Certification work chemistry of the process of destructive hydrogenation. Classification and nomenclature of organic substances (trivial and international) Aromatic hydrocarbons oxygen-containing nitrogen-containing

Teacher:

Educational institution: professional lyceum of the metro of St. Petersburg

Academic discipline: chemistry

Subject: "Oxygen-containing and nitrogen-containing organic compounds»

The target audience: Course 1

Lesson type: generalization of the material, 1 acad. hour.

Lesson Objectives:

Knowledge: know the formulas and properties of oxygen-containing and nitrogen-containing organic matter

Understanding: understand the dependence of the properties of substances on the structure of the molecule, on the functional group

Application: use information about the properties of substances to draw up equations of chemical reactions.

Analysis: analyze the mutual influence of groups of atoms in the molecules of organic substances.

Synthesis: summarize information about the properties of organic substances in the form of a chain of transformations

Grade: conduct a self-assessment on the proposed headings.

Equipment: interactive board, multimedia presentation.

Lesson plan:

1. Org. moment

2. Repetition of previously learned.

3. Performances of students.

4. Self-determination of students by levels of self-esteem.

5. Independent work students.

6. Summing up by criteria - oriented system.

7. Homework.

During the classes

1. Organizing time.

Building a group, a report by the head of the group on the number of students present.

2. Repetition of previously learned

Information about functional groups, classes of oxygen-containing and nitrogen-containing substances, about the simplest representatives of these classes using an interactive whiteboard and multimedia presentation.

What group of atoms is necessarily present in the molecules of substances this class, determines the chemical function of a substance, i.e., its chemical properties?

Answer: functional group of atoms

Give the name of the functional group - OH

Answer: hydroxyl group of atoms.

What class of substances determines the hydroxyl group of atoms?

Answer: Alcohols, if group 1 is OH, monohydric alcohols, if more than one group is OH, polyhydric alcohols.

Give the name of the functional group - SLEEP. What class of substances does it define?

Answer: aldehyde group, defines the class of aldehydes.

Give the name of the functions to the group - SLEEP. What class does it define?

Answer: carboxyl group, defines the class of carboxylic acids.

Give the function name to the group - NH2. What class does it define?

Answer: The amino group defines the class of amines or the class of amino acids.

We listen to students' messages with a presentation multimedia presentations about the simplest representatives of various classes of oxygen-containing and nitrogen-containing substances.

3. Performances of students.

Message 1.

Ethanol C2H5OH, monohydric alcohol class, functional group - hydroxyl group of atoms - OH. Qualitative reaction - interaction with copper oxide (II) with the formation of aldehyde. Chemical properties(select 2 reactions) - combustion and interaction with metals (Na).

Message 2.

Propantriol (glycerol) C3H7 (OH) 3. Class - polyhydric alcohols, functional groups - several hydroxyl groups - OH. Qualitative reaction - interaction with copper (II) hydroxide. Chemical properties - interaction with sodium and with hydrogen halides.

Lab Experience:

Pour about 1 ml of copper (II) sumorate solution into a test tube and add a little sodium hydroxide solution until a blue precipitate of copper (II) hydroxide forms. To the resulting precipitate, add dropwise a solution of glycerin. Shake the mixture. We note the transformation of the blue precipitate into a blue solution.

(glycerol + Cu(OH)2 ----- blue solution)

Message 3.

Phenol C6H5OH is the simplest member of the phenol class.

The functional group is the hydroxyl group –OH. A qualitative reaction is the formation of a violet solution when interacting with iron (III) chloride or the formation of a white precipitate when interacting with bromine. Chemical properties: phenol is a weak acid, interacts with metals (Na) with alkalis (NaOH) and with bromine.

Message 4.

Ethanol or acetaldehyde CH3-COH Functional group - COH aldehyde group. Class - aldehydes. The qualitative reaction is the “silver mirror” reaction. Chemical properties: reduction reaction and oxidation reaction.

Laboratory experiment: demonstration experiment.

In a test tube containing 1 ml of aldehyde (aqueous solution), add a few drops of an ammonia solution of silver oxide. We heat the test tube. We observe the release of silver on the walls of the test tube, the glass surface becomes a mirror.

Message 5.

Ethanoic acid CH3-COOH (acetic acid). Class - carboxylic acids. The functional group is COOH carboxyl group. Qualitative reaction - the litmus indicator turns red.

Chemical properties: as any acid interacts with metals (Na), basic oxides (Na2O), alkalis (NaOH).

Lab Experience:

Pour a little acetic acid into a dry, clean test tube with a universal indicator. The indicator turns red.

Message 6.

Glucose C6H12O6. Class - carbohydrates. Functional groups: 5-OH and 1-COH, i.e. aldehyde alcohol. Qualitative reactions: interaction with copper hydroxide to form a blue solution. The reaction of the "silver mirror" with the release of silver on the walls of the test tube. Chemical properties: reduction to hexahydric alcohol, oxidation to gluconic acid, fermentation reaction.

Message 7.

Aniline C6H5-NH2.

Functional group - NH2 amino group. Class - amines. Qualitative reaction: interaction with bromine water with the formation of a white precipitate. Chemical properties: interaction with hydrochloric acid and with bromine.

Message 8.

Aminoethanoic acid NH2-CH2-COOH or aminoacetic acid.

Class - amino acids. Functional groups: - NH2 amino group and –COOH carboxyl group. Chemical properties: AK - amphoteric compounds; - NH2 provides basic properties, - COOH – acid properties. Therefore, amino acids are able to combine with each other, forming protein molecules, and protein is the basis of life on our planet.

4. Self-determination of students by levels of self-esteem.

Interactive board: students get acquainted with the development self-assessment map in the lesson and mark their level.

1. I can determine the functional group and the simplest representative of the class of organic substances with the help of a teacher and a summary (6-7 points).

2. I can determine the functional group, the simplest representative of the class of organic substances without the help of a teacher and without the help of a summary (8-10 points).

3. I can determine the qualitative reaction and chemical properties of a substance with the help of a teacher and notes (11-14 points).

4. I can determine the qualitative reaction and chemical properties of a substance without the help of a teacher and without a summary (15-18 points).

Class	Functional groups	The simplest representative	Qualitative reactions	Chemical properties
monatomic alcohols
Polyhydric alcohols
Phenols
Aldehydes
carboxylic acids
Carbohydrates
Amines
Amino acids

Students are introduced to a criteria-based assessment system.

Criteria:

18 - 15 points - "excellent"

points - "good"

10 - 6 points - "satisfactory"

5 or less - "unsatisfactory"

5. Independent work of students.

6. Summing up the results on a criteria-oriented system (announcement of the number of points to students).

7. Homework: filling in the table.

Test on the topic: "Oxygen-containing and nitrogen-containing organic substances" (Grade 10)

Dear students, this Verification work is the result of the study of the topic " Oxygen-containing and nitrogen-containing organic substances"and affects the setting of the mark for the trimester. You have 40 minutes to complete it. When performing, it is forbidden to use the textbook, reference materials and Intrnet.

I wish you success!

1. The hydrogen atom in the molecule has the highest activity

2. Interact with each other

3. Do not interact between themselves

4. Acetic acid can react with either of the two substances

5. Are they true the following judgments about the properties of acetic acid?

1. Acetic acid does not react with sodium carbonate.

2. Acetic acid solution conducts electricity.

6. Dehydration reaction is possible for

7. Sodium hydroxide will react with

9. The product of propanol oxidation cannot be

10. When 57.5 g of ethanol was heated with concentrated sulfuric acid, two organic compounds A and B were formed. Substance A is a gas that can discolor 100 g of a 40% solution of bromine in carbon tetrachloride. Substance B is a low-boiling liquid. Determine the resulting compounds A and B, also calculate the volume of A (at N.O.) and the mass of B, assuming that ethanol has reacted completely.

	Verified content	Tested Skills
	Properties of substances
	Phenol Properties	Ability to select one answer from four options
	Properties of alcohols	Ability to select one answer from four options
	Properties of organic acid	Ability to select one answer from four options
	Properties of organic acid	Ability to select one answer from four options
	Dehydration reactions of organic substances
	Properties of organic acids and phenol	Ability to make multiple choices
	Carrying out a chain of reactions	Ability to make multiple choices
	Properties of alcohols	Ability to make multiple choices
	Properties of alcohols	Ability to write and solve problems

Keys to the test

10. 5.6 L ethene and 37 g diethyl ether

One of the most common chemical elements included in the vast majority chemical substances is oxygen. Oxides, acids, bases, alcohols, phenols and other oxygen-containing compounds are studied in the course of inorganic and organic chemistry. In our article, we will study the properties, as well as give examples of their application in industry, agriculture and medicine.

oxides

The simplest in structure are binary compounds of metals and non-metals with oxygen. The classification of oxides includes the following groups: acidic, basic, amphoteric and indifferent. The main criterion for the division of all these substances is which element combines with oxygen. If it is metal, then they are basic. For example: CuO, MgO, Na 2 O - oxides of copper, magnesium, sodium. Their main chemical property is the reaction with acids. So, copper oxide reacts with hydrochloric acid:

CuO + 2HCl -> CuCl2 + H2O + 63.3 kJ.

The presence of atoms of non-metallic elements in the molecules of binary compounds indicates that they belong to acidic hydrogen H 2 O, carbon dioxide CO 2 , phosphorus pentoxide P 2 O 5 . The ability of such substances to react with alkalis is their main chemical characterization.

As a result of the reaction, species can be formed: acidic or medium. This will depend on how many moles of alkali react:

CO2 + KOH => KHCO3;
CO2+ 2KOH => K2CO3 + H2O.

Another group of oxygen-containing compounds, which include such chemical elements as zinc or aluminum, is referred to as amphoteric oxides. In their properties, there is a tendency to chemical interaction with both acids and alkalis. Interaction products acid oxides with water are acids. For example, in the reaction of sulfuric anhydride and water, acids are formed - this is one of the most important classes of oxygen-containing compounds.

Acids and their properties

Compounds consisting of hydrogen atoms associated with complex ions of acidic residues are acids. Conventionally, they can be divided into inorganic, for example, carbonic acid, sulfate, nitrate, and organic compounds. The latter include acetic acid, formic, oleic acids. Both groups of substances have similar properties. So, they enter into a neutralization reaction with bases, react with salts and basic oxides. Almost all oxygen-containing acids in aqueous solutions dissociate into ions, being conductors of the second kind. It is possible to determine the acidic nature of their environment, due to the excessive presence of hydrogen ions, using indicators. For example, purple litmus turns red when added to an acid solution. A typical representative of organic compounds is acetic acid containing a carboxyl group. It includes a hydrogen atom, which causes acid acids. It is a colorless liquid with a specific pungent odor, crystallizing at temperatures below 17 ° C. CH 3 COOH, like other oxygen-containing acids, is perfectly soluble in water in any proportion. Its 3 - 5% solution is known in everyday life under the name of vinegar, which is used in cooking as a seasoning. The substance has also found its application in the production of acetate silk, dyes, plastics and some medicines.

Organic compounds containing oxygen

In chemistry, one can distinguish a large group of substances containing, in addition to carbon and hydrogen, also oxygen particles. These are carboxylic acids, esters, aldehydes, alcohols and phenols. All their chemical properties are determined by the presence in the molecules of special complexes - functional groups. For example, alcohol containing only limit bonds between atoms - ROH, where R is a hydrocarbon radical. These compounds are usually considered as derivatives of alkanes, in which one hydrogen atom is replaced by a hydroxo group.

Physical and chemical properties of alcohols

State of aggregation alcohols are liquids or solid compounds. There are no gaseous substances among alcohols, which can be explained by the formation of associates - groups consisting of several molecules connected by weak hydrogen bonds. This fact also determines the good solubility of lower alcohols in water. However, in aqueous solutions, oxygen-containing organic substances - alcohols, do not dissociate into ions, do not change the color of indicators, that is, they have a neutral reaction. The hydrogen atom of the functional group is weakly bonded to other species, so in chemical interactions capable of leaving the molecule. At the same place of free valency, it is replaced by other atoms, for example, in reactions with active metals or with alkalis - by metal atoms. In the presence of catalysts such as platinum mesh or copper, alcohols are oxidized by vigorous oxidizing agents, potassium bichromate or potassium permanganate, to aldehydes.

esterification reaction

One of the most important chemical properties of oxygen-containing organic substances: alcohols and acids is a reaction leading to the production of esters. It is of great practical importance and is used in industry for the extraction of esters used as solvents in the food industry (in the form of fruit essences). In medicine, some of the esters are used as antispasmodics, for example, ethyl nitrite dilates peripheral blood vessels, and isoamyl nitrite is a protector of coronary artery spasms. The esterification reaction equation has the following form:

CH3COOH+C2H5OH<--(H2SO4)-->CH3COOC2H5+H2O

In it, CH 3 COOH is acetic acid, and C 2 H 5 OH is chemical formula alcohol ethanol.

Aldehydes

If a compound contains the -COH functional group, then it is classified as an aldehyde. They are presented as products of further oxidation of alcohols, for example, with oxidizing agents such as copper oxide.

The presence of a carbonyl complex in the molecules of formic or acetaldehyde determines their ability to polymerize and attach atoms of other chemical elements. Qualitative reactions, with which you can prove the presence of a carbonyl group and the belonging of a substance to aldehydes, are the reaction of the silver mirror and the interaction with copper hydroxide when heated:

Acetaldehyde, used in industry for the production of acetic acid, has received the greatest use - a lot of tonnage product organic synthesis.

Properties of oxygen-containing organic compounds - carboxylic acids

The presence of a carboxyl group - one or more - is a hallmark of carboxylic acids. Due to the structure of the functional group, dimers can form in acid solutions. They are linked together by hydrogen bonds. The compounds dissociate into hydrogen cations and acid residue anions and are weak electrolytes. An exception is the first representative of a number of limiting monobasic acids - formic, or methane, which is a conductor of the second kind of medium strength. Presence in molecules of only simple sigma bonds speaks of limiting, but if substances have double pi bonds in their composition, these are unsaturated substances. The first group includes such acids as methane, acetic, butyric. The second is represented by compounds that are part of liquid fats - oils, for example, oleic acid. The chemical properties of oxygen-containing compounds: organic and inorganic acids are largely similar. So, they can interact with active metals, their oxides, with alkalis, and also with alcohols. For example, acetic acid reacts with sodium, oxide, and to form a salt - sodium acetate:

NaOH + CH3COOH→NaCH3COO + H2O

A special place is occupied by compounds of higher carboxylic oxygen-containing acids: stearic and palmitic, with a trihydric saturated alcohol - glycerin. They belong to esters and are called fats. The same acids are part of the sodium and potassium salts as an acid residue, forming soaps.

Important organic compounds that are widely distributed in wildlife and play a leading role as the most energy-intensive substance are fats. They are not an individual compound, but a mixture of heterogeneous glycerides. These are compounds of the limit polyhydric alcohol- glycerin, which, like methanol and phenol, contains hydroxyl functional groups. Fats can be subjected to hydrolysis - heating with water in the presence of catalysts: alkalis, acids, oxides of zinc, magnesium. The products of the reaction will be glycerol and various carboxylic acids, further used for the production of soap. In order not to use expensive natural essential carboxylic acids in this process, they are obtained by oxidizing paraffin.

Phenols

Finishing to consider the classes of oxygen-containing compounds, let us dwell on phenols. They are represented by a phenyl radical -C 6 H 5 connected to one or more functional hydroxyl groups. The simplest representative of this class is carbolic acid, or phenol. As a very weak acid, it can interact with alkalis and active metals - sodium, potassium. A substance with pronounced bactericidal properties - phenol is used in medicine, as well as in the production of dyes and phenol-formaldehyde resins.

In our article, we studied the main classes of oxygen-containing compounds, and also considered their chemical properties.

Heteroorganic compounds (sulphur-, oxygen- and nitrogen-containing) of various structure and molecular weight are present in various proportions in distillate and residual oil fractions. It is especially difficult to study the nature and composition of high-molecular heteroorganic compounds, the main part of which are tar-asphalten substances. Due to lone pairs of electrons, sulfur, oxygen, and nitrogen heteroatoms are able to act as a coordinating center in the formation of associates in oil systems.

Sulfur compounds belong to the most representative group of heteroatomic components of gas condensate and oil systems. The total sulfur content in oil and gas systems varies widely: from hundredths of a percent to 6-8% (wt.) and more. A high content of total sulfur is characteristic of gas condensates from the Astrakhan, Karachaganak (0.9%) and other fields. The content of sulfur-containing compounds in some oils reaches 40% (wt.) and above, in some cases, the oil consists almost entirely of them. Unlike other heteroatoms, which are predominantly concentrated in CAB, a significant proportion of sulfur is contained in distillate fractions. As a rule, the sulfur content in straight-run fractions increases as their boiling point and total sulfur content of the original oil increase.

Minor amounts of inorganic sulfur-containing compounds (elemental sulfur and hydrogen sulfide) are present in oil and gas systems, they can also be formed as secondary decomposition products of other sulfur-containing compounds at high temperatures in the processes of distillation, destructive processing. Among the sulfur-containing compounds found in oil, the following have been identified (according to the Institute of Petroleum Chemistry, TF SB RAS).

1. Aliphatic, alicyclic and aromatic thiols (mercaptans) R-SH:

C 6 H 5 C n H 2 n +1 SH C n H 2 n +1 C 6 H 5 SH C 10 H 7 SH

arenoalkanothiols thionaphthols

2. Thioethers (sulfides) of the following main types:

R-S-R" C 6 H 5 -S-C 6 H 5

thiaalkanes, thiaalkenes, thiaalkyne diarylsulfides

thiacycloalkanes alkylarylsulfides arylthiaalkanes

(R, R" - saturated and unsaturated aliphatic hydrocarbon substituents).

3. Dialkyd disulfides R-S-S-R", where R, R" are alkyl, cycloalkyl or aryl substituents.

4. Thiophenes and their derivatives, the most important of which are the following arenothiophenes:

alkylbenzothiophenes alkylbenzothiophenes alkyldibenzothiophenes

The distribution of various groups of sulfur-containing compounds in oils and in oil fractions is subject to the following regularities.

Thiols are contained in almost all crude oils, usually in small concentrations and make up 2-10% (wt.) Of the total content of sulfur-containing compounds. In gas condensates, there are mainly aliphatic mercaptans C 1 -C z. Some oils and gas condensates and their fractions are natural concentrates of mercaptans, examples of which are gasoline fractions of the super-giant Caspian field; fraction 40-200°C of gas condensate of the Orenburg field, containing 1.24% (wt.) of total sulfur, including 0.97% mercaptan; light kerosene fraction 120-280°C of oil from the Tengiz field, containing 45-70% mercaptan sulfur of the total content of sulfur-containing compounds. At the same time, the reserves of natural thiols in the hydrocarbon raw materials of the Caspian region correspond to the level of their global synthetic production. Natural thiols are promising raw materials for the synthesis of pesticides (based on symmetrical triazines) and odorization of liquefied gases. Russia's prospective demand for thiols for odorization is currently 6,000 tons/year.

Thioethers account for up to 27% of the total sulfur-containing compounds in crude oils and up to 50% in medium fractions; in heavy vacuum gas oils, the content of sulfides is lower. Methods for separating petroleum sulfides are based on their ability to form complex compounds of the donor-acceptor type by transferring a lone pair of electrons from a sulfur atom to a free acceptor orbital. Metal halides, haloalkyls, and halogens can act as electron acceptors. Complexation reactions with petroleum sulfides, unfortunately, are not selective; other heteroatomic components of oil can also take part in the formation of complexes.

Dialkyl disulfides are not found in crude oils, they are usually formed during the oxidation of mercaptans under mild conditions and therefore are present in gasolines (up to 15%). The main share of sulfur-containing compounds in oils falls on the so-called "residual" sulfur, which is not determined by standard methods. Thiophenes and their derivatives predominate in its composition, therefore, earlier, "residual" sulfur was called "thiophene", however, using negative ion mass spectrometry, previously undetectable sulfoxides, sulfones, and disulfane were found in it. In gasoline fractions, the content of thiophene derivatives is low; in medium and especially high-boiling fractions, it reaches 50-80% of the total sulfur-containing compounds. The relative content of thiophene derivatives, as a rule, coincides with the degree of aromaticity of the oil system. Difficulties arising in the isolation of sulfur-containing compounds (especially from high-boiling fractions) are caused by the closeness of the chemical properties of arenes and thiophenes. The similarity of their chemical behavior is due to the aromaticity of thiophenes, which arises as a result of the incorporation of a sulfur heteroatom into the π-electron system up to an aromatic sextet. The consequence of this is an increased tendency of petroleum thiophenes to intense intermolecular interactions.

Oxygen compounds contained in oil systems from 0.1-1.0 to 3.6% (wt.). With an increase in the boiling point of distillate fractions, their content increases, and the main part of oxygen is concentrated in tar-asphalten substances. The composition of oils and distillates contains up to 20% or more oxygen-containing compounds.

Among them, substances of an acidic and neutral nature are traditionally distinguished. The acid components include carboxylic acids and phenols. Neutral oxygen-containing compounds are represented by ketones, anhydrides and acid amides, esters, furan derivatives, alcohols and lactones.

The presence of acids in oils was discovered a very long time ago due to the high chemical activity compared to hydrocarbons. The history of their discovery in oil is as follows. Upon receipt of kerosene High Quality for lighting purposes, it was treated with alkali (acid-base cleaning) and the formation of substances with a high emulsifying ability was observed. Subsequently, it turned out that the emulsifiers are sodium salts of acids contained in distillate fractions. Extraction with aqueous and alcoholic solutions of alkalis is still a classic method for extracting acidic components from oils. Currently, methods for isolating acids and phenols are also based on the interaction of their functional groups (carboxylic and hydroxyl) with any reagent.

Carboxylic acids are the most studied class of oxygen-containing oil compounds. The content of petroleum acids by fractions varies according to an extreme dependence, the maximum of which, as a rule, falls on light and medium oil fractions. Various types of petroleum acids have been identified by chromato-mass spectrometry. Most of them are monobasic (RCOOH), where almost any fragment of hydrocarbon and heteroorganic compounds of oil can be used as R. It has long been noted that the group compositions of acids and oils correspond to each other: aliphatic acids predominate in methane oils, naphthenic and naphthenoaromatic acids predominate in naphthenic oils. Aliphatic acids from C 1 to C 25 with a linear structure and some with a branched structure have been found. At the same time, the ratio of n-alkanoic and branched acids in petroleum acids coincides with the ratio of the corresponding hydrocarbons in oils.

Aliphatic acids are represented primarily by n-alkanoic acids. Of the branched acids, those containing a methyl substituent in the main chain are more common. All the lower isomers of this type are found in oils, down to C 7 . Another important group of aliphatic acids is isoprenoid acids, among which prestanic (C 19) and phytanic (C 20) acids dominate.

Alicyclic (naphthenic) acids of oil are monocyclocarboxylic acids - derivatives of cyclopentane and cyclohexane; polycyclic can contain up to 5 rings (data for California oil). The COOH groups in the molecules of monocyclic acids are directly connected to the cycle or are located at the end of aliphatic substituents. There can be up to three (most often methyl) substituents in the cycle, the most common positions of which are 1, 2; thirteen; 1, 2, 4; 1, 1, 3 and 1, 1, 2, 3.

Molecules of tri-, tetra- and pentacyclic acids isolated from oils are built mainly from condensed cyclohexane rings.

The presence of hexacyclic naphthenic acids with cyclohexane rings in oils has been established. Aromatic acids in oils are represented by benzoic acid and its derivatives. Many homologous series of polycyclic naphthenoaromatic acids were also found in oils, and monoaromatic steroid acids were identified in Samotlor oil.

From oxygen-containing compounds, petroleum acids are characterized by the highest surface activity. It has been established that the surface activity of both low-resin and high-resin oils decreases significantly after the removal of acidic components (acids and phenols) from them. Strong acids take part in the formation of associates of oils, which is shown in the study of their rheological properties.

Phenols have been studied much worse than acids. Their content in oils from West Siberian fields ranges from 40 to 900 mg/l. In West Siberian oils, the concentrations of phenols increase in the order C 6<С 7 << С 8 <С 9 . В нефтях обнаружены фенол, все крезолы, ксиленолы и отдельные изомеры С 9 . Установлено, что соотношение между фенолами и алкилфенолами колеблется в пределах от 1: (0,3-0,4) до 1: (350-560) и зависит от глубины залегания и возраста нефти. В некоторых нефтях идентифицирован β-нафтол. Высказано предположение о наличии соединений типа о-фенилфенолов, находящихся в нефтях в связанном состоянии из-за склонности к образованию внутримолекулярных водородных связей. При исследовании антиокислительной способности компонентов гетероор-ганических соединений нефти установлено, что концентраты фенольных соединений являются наиболее активными природными ингибиторами.

All the simplest alkyl ketones C3-C6, acetophenone and its naphtheno- and areno-derivatives, fluorenone and its closest homologs were found in neutral oxygen-containing compounds of Californian oils. The yield of ketone concentrate from Samotlor oil, consisting mainly of dialkyl ketones, is 0.36%, while the degree of extraction of ketones is only 20%, which indicates the presence of ketones of large molecular weights that cannot be recovered by this method. In the study of ketones in the oils of Western Siberia, it was found that they contain C 19 -C3 2 ketones, and aliphatic ketones predominate in methane oils, and cyclane and aromatic substituents predominate in naphthenic oils.

It can be assumed that oils contain alcohols in the free state; in the bound state, they are part of esters. Of the heteroorganic compounds of oil, the propensity of oxygen-containing compounds to intense intermolecular interactions has been most studied.

The study of nitrogen-containing compounds is possible in two ways - directly in crude oil and after their isolation and separation. The first way makes it possible to study nitrogen-containing compounds in a state close to natural, however, the occurrence of noticeable errors due to the low concentration of these compounds is not ruled out. The second way allows such errors to be reduced, but in the process of chemical action on oil during separation and isolation, a change in their structure is possible. It has been established that nitrogen-containing compounds in oil are represented mainly by cyclic compounds. Aliphatic nitrogen-containing compounds are found only in products of destructive oil refining, in which they are formed as a result of the destruction of nitrogenous heterocycles.

All nitrogen-containing oil compounds are, as a rule, functional derivatives of arenes, and therefore have a molecular weight distribution similar to them. However, unlike arenes, nitrogen-containing compounds are concentrated in high-boiling oil fractions and are a component of CAB. Up to 95% of the nitrogen atoms present in oil are concentrated in resins and asphaltenes. It has been suggested that during the isolation of resins and asphaltenes, even relatively low molecular weight nitrogen-containing compounds are co-precipitated with them in the form of donor-acceptor complexes.

In accordance with the generally accepted classification according to the acid-base characteristic nitrogen-containing compounds are dividedinto nitrogenous bases and neutral compounds.

Nitrogen-containing bases are, apparently, the only carriers of the main properties among the components of oil systems. The proportion of nitrogen-containing bases in oil titrated with perchloric acid in an acetic acid medium ranges from 10 to 50%. Currently, more than 100 alkyl- and areno-condensed analogues of pyridine, quinoline, and other bases have been identified in oils and oil products.

Strongly basic nitrogen-containing compounds are represented by pyridines and their derivatives:

Weakly basic nitrogen-containing compounds include anilines, amides, imides and N-cycloalkyl derivatives having alkyl, cycloalkyl and phenyl groups as a substituent in the pyrrole ring:

In the composition of crude oils and straight-run distillates, pyridine derivatives are most often found. With an increase in the boiling point of fractions, the content of nitrogen-containing compounds usually increases, while their structure changes: if pyridines predominate in light and medium fractions, then their polyaromatic derivatives predominate in heavier fractions, and anilines are present to a greater extent in the products of thermal processing at elevated temperatures. Nitrogenous bases predominate in light fractions, and neutral nitrogen-containing compounds, as a rule, dominate in heavy fractions.

Neutral nitrogen-containing compounds that do not contain other heteroatoms in their molecules, except for the nitrogen atom, and isolated from oil, include indoles, carbazoles and their naphthenic and sulfur-containing derivatives:

When isolated, neutral nitrogen-containing compounds form associates with oxygen-containing compounds and are extracted along with nitrogen-containing bases.

Along with the named monofunctional compounds, the following nitrogen-containing compounds have been identified in oils:

1. Polyaromatic with two nitrogen atoms in the molecule:

2. Compounds with two heteroatoms (nitrogen and sulfur) in one cycle - thiazoles and benzthiazoles and their alkyl and naphthenic homologues:

3. Compounds with two nitrogen and sulfur heteroatoms in different cycles: thiophene-containing alkyl-, cycloalkylindoles and carbazoles.

4. Compounds with a carbonyl group in a nitrogen-containing heterocycle, such as piperidones and quinolones:

5. Porphyrins. The structure of porphyrins, which are complex compounds with vanadyl VO, nickel, and iron, will be discussed below.

The importance of nitrogen-containing compounds of oil as natural surfactants is very high; they, along with CAB, largely determine the surface activity at liquid phase boundaries and the wetting ability of oil at rock-oil, metal-oil interfaces. Nitrogen-containing compounds and their derivatives - pyridines, hydroxypyridines, quinolines, hydroxyquinolines, imidazolines, oxazolines, etc. - are natural oil-soluble surfactants that have inhibitory properties in the corrosion of metals during the production, transportation and refining of oil. Weaker surface-active properties are characteristic of such nitrogen-containing oil compounds as homologues of pyrrole, indole, carbazole, thiazoles and amides.

Resin-asphalten substances (CAB). One of the most representative groups of heteroorganic macromolecular oil compounds are CAB. The characteristic features of CAB - significant molecular weights, the presence of various heteroelements in their composition, polarity, paramagnetism, a high tendency to MMW and association, polydispersity and the manifestation of pronounced colloidal disperse properties - contributed to the fact that the methods usually used in the analysis turned out to be unsuitable for their study. low boiling components. Given the specifics of the object under study, Sergienko S.R. more than 30 years ago, he singled out the chemistry of macromolecular oil compounds as an independent branch of petroleum chemistry and made a major contribution to its formation with his fundamental works.

Until the 1960s and 1970s, researchers determined the physicochemical characteristics of CAB (some of them are given in Table 2.4) and tried to represent the structural formula of the average molecule of asphaltenes and resins based on instrumental structural analysis data.

Similar attempts are being made at the present time. The values of the elemental composition, average molecular weights, density, solubility, etc., varying within a significant range for CAB samples of various domestic and foreign oils reflect the diversity of natural oils. Most of the heteroelements present in oil and almost all metals are concentrated in resins and asphaltenes.

Nitrogen in CAB mainly enters into heteroaromatic fragments of pyridine (basic), pyrrole (neutral), and porphyrin (metal complex) types. Sulfur is part of heterocycles (thiophene, thiacyclane, thiazole), thiol groups, and sulfide bridges that cross-link molecules. Oxygen in resins and asphaltenes is presented in the form of hydroxyl (phenolic, alcohol), carboxyl, ether (simple, complex lactone), carbonyl (ketone, quinone) groups and furan cycles. There is a certain correspondence between the molecular weight of asphaltenes and the content of heteroelements (Fig. 2.2).

Let us characterize the modern level of ideas about CAB. Yen notes the universal nature of asphaltenes as a constituent of natural carbon sources, not only caustobioliths (oils and solid fuels), but also sedimentary rocks and meteorites.

According to the classification of natural resources with a hydrocarbon base proposed by Abraham, oils include those that contain up to 35-40% (wt.) CAB, and natural asphalts and bitumens contain up to 60-75% (wt.) CAB, according to other sources - up to 42-81%. In contrast to the lighter components of oil, which were attributed to their groups by the similarity of their chemical structure, the criterion for combining compounds into a class called CAB is their proximity in solubility in a particular solvent. When oil and oil residues are exposed to large amounts of petroleum ether, low-boiling alkanes, precipitation of substances called asphaltenes, which are soluble in lower arenas, and the solvation of other components - maltenes, consisting of a hydrocarbon part and resins.

Rice. 2.2. Dependence of the molecular mass of asphaltenes (М) on the average total content of heteroelements (O+N+S) in oil from the Safagna (1), Cerro Negro (2), Boscan (4), Batiraman (5) and light Arabian oil fields ( 3)

Modern schemes for separating the heavy part of oil are based on the classical methods first proposed by Markusson. Substances insoluble in carbon disulfide and other solvents are classified as carboids. Substances that are soluble only in carbon disulfide and precipitated by carbon tetrachloride are called carbenes. Carboids and carbenes, as a rule, are found in the composition of heavy products of destructive oil refining in an amount of several percent and will be considered separately below. They are practically absent in the composition of crude oils and in the residues of primary oil refining.

The properties of isolated asphaltenes also depend on the solvent. A consequence of differences in the nature and properties of solvents is that the molecular weight of asphaltenes from Arab oils when dissolved in benzene is on average 2 times higher than in tetrahydrofuran. (Table 2. 5).

Table 2.5

Solvent Solution parameter Dielectric Dipole moment, Dpermeability permeability

Tetrahydrofuran 9.1 7.58 1,75 Benzene 9.2 2.27 0

In the process of developing ideas about the structure and nature of petroleum CABs, two main stages can be distinguished, related by the general idea of a colloidal-dispersed structure, but differing in the methodological approach to assessing the structure of a single element of a colloidal structure. At the first stage - the stage of chemical ideas about the structure of CAB molecules - a standard chemical approach was used to identify the structure of an unknown compound. After establishing the molecular weight, elemental composition and molecular formulas of resins and asphaltenes C n H 2 n - z N p S g O r . Then the z value was calculated. For resins, it was 40-50, for asphaltenes - 130-140. A typical example of the results of such studies for CAB samples of various domestic and foreign oils is presented in Table. 2.4. (see Table 1.4). As can be seen, asphaltenes differ from resins from the same source in higher carbon and metal content and lower hydrogen content, larger polyaromatic cores, shorter average length of large aliphatic substituents, and fewer acyclic fragments directly fused with aromatic nuclei.

The second stage can be characterized as the stage of development of physical ideas about the structure of asphaltenes and analysis of the reasons for the tendency of asphaltenes to associate. Indeed, the explanation of the dependence of the molecular weight on the conditions of determination (see Table 2.5), as well as its linear dependence on the size of asphaltene particles (Fig. 1.5) became possible within the framework of qualitatively new ideas about the structure of asphaltenes.

In 1961 T. Yen proposed the so-called "plate to plate" stack model of the structure of asphaltenes. The model was based not on the necessity of its compliance with the calculated structural parameters of the composition of asphaltenes, but on the fundamental possibility of a plane parallel orientation of polyaromatic fragments of different molecules. Their association as a result of intermolecular (π - π, donor-acceptor, etc.) interactions occurs with the formation of layered stacking structures (the term "stacking" is used in molecular biology to denote a stack-like arrangement of molecules one above the other).

Rice. 2.5. Correlation between the particle size of asphaltenes (D) and their molecular weight (M)

In accordance with the Yen model based on X-ray diffraction data, asphaltenes have a crystalline structure and are stacking structures with a diameter of 0.9-1.7 nm from 4-5 layers spaced 0.36 nm apart. The size of stacking structures along the normal to the plane of aromatic plates is 1.6–2.0 nm (Fig. 2.6). Rectilinear segments show flat polyaromatic fragments, and broken segments show saturated fragments of molecules. Polyaromatic fragments are represented by relatively small, most often no more than tetracyclic, nuclei. Of the aliphatic fragments, the most common are short alkyl groups C 1 -C 5, primarily methyl, but there are also linear branched alkanes containing 10 carbon atoms or more. There are also polycyclic saturated structures in CAB molecules with 1-5 condensed rings, mainly bicyclanes.

Within the framework of the Jena model, the dependence of the molecular weight of asphaltenes on the conditions of isolation and the nature of the solvent noted above can be easily explained by an association that suggests several levels of structural organization of asphaltenes: a molecularly dispersed state (I), in which asphaltenes are in the form of separate layers; colloidal state (II), which is the result of the formation of stacking structures with characteristic dimensions; a dispersed kinetically stable state (III) arising from the aggregation of stacking structures; and a dispersed kinetically unstable state (IV) accompanied by precipitation.

Rice. 2.6. Asphaltene structure model according to Jen

Models of the pack structure of the structure of asphaltenes are followed by many modern researchers. Unger F.G. expressed an original point of view on the process of occurrence and existence of CAB in oil. Oils and oil systems containing CAB, in his opinion, are thermodynamically labile paramagnetic associated solutions. The cores of associates of such solutions are formed by asphaltenes, in which stable free radicals are localized, and the solvate layers surrounding the cores consist of diamagnetic resin molecules. Some of the diamagnetic resin molecules are capable of transitioning to an excited triplet state and undergoing hemolysis. Therefore, resins are a potential source of asphaltenes, which explains L.G. the ease of converting resins to asphaltenes.

Thus, the novelty of the presented ideas is connected with the assertion of the special role of exchange interactions for explaining the nature of CAB. In contrast to the pack model, the idea of a centrally symmetric structure of the CAB particle is being developed. It was first postulated by D. Pfeiffer and R. Saal, who proposed a static model of the structure of the structural unit of asphaltenes. According to it, the core of the structural unit is formed by high molecular weight polycyclic hydrocarbons and is surrounded by components with a gradually decreasing degree of aromaticity. Neumann G. emphasized that it is energetically beneficial to turn polar groups inside the structural unit, and hydrocarbon radicals - outward, which is in agreement with the rule of polarity equalization according to Rebinder.

Porphyrins are typical examples of native petroleum complex compounds. Porphyrins with vanadium as the focal point (in the form of vanadyl) or nickel (see 11). Oil vanadylporphyrins are mainly homologues of two series: alkyl-substituted porphyrins with different total number of carbon atoms in the side substituents of the porphine ring and porphyrins with an additional cyclopentene ring. Metal porphyrin complexes are present in natural bitumen up to 1 mg/100 g, and in high-viscosity oils - up to 20 mg/100 g of oil. In the study of the nature of the distribution of metal porphyrin complexes between the constituent parts of the SDS in the work by extraction and gel chromatography, it was found that 40% of vanadylporphyrins are concentrated in dispersed particles (approximately equally in the composition of the core and solvate layer), and the rest of them and nickel porphyrins are contained in the dispersion environment.

Vanadylporphyrins in the composition of asphaltenes make a significant contribution to the surface activity of oils, while the intrinsic surface activity of asphaltenes is low. Thus, a study of oils from Bashkiria showed that the surface tension of oils at the boundary with water strongly correlates with the content of vanadylporphyrins in them, while the correlation coefficient with the content of asphaltenes in them is relatively low (Fig. 2.7).

To a lesser extent, the effect of metal porphyrins on the disperse structure of oil and the conditions for the occurrence of phase transitions in oil systems has been studied. There is evidence of their negative effect, along with other heteroatomic components, on the catalytic processes of oil refining. In addition, they should strongly influence the kinetics and mechanism of phase transitions in SSS.

Rice. 2.7. Isotherms of interfacial tension a at the boundary with water:

a - benzene solutions of asphaltenes: 1 - asphaltenes with porphyrins; 2-5 - asphaltenes as porphyrins are removed after one, five, seven, thirteen extractions, respectively; b - oil of Bashkiria

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