saturated, unsaturated (varying degrees of unsaturation) or to contain a group - it is, coxy of carboxyl. On the basis of X-ray structural analysis, it is currently established that the centers of carbon atoms in the radicals chains of fatty acids are not spatially located in a straight line, but zigzag. At the same time, the centers of all carbon atoms of limit acids are laid on two parallel straight lines.
The length of the hydrocarbon radical of fatty acid affects the solubility of them in organic solvents. For example, solubility at 20 ° C in 100 g of anhydrous ethyl alcohol with lauryic acid 105 g, Miristinova - 23.9 g, and Stearinova - 2.25 g.
Isomerius of fatty acids.Under isomeria, the existence of several chemical compounds of the same composition and the same molecular weight, but differing in physical and chemical properties. Two main types of isomerism are known: structural and spatial (stereoisomeria).
Structural isomersdisturbed by the structure of the carbon chain, the location of double bonds and the location of functional groups.
An example of structural isomers are connections:
a) various in the structure of the carbon chain: Normal oil acid CH 3 CH 2 CH 2 coxy; Isomaslane acid
b) various in the location of double bonds: oleic acid CH 3 (CH 2) 7 CH \u003d CH (CH 2) 7 coxy; Petyrelinic acid CH 3 (CH 2) 10 CH \u003d CH (CH 2) 4 coxy; Vacucene acid CH 3 (CH 2) 5 CH \u003d CH (CH 2) 8 COOH.
Spatial isomersor stereoisomers, with the same structure, differ in the location of atoms in space. This type of isomers includes geometric (cis and transisomers) and optical. An example of spatial isomers are:
a) geometric isomers: oleic acid having cisform
elaidinic acid having transform
b) optical isomers:
milk Acid CH 3 Snonson;
glycerin Aldehyde CH 3 ONSNONSO;
ricinoleic acid SNZ (CH 2) 5 CNNSH 2 CH \u003d CH (CH 2) 7 Soam.
In all these optical isomers, asymmetric (active) carbon is marked with an asterisk.
Optical isomers rotate the plane of the polarization of light to the same angle in opposite directions. Most of the natural fatty acids of the optical isomerism has no.
In natural fats, non-oxidative processes, unsaturated fatty acids are mainly a circconfiguration. Geometric cis- and transzomers of unsaturated fatty acids differ significantly at the melting point. Cysisometers melt at a lower temperature than transizometers. This brightly illustrates the cis-transpreation reaction with liquid oleic acid into solid elaidinic acid (melting point 46.5 ° C). At the same time, fat solidifies.
The same transformation occurs with the erukic acid, which moves into solid transzymerorsidine acid (melting point 61.9 ° C), as well as a ricinoleic acid, turning into a transzymeer - racinelaidic acid (melting point 53 ° C).
Polyunsaturated fatty acids (linoleic, linolenic) with this consistency reaction do not change.
The following main homological groups of fatty acids are found in natural fats that are not subject to oxidizing processes:
1. Saturated (limit) monophonic acids.
2. Unsaturated (unforeseen) monophonic acids with one, two, three, four and five double bonds.
3. Saturated (limit) hydroxy acids.
4. Unsaturated (unforeseen) hydroxy acids with one double bond.
5. Two-axis saturated (limit) acids.
6. Cyclic acids.
The esters can be considered as derived acids in which the hydrogen atom in the carboxyl group is substituted for a hydrocarbon radical:
Nomenclature.
The esters are called across the acids and alcohols, the remains of which are involved in their formation, for example, n-co-o-CH3 - methyl formate, or Methyl ether of formic acid; - ethyl acetate, or ethyl acetic ester.
Methods for obtaining.
1. The interaction of alcohols and acids (esterification reaction):
2. The interaction of chloranhydrides of acids and alcohols (or alkali metal alcoholites):
Physical properties.
Esters of lower acids and alcohols - liquid lighter than water, with a pleasant smell. In water soluble only esters with the smallest number of carbon atoms. In alcohol and disetile ester, soluble esters are well.
Chemical properties.
1. Hydrolysis of esters is the most important reaction of this group of substances. Hydrolysis under the action of water is a reversible reaction. Alkali is used to dismiss the equilibrium:
2. The restoration of the esters of hydrogen leads to the formation of two alcohols:
3. Under the action of ammonia, the esters are converted into amides acids:
Fats. Fats are mixtures of esters formed by trihatic alcohol glycerin and higher fatty acids. General formula of fats:
where R is the radicals of higher fatty acids.
Most often, fats include palmitic and stearin and unsaturated acids oleic and linoleic acids.
Getting fat.
Currently, it is practical significance only to obtain fats from natural sources of animal or plant origin.
Physical properties.
Fats formed by extreme acids - solids, and unsaturated - liquid. Everything is very poorly soluble in water, well soluble in diethyl ether.
Chemical properties.
1. Hydrolysis, or oil washer due to water (reversible) or alkalis (irreversible):
With alkaline hydrolysis, the salts of higher fatty acids are formed, called soaps.
2. The hydrogenation of fat is the process of the addition of hydrogen to the residues of unsaturated acids included in the fat. At the same time, the residues of non-precious acids are transferred to the remnants of limit acids, and the fats from the liquid turn into solid.
Of the most important foodstuffs - proteins, fats and carbohydrates - fats have the greatest reserve of energy.
Chapter 30. Essential Esters. Fat.
Soaps and detergents. Sodium and potassium salts of higher fatty acids are called soaps, because They have good detergent properties. Sodium salts make up the basis of solid soap, while potassium salts are liquid. They are obtained by boiling an animal of salla or vegetable oil with sodium hydroxide or potassium - hence the old name of alkaline hydrolysis of fats - "washed". Cleansing (detergents) of soap properties are explained by the wetting capacity of soluble salts of higher fatty acids, i.e. Soap anions have affinity, both fatty pollution and water. Anionic carboxygroup has affinity for water: it is hydrophilin. The hydrocarbon and fatty acid chain has affinity for greasy pollution. It is a hydrophobic end of the soap molecule. This end dissolves in a drop of dirt, resulting in its transformation and transformation into a micelle. The removal of "foamy" micelles from a contaminated surface is achieved by washing with water.
In the so-called toughwater containing ions Ca 2+ and Mg 2+ decreases the detergent of soap, since, interacting with calcium and magnesium ions, soaps form insoluble calcium and magnesium salts, for example:
As a result, the soap forms flakes instead of foam on the surface of the water and is consumed useless. This lack is deprived synthetic detergents(detergents), representsby himself sodium saltsvalid suldokislotgeneral formula:
Common synthetic detergents (detergents) are alkylbenzenesulfonates:
True, the ubiquitous use of synthetic detergents (washing powders) creates its problems. Typical washing powder contains approximately 70% synthetic detergent and approximately 30% of inorganic phosphates. Phosphates remove soluble calcium salts. Unfortunately, these phosphates fall into wastewater, which are reset in streams, rivers, lakes or oceans. Phosphates are a nutrient medium for certain algae. This leads to a strong generation of cyanobacteria, especially in closed reservoirs, for example, in lakes.
Among the functional derivatives of carboxylic acids, a special place occupy essentials- Compounds representing carboxylic acids in which hydrogen atom in the carboxyl group is replaced by a hydrocarbon radical. General formula for esters
The sophisticated ether molecule consists of an acid residue (1) and alcohol residue (2).
The names of the esters are produced from the name of the hydrocarbon radical and the name of the acid, in which instead of the end of "--spa acid", the "AT" suffix is \u200b\u200bused, for example:
Often, esters are called the residues of acids and alcohols from which they consist. Thus, the complex esters considered above may be called: acetic ether, crotonomethyl ether.
For esters, three types of isomeria are characteristic: 1. Isomeria carbon chain,it begins at an acidic residue with butanic acid, on an alcohol residue - from propyl alcohol, for example:
2. Isomeria positions of the ester group -Co-o- This type of isomerism begins the poverty ether, in the molecules of which are contained at least 4 carbon atoms, for example:
3. Interclative isomeria,eg:
For esters containing unsaturated acid or unintended alcohol, two more types of isomeria are possible: isomerism of the position of a multiple communication and cis-transisomeria .
Nomenclature and isomeria
Among the functional derivatives of carboxylic acids, a special place occupy essentials- Compounds representing carboxylic acids in which hydrogen atom in the carboxyl group is replaced by a hydrocarbon radical. General formula for esters
The sophisticated ether molecule consists of an acid residue (1) and alcohol residue (2).
The names of the esters are produced from the name of the hydrocarbon radical and the name of the acid, in which instead of the end of "--spa acid", the "AT" suffix is \u200b\u200bused, for example:
Often, esters are called the residues of acids and alcohols from which they consist. Thus, the complex esters considered above may be called: acetic ether, crotonomethyl ether.
For esters, three types of isomeria are characteristic: 1. Isomeria carbon chain,it begins at an acidic residue with butanic acid, on an alcohol residue - from propyl alcohol, for example:
2. Isomeria positions of the ester group -Co-o- This type of isomerism begins the poverty ether, in the molecules of which are contained at least 4 carbon atoms, for example:
3. Interclative isomeria,eg:
For esters containing unsaturated acid or unintended alcohol, two more types of isomeria are possible: isomerism of the position of a multiple communication and cis-transisomeria .
Physical properties
The esters of lower carboxylic acids and alcohols are volatile, low-soluble or practically insoluble liquid water. Many of them have nice smell.For example, HCOOC 2 H 5 - the smell of Roma, HCOOC 5 H 11 - cherries, HCOOC 5 H 11 - Plum, CH 3 SOP 5 H 11 - Pear - pears, with 3 H 7 SAO 2 H 5 - apricot, C 3 H 7 SOSO 4 H 9 - Pineapple, with 4 H 9 SAOS 5N 11 - Apples, etc
The esters have, as a rule, have a lower boiling point than the corresponding acids. For example, stearin acid boils at 232 ° C, and methylstearate - at 215 ° C. This is explained by the fact that there are no hydrogen bonds between molecules of esters.
Esters of higher fatty acids and alcohols - wax substances, do not smell, are not soluble in water, well soluble in organic solvents. For example, beeswax is mainly minecyl palmitate (from 15 H 31 COOC 31 H 63)
Chemical properties
1. Reaction of hydrolysis or washed.
Reaction esterification is reversibletherefore, in the presence of acids, the reverse reaction will flow, called hydrolysis, as a result of which the source fatty acids and alcohol are formed:
The hydrolysis reaction accelerates under the action of alkalis; In this case, the hydrolysis is irreversible:
since the resulting carboxylic acid with alkali forms salt:
2. Connection reaction.
Esters that have in their composition unsaturated acid or alcohol are capable of accession reactions. For example, with catalytic hydrogenation, they attach hydrogen.
3. Recovery reaction.
The restoration of esters with hydrogen leads to the formation of two alcohols:
4. Reaction of formation of amides.
Under the action of ammonia, esters are converted into amides of acids and alcohols:
The mechanism of esterification reaction.Consider as an example, the production of ethyl benzoic acid ester:
Catalytic actionsulfuric acid is that it activates the carboxylic acid molecule. Benzoic acid is protonated in an oxygen atom of the carbonyl group (an oxygen atom has a watered pair of electrons, at the expense of which the proton is joined). Protonation leads to the conversion of a partial positive charge on the carbon atom of the carboxyl group in full, to an increase in its electricity. Resonant structures (in square brackets) show the delocalization of a positive charge in the resulting cation. The alcohol molecule due to its watered pair of electrons is attached to the activated acid molecule. The proton from the alcohol residue moves to the hydroxyl group, which is converted to the "well-leaving" group H 2 O. After that, the water molecule is cleaved with simultaneous proton emissions (refund of the catalyst).
Esterification– reversible process.Direct reaction - the formation of ester, inverse - its acidic hydrolysis. In order to move the equilibrium to the right, it is necessary to remove water from the reaction mixture.
Fats and oils
Among the esters of esters, natural esters are occupied by natural esters - fats and oils, which are formed by trihatic alcohol glycerin and higher fatty acids with unbranched carbon chains containing an even number of carbon atoms. Fats are part of plant and animal organisms and play an important biological role. They serve as one of the sources of the energy of living organisms, which is distinguished by oxidation of fats. General formula of fats:
where R ", R", R "" "- hydrocarbon radicals.
Fats are "simple" and "mixed". The composition of simple fat includes the remains of the same acids (i.e. r "\u003d r" "\u003d R" "), in the composition of mixed - different.
The following fatty acids are most common in fats:
Alkanovaacid
Oil Acid CH 3 - (CH 2) 2 -Con
Kapronic acid CH 3 - (CH 2) 4 -Son
Capric acid CH 3 - (CH 2) 6 -Con
Capric acid CH 3 - (CH 2) 8 -Con
Laurinic acid CH 3 - (CH 2) 10 -Con
Miristinic acid CH 3 - (CH 2) 12 -Son
Palmitic acid CH 3 - (CH 2) 14 -Con
Stearinic acid CH 3 - (CH 2) 16 -
Arahinic acid CH 3 - (CH 2) 18 -Con
Alkenacid
Oleic acid
Alkadienicacid
Linoleic acid
Alcatrixacid
Linolenic acid
Natural fats are a mixture of simple and mixed esters.
By aggregate state at room temperature, fats are divided into liquid and solid. The aggregate state of fats is determined by the nature of fatty acids. Solidfats are usually formed by extreme acids, liquidfats (they are often called oils) - unsaturated. The melting point of fat is higher than the most of the content of limit acids. It also depends on the length of the hydrocarbon chain of fatty acid; The melting point grows with an increase in the length of the hydrocarbon radical.
The composition of animal fats is predominantly saturated acids, in the composition of vegetable - unsaturated. Therefore, animal fats, as a rule, solids, and vegetable - most often liquid (vegetable oils).
Fats are soluble in non-polar organic solvents (hydrocarbons, their halogen derivatives, diethyl ether) and insoluble in water.
1. Hydrolysis,or washer washedit occurs under the action of water (reversible) or alkalis (irreversible):
At alkaline hydrolysis, the salts of higher fatty acids are formed, called soaps.
2. Hydrogenation of fatscall the process of the addition of hydrogen to residues of non-precious acids that are part of the fats. At the same time, the remains of unsaturated acids are transferred to the remnants of limit acids, and the fats of the liquid turn into solid:
3. Liquid fats (oils containing oleic, linoles and linolenic acid), interacting with air oxygen, are able to form solid films - "Stitched polymers."Such oils are called "drying". They serve as the basis for natural oil and paints.
4. With long-term storage under the action of moisture, oxygen, air, light and heat fats acquire an unpleasant smell and taste. This process is called "Droke".Unpleasant odors and taste are due to the appearance of their conversion products in fats: free fatty acids, hydroxyc acid, aldehydes and ketones.
Fat plays an important role in human and animal life. They are one of the main sources of energy for living organisms.
Fats are widely used in the food, cosmetic and pharmaceutical industry.
Chapter 31. Carbohydrates (sugar)
Carbohydrates are natural organic compounds having a general formula with M (H 2 O) N ( t, P\u003e3). Carbohydrates are divided into three large groups: monosaccharides, oligosaccharides and polysaccharides.
Monosaccharides are called so carbohydrates that cannot be hydrolyzed with the formation of simpler carbohydrates.
Oligosaccharides are products of condensation of a small number of monosaccharides, such as sucrose - from 12 H 22 o 11. Polysaccharides (starch, cellulose) are formed by a large number of monosaccharide molecules.
Monosaccharides
Nomenclature and isomeria
The simplest monosaccharide is glycerin aldehyde, from 3 H 6 o 3:
The remaining monosaccharides according to the number of carbon atoms are divided into tetrors (C 4 H 8 O 4), pentoses (C 5 H 10 O 5) and hexoses (from 6 H 12 ° C 6). The most important hexoses are glucose and fructose. All monosaccharides are bifunctional compounds, which include unbranched carbon skeleton, several hydroxyl groups and one carbonyl group. Monosaccharides with aldehyde group called aldozami and with a ketogroup - ketosis . Below are the structural formulas of the most important monosaccharides:
All these substances contain three or four asymmetric carbon atoms, so they exhibit optical activity and can exist in the form of optical isomers. The sign in brackets in the name of the carbohydrate denotes the direction of rotation of the plane of the polarization of light: (-) indicates the left rotation, (+) - the right rotation. The letter D before the rotation sign means that in all these substances, an asymmetric carbon atom, most remote from the carbonyl group, has the same configuration (i.e., the direction of bonds with substituents), which is the glycerin aldehyde, the structure of which is presented above. Carbohydrates with the opposite configuration refer to L-row:
Note that the carbohydrates of D- and L-rows are mirror reflections of each other. Most natural carbohydrates belong to D-row.
It has been established that in the crystalline state of monosaccharides exist solely in cyclic forms. For example, glucose in solid form is usually in α-pyranous form. When dissolved in water α-glucopyranosis, slowly turns into other tautomeric forms up to the establishment of equilibrium. This is a kind of collar tautomeric system.
Isomers are compounds having an identical chemical composition, but the various structure of molecules. Isomerization of fats and oils can occur in several directions:
Isomerius in triglnseride. This type of isomerism is the regrouping of fatty acids in the glycerol molecule. Such rearrangement usually occurs when transesterification, but may also occur during thermal effects. Changing the position of fatty acid in triglenteride can affect the form of crystals, the characteristics of melting and the metabolism of lipids in the body.
Isomeria position. Unsaturated fatty acids can isomerize-Xia in acidic or alkaline environments, as well as when exposed to high temperatures by migrating double bonds from the positions 9 and 12 to other, for example, positions 9 and 10, 10 and 12 or 8 and 10. Nutritional value when moving Double Communication Pa A new position is lost, fatty acids cease to be Essenti-Al.
Spatial isomerism, double bond can have two configurations: cis- or transform. In natural fats and oils, cis-nonzomers of fatty acids are usually contained, which are most chemically active and require a relatively small amount of energy to transition to trans-isomers. Trans-isomers are characterized by a more dense packaging of molecules, allowing them to behave like saturated fatty acids with a high melting point. From the point of view of the ygien nutrition, the fatty acid trans-isomers are considered as an analogues of saturated fatty acids, both types of compounds may cause increasing LNP cholesterol in the circulatory system. 7 Engineal acids are formed at very high temperatures, mainly in hydrogenation, and to a lesser extent - during deodorization. The content / LRIANS-isomers H hydrogenated soybean and rapeseed oils can reach 55%, the isomers are predominantly trans-elaidin (C ,.,) with acid, since almost all linolenic (C1V.3) and Lino-left (C, X 2) acids Hydrogenizes to fatty acids C) to |. Isomerism caused by thermal impact, especially affecting Linolen
18 "h) acid and to a lesser extent on the fatty acid CLG 2 depends on the tempraratura and the duration of exposure. In order for the formation of the TRPS of the isomers to not exceed 1%, the deodorization temperature should not be 240 ° C, the processing duration is 1 hour, higher Temperatures can\u003e apply with less long exposure.
Conjugated Linoleic Fatty Acids - CLA). CLA is the natural isomer of linoleic acid (with | I 2), in which two double bonds are conjugate and are located in carbon atoms 9 and 11 or yu and 12, with a possible combination of cis and trans isomers. CI.A is usually producer. The anaerobic bacteria of the scar of cattle for biological hydrogenation. Modern international medical studies have shown that CLA may have properties that have favorably affecting human health, for example, antitormogenic1 and anti-studiogenic2.
