1. R. Oxidation.

Aldehydes are easily oxidized to carboxylic acids. Oxidizing agents can be copper(II) hydroxide, oxidesilver, air oxygen:

Aromatic aldehydes are more difficult to oxidize than aliphatic ones. Ketones, as mentioned above, are more difficult to oxidize than aldehydes. Oxidation of ketones is carried out under harsh conditions, in the presence of strong oxidizing agents. Formed as a result of a mixture of carboxylic acids. How to distinguish aldehydes from ketones? The difference in oxidation ability serves as the basis for qualitative reactions that distinguish aldehydes from ketones. Many mild oxidizing agents react readily with aldehydes but are inert towards ketones. a) Tollens' reagent (ammonia solution of silver oxide), containing complex ions +, gives a “silver mirror” reaction with aldehydes. This produces metallic silver. A silver oxide solution is prepared nepo indirectly d experience:

Tollens' reagent oxidizes aldehydes to the corresponding carboxylic acids, which form ammonium salts in the presence of ammonia. The oxidizing agent itself is reduced to metallic silver in this reaction. Due to the thin silver coating on the walls of the test tube that is formed during this reaction, the reaction of aldehydes with an ammonia solution of silver oxide is called the “silver mirror” reaction. CH3-CH=O)+2OH->CH3COONH4+2Ag+3NH3+H2O. Aldehydes also reduce freshly prepared light blue ammonia solution of copper(II) hydroxide (Fehling's reagent) to yellow copper(I) hydroxide, which decomposes when heated to release a bright red precipitate of copper(I) oxide. CH3-CH=O + 2Cu(OH)2 - CH3COOH+2CuOH+H2O 2CuOH->Cu2O+H2O

2. R. Accessions

Hydrogenation is the addition of hydrogen.

Carbonyl compounds are reduced to alcohols with hydrogen, lithium aluminum hydride, and sodium borohydride. Hydrogen is added via the C=O bond. The reaction is more difficult than the hydrogenation of alkenes: heat, high pressure and a metal catalyst (Pt, Ni) are required:

3. Interaction with water Ouch.

4. Interaction with alcohols.

When aldehydes react with alcohols, hemiacetals and acetals can be formed. Hemiacetals are compounds that contain a hydroxyl and an alkoxy group at one carbon atom. Acetals include substances whose molecules contain a carbon atom with two alkoxy substituents.

Acetals, unlike aldehydes, are more resistant to oxidation. Due to the reversibility of interaction with alcohols, they are often used in organic synthesis to “protect” the aldehyde group.

4.Addition of hydrosulfites.

Hydrosulfite NaHSO3 also adds at the C=O bond to form a crystalline derivative from which the carbonyl compound can be regenerated. Bisulfite derivatives are used for the purification of aldehydes and ketones.

As a result of the polycondensation of phenol with formaldehyde in the presence of catalysts, phenol-formaldehyde resins are formed, from which plastics - phenol plastics (bakelites) are produced. Phenolic plastics are the most important substitutes for non-ferrous and ferrous metals in many industries. They are used to make a large number of consumer products, electrical insulating materials and construction parts. A fragment of phenol-formaldehyde resin is shown below:

The starting compounds for the production of aldehydes and ketones can be hydrocarbons, halogen derivatives, alcohols and acids.

Application of carbonyl compounds

Formaldehyde is used to produce plastics, such as bakelite, leather tanning, disinfection, and seed dressing. More recently, a method for producing polyformaldehyde (-CH2-O-)n, which has high chemical and thermal stability, has been developed in our country.

This is the most valuable structural plastic, capable of replacing metals in many cases. Acetaldehyde is used to produce acetic acid and some plastics. Acetone is used as a starting material for the synthesis of many compounds (for example, methyl methacrylate, the polymerization of which produces plexiglass); it is also used as a solvent.

Question 1. Aldehydes. Their structure, properties, preparation and application.

Answer. Aldehydes are organic substances whose molecules

General formula of aldehydes ˸

Nomenclature

The name of aldehydes is derived from the historical names of carboxylic acids with the same number of carbon atoms. So, CH 3 CHO is acetaldehyde. According to systematic nomenclature, the name of aldehydes is derived from the names of hydrocarbons with the addition of the ending - al, CH 3 CHO – ethanal. The numbering of the carbon chain begins with the carbonyl group. For branched isomers, the names of the substituents are written before the name of the aldehyde, indicating the number and number of the carbon atom to which they are connected˸

CH 3 – CH (CH 3) – CH 2 – CHO.

3-methylbutanal

Isomerism

Carbon skeleton ˸

CH 3 – CH 2 – CH 2 – CHO – butanal,

CH 3 – CH(CH 3) – CHO – 2-methylpropanal.

Connection classes ˸

CH 3 – CH 2 – CHO – propanal,

CH 3 – CO – CH 3 – propanone (acetone).

Physical properties

Methanal is a gas, aldehyde from C 2 to C 13 is liquid, higher aldehydes are solids (tetradecanal or myristic aldehyde CH 3 (CH 2) 12 CHO has a melting point of 23.5). Lower aldehydes are highly soluble in water; the more carbon atoms in the molecule, the less solubility; Aldehydes do not have hydrogen bonds.

Chemical properties

1. Addition reactions ˸

a) hydrogenation ˸

CH 2 O + H 2 = CH 3 OH;

b) formation of acetals with alcohols ˸

CH 3 - CH 2 – CHO + 2C 2 H 5 OH = CH 3 – CH 2 – CH(OC 2 H 5) 2 + H 2 O.

2. Oxidation reaction˸

a) reaction of the “silver mirror” ˸

CH 3 CHO + Ag 2 O 2 Ag + CH 3 COOH;

b) interaction with copper (II) hydroxide ˸

CH 3 CHO + 2Cu(OH) 2 CH 3 COOH + Cu 2 O↓ + 2H 2 O

3. Substitution reactions˸

CH 3 CH 2 CHO + Br 2 = CH 3 – CH (Br) – CHO+ HBr

4.Polymerization˸

CH3=O (CH 2 O) 3 .

trioxymethylene

5.Polycondensation˸

n C6H5OH+ n CH2O+ n C 6 H 5 OH + …=

=[ C 6 H 4 (OH) – CH 2 – C 6 H 4 (OH)] n + n H2O

Phenol formaldehyde resin

Receipt

a) Oxidation of alkanes˸

CH 4 + O 2 CH 2 O + H 2 O.

methanal

b) Oxidation of alcohols˸

2CH 3 OH + O 2 2CH 2 O + 2H 2 O.

c) Kucherov reaction˸

C 2 H 2 + H 2 O CH 3 CHO.

d) Oxidation of alkenes˸

C 2 H 4 + [O] CH 3 CHO.

Application˸

1. Production of phenol-formaldehyde resins and plastics.

2. Production of drugs, formaldehyde (from CH 2 =O).

3. Production of dyes.

4. Production of acetic acid.

5. Disinfection and seed treatment.

Question 2. Environmental protection problem .

Answer˸ Today the largest scale is environmental pollution by chemicals.

Atmospheric protection

Sources of pollution: ferrous and non-ferrous metallurgy enterprises, thermal power plants, motor vehicles.

Industry˸ emissions of sulfur and nitrogen oxides. As a result of roasting sulfide ores of non-ferrous metals, sulfur (IV) oxide is released.

Thermal power plants emit SO 2 and SO 3, which combine with air moisture (SO 3 + H 2 O = H 2 SO 4) and fall out in the form of acid rain.

Question 1. Aldehydes. Their structure, properties, preparation and application. - concept and types. Classification and features of the category "Question 1. Aldehydes. Their structure, properties, preparation and use." 2015, 2017-2018.

Organic drugs

We study drugs divided into groups according to chemical classification. The advantage of this classification is the ability to identify and study general patterns in the development of methods for obtaining drugs that make up the group, methods of pharmaceutical analysis based on the physical and chemical properties of substances, and establishing a connection between chemical structure and pharmacological action.

All drugs are divided into inorganic and organic. Inorganic, in turn, are classified according to the position of the elements in the PS. And organic ones are divided into derivatives of the aliphatic, alicyclic, aromatic and heterocyclic series, each of which is divided into classes: hydrocarbons, halogen derivatives of hydrocarbons, alcohols, aldehydes, ketones, acids, ethers and esters, etc.

ALIPHATIC COMPOUNDS, LIKE DRUGS.

Preparations of aldehydes and their derivatives. Carbohydrates

Aldehydes

This group of compounds includes organic medicinal substances containing an aldehyde group or their functional derivatives.

General formula:

Pharmacological properties

The introduction of an aldehyde group into the structure of an organic compound gives it a narcotic and antiseptic effect. In this regard, the action of aldehydes is similar to the action of alcohols. But unlike the alcohol group, the aldehyde group increases the toxicity of the compound.

Factors influencing the structure on the pharmacological action :

elongation of the alkyl radical increases activity, but at the same time toxicity increases;

the introduction of unsaturated bonds and halogens has the same effect;

the formation of the hydrated form of aldehyde leads to a decrease in toxicity. But the ability to form a stable hydrate form is manifested only in chlorinated aldehydes. Thus, formaldehyde is a protoplasmic poison, used for disinfection, acetaldehyde and chloral are not used in medicine due to their high toxicity, and chloral hydrate is a drug used as a sleeping pill and sedative.

The strength of the narcotic (pharmacological) effect and toxicity increased from formaldehyde to acetaldehyde and chloral. The formation of a hydrate form (chloral hydrate) can dramatically reduce toxicity while maintaining the pharmacological effect.

According to physical condition aldehydes may be gaseous (low molecular weight), liquids and solids. Low molecular weight ones have a sharp unpleasant odor, high molecular weight ones have a pleasant floral odor.

Chemical properties

Chemically, these are highly reactive substances, which is due to the presence of a carbonyl group in their molecule.

The high reactivity of aldehydes is explained by:

a) the presence of a polarized double bond

b) carbonyl dipole moment

c) the presence of a partial positive charge on the carbonyl carbon atom

σ -

σ + H

The double bond between C and O, unlike the double bond between two carbons, is highly polarized, since oxygen has a much higher electronegativity than carbon, and the electron density of the π bond is shifted towards oxygen. Such high polarization determines the electrophilic properties of the carbon of the carbonyl group and its ability to react with nucleophilic compounds (to enter into nucleophilic addition reactions). The oxygen group has nucleophilic properties.

Characteristic reactions are oxidation and nucleophilic addition

I. Oxidation reactions.

Aldehydeseasily oxidize. Oxidation of aldehydes to acids occurs under the influence how strongand weak oxidizing agents .

Many metals - silver, mercury, bismuth, copper - are reduced from solutions of their salts, especially in the presence of alkali. This distinguishes aldehydes from other organic compounds capable of oxidation - alcohols, unsaturated compounds, the oxidation of which requires stronger oxidizing agents. Consequently, the oxidation reactions of aldehydes with complexly bound cations of mercury, copper, and silver in an alkaline medium can be used to prove the authenticity of aldehydes.

I. 1 .Reactionwith ammonia solution of silver nitrate (silver mirror reaction) FS is recommended to confirm the authenticity of substances with an aldehyde group. It is based on the oxidation of aldehyde to acid and the reduction of Ag + to Ag↓.

AgNO 3 + 2NH 4 OH → NO 3 +2H 2 O

NSSON+ 2NO 3 + H 2 O → HCOONH 4 + 2Ag↓+ 2NH 4 NO 3 + NH 3

Formaldehyde, oxidizing to the ammonium salt of formic acid, reduces metallic silver, which is precipitatedon the walls of the test tube in the form shiny coating "mirror" or gray sediment.

I. 2. Reactionwith Fehling's reagent (a complex compound of copper (II) with potassium-sodium salt of tartaric acid). Aldehydes reduce the copper(II) compound to copper(I) oxide, A brick-red precipitate forms. Prepare before use).

Felling's reagent 1 - CuSO 4 solution

Felling's reagent 2 – alkaline solution of potassium-sodium salt of tartaric acid

When mixing 1:1 Felling's reagents 1 and 2 a blue copper complex compound is formed (II) with potassium-sodium tartaric acid:

blue coloring

When the aldehyde is added and heated, the blue color of the reagent disappears, and an intermediate product is formed - a yellow precipitate of copper (I) hydroxide, which immediately decomposes into a red precipitate of copper (I) oxide and water.

2KNa+ R- COH+2NaOH+ 2KOH→ R- COONa+4KNaC 4 H 4 O 6 + 2 CuOH ↓ +H2O

2 CuOH ↓ →Cu 2 O ↓ +H2O

Yellow sediment brick red sediment

The textbooks have a different general reaction scheme

I. 3. Reactionwith Nessler's reagent (alkaline solution of potassium tetraiodomercurate (II). Formaldehyde reduces the mercury ion to metallic mercury - a dark gray precipitate.

R-COH + K 2 +3KOH → R-COOK + 4KI + Hg↓ + 2H 2 O

(for the simplest aldehyde R=H)

Classification of aldehydes

According to the structure of the hydrocarbon radical:

Limit; For example:

Unlimited; For example:

Aromatic; For example:

Alicyclic; For example:

General formula of saturated aldehydes

Homologous series, isomerism, nomenclature

Aldehydes are isomeric to another class of compounds, ketones.

For example:

Aldehydes and ketones contain a carbonyl group ˃C=O and are therefore called carbonyl compounds.

Electronic structure of aldehyde molecules

The carbon atom of the aldehyde group is in a state of sp 2 hybridization, therefore all σ bonds in this group are located in the same plane. The clouds of p electrons forming a π bond are perpendicular to this plane and are easily displaced towards the more electronegative oxygen atom. Therefore, the C=O double bond (unlike the C=C double bond in alkenes) is highly polarized.

Physical properties

Chemical properties

Aldehydes are reactive compounds that undergo numerous reactions. Most characteristic of aldehydes:

a) addition reactions at the carbonyl group; HX type reagents are added as follows:

b) oxidation reactions of the C-H bond of the aldehyde group, resulting in the formation of carboxylic acids:

I. Addition reactions

1. Hydrogenation (primary alcohols are formed

2. Addition of alcohols (hemiacetals and acetals are formed)

In excess alcohol in the presence of HCl, hemiacetals are converted to acetals:

II. Oxidation reactions

1. The “silver mirror” reaction

Simplified:

This reaction is a qualitative reaction to the aldehyde group (a mirror coating of metallic silver is formed on the walls of the reaction vessel).

2. Reaction with copper(II) hydroxide

This reaction is also a qualitative reaction to the aldehyde group y (a red precipitate of Cu 2 O precipitates).

Formaldehyde is oxidized by various O-containing oxidizers, first to formic acid and then to H 2 CO 3 (CO 2 + H 2 O):

III. Di-, tri- and polymerization reactions

1. Aldol condensation

2. Trimerization of acetaldehyde

3. Polymerization of formaldehyde

During long-term storage of formaldehyde (40% aqueous solution of formaldehyde), polymerization occurs in it with the formation of a white paraform precipitate:

IV. Polycondensation reaction of formaldehyde with phenol

Characteristic chemical properties of saturated monohydric and polyhydric alcohols, phenol

Saturated monohydric and polyhydric alcohols

Alcohols (or alkanols) are organic substances whose molecules contain one or more hydroxyl groups ($—OH$ groups) connected to a hydrocarbon radical.

Based on the number of hydroxyl groups (atomicity), alcohols are divided into:

- monoatomic, for example:

$(CH_3-OH)↙(methanol(methyl alcohol))$ $(CH_3-CH_2-OH)↙(ethanol(ethyl alcohol))$

— dihydric (glycols), For example:

$(OH-CH_2-CH_2-OH)↙(ethanediol-1,2(ethylene glycol))$

$(HO-CH_2-CH_2-CH_2-OH)↙(propanediol-1,3)$

— triatomic, For example:

Based on the nature of the hydrocarbon radical, the following alcohols are distinguished:

— limit containing only saturated hydrocarbon radicals in the molecule, for example:

— unlimited containing multiple (double and triple) bonds between carbon atoms in the molecule, for example:

$(CH_2=CH-CH_2-OH)↙(propen-2-ol-1 (allylic alcohol))$

— aromatic, i.e. alcohols containing a benzene ring and a hydroxyl group in the molecule, connected to each other not directly, but through carbon atoms, for example:

Organic substances containing hydroxyl groups in the molecule, connected directly to the carbon atom of the benzene ring, differ significantly in chemical properties from alcohols and therefore are classified as an independent class of organic compounds - phenols. For example:

There are also polyatomic (polyhydric) alcohols containing more than three hydroxyl groups in the molecule. For example, the simplest hexahydric alcohol hexaol (sorbitol):

Nomenclature and isomerism

When forming the names of alcohols, a generic suffix is ​​added to the name of the hydrocarbon corresponding to the alcohol -ol. The numbers after the suffix indicate the position of the hydroxyl group in the main chain, and the prefixes di-, tri-, tetra- etc. - their number:

In the numbering of carbon atoms in the main chain, the position of the hydroxyl group takes precedence over the position of multiple bonds:

Starting from the third member of the homologous series, alcohols exhibit isomerism of the position of the functional group (propanol-1 and propanol-2), and from the fourth, isomerism of the carbon skeleton (butanol-1, 2-methylpropanol-1). They are also characterized by interclass isomerism - alcohols are isomeric to ethers:

$(CH_3-CH_2-OH)↙(ethanol)$ $(CH_3-O-CH_3)↙(dimethyl ether)$

alcohols

Physical properties.

Alcohols can form hydrogen bonds both between alcohol molecules and between alcohol and water molecules.

Hydrogen bonds occur when a partially positively charged hydrogen atom of one alcohol molecule interacts with a partially negatively charged oxygen atom of another molecule. It is thanks to hydrogen bonds between molecules that alcohols have boiling points that are abnormally high for their molecular weight. Thus, propane with a relative molecular weight of $44$ is a gas under normal conditions, and the simplest of alcohols, methanol, with a relative molecular weight of $32$, is a liquid under normal conditions.

The lower and middle members of a series of saturated monohydric alcohols, containing from $1$ to $11$ carbon atoms, are liquids. Higher alcohols (starting from $C_(12)H_(25)OH$) are solids at room temperature. Lower alcohols have a characteristic alcoholic odor and pungent taste; they are highly soluble in water. As the hydrocarbon radical increases, the solubility of alcohols in water decreases, and octanol no longer mixes with water.

Chemical properties.

The properties of organic substances are determined by their composition and structure. Alcohols confirm the general rule. Their molecules include hydrocarbon and hydroxyl radicals, so the chemical properties of alcohols are determined by the interaction and influence of these groups on each other. The properties characteristic of this class of compounds are due to the presence of a hydroxyl group.

1. Interaction of alcohols with alkali and alkaline earth metals. To identify the effect of a hydrocarbon radical on a hydroxyl group, it is necessary to compare the properties of a substance containing a hydroxyl group and a hydrocarbon radical, on the one hand, and a substance containing a hydroxyl group and not containing a hydrocarbon radical, on the other. Such substances can be, for example, ethanol (or other alcohol) and water. The hydrogen of the hydroxyl group of alcohol molecules and water molecules is capable of being reduced by alkali and alkaline earth metals (replaced by them):

$2Na+2H_2O=2NaOH+H_2$,

$2Na+2C_2H_5OH=2C_2H_5ONa+H_2$,

$2Na+2ROH=2RONa+H_2$.

2. Interaction of alcohols with hydrogen halides. Substitution of a hydroxyl group with a halogen leads to the formation of haloalkanes. For example:

$C_2H_5OH+HBr⇄C_2H_5Br+H_2O$.

This reaction is reversible.

3. Intermolecular dehydration of alcohols— splitting off a water molecule from two alcohol molecules when heated in the presence of water-removing agents:

As a result of intermolecular dehydration of alcohols, ethers. Thus, when ethyl alcohol is heated with sulfuric acid to a temperature from $100$ to $140°C$, diethyl (sulfuric) ether is formed:

4. Interaction of alcohols with organic and inorganic acids to form esters ( esterification reaction):

The esterification reaction is catalyzed by strong inorganic acids.

For example, when ethyl alcohol and acetic acid react, ethyl acetate is formed - ethyl acetate:

5. Intramolecular dehydration of alcohols occurs when alcohols are heated in the presence of water-removing agents to a higher temperature than the temperature of intermolecular dehydration. As a result, alkenes are formed. This reaction is due to the presence of a hydrogen atom and a hydroxyl group at adjacent carbon atoms. An example is the reaction of producing ethene (ethylene) by heating ethanol above $140°C in the presence of concentrated sulfuric acid:

6. Oxidation of alcohols usually carried out with strong oxidizing agents, for example, potassium dichromate or potassium permanganate in an acidic environment. In this case, the action of the oxidizing agent is directed to the carbon atom that is already bonded to the hydroxyl group. Depending on the nature of the alcohol and the reaction conditions, various products can be formed. Thus, primary alcohols are oxidized first to aldehydes, and then in carboxylic acids:

The oxidation of secondary alcohols produces ketones:

Tertiary alcohols are quite resistant to oxidation. However, under harsh conditions (strong oxidizing agent, high temperature), oxidation of tertiary alcohols is possible, which occurs with the rupture of carbon-carbon bonds closest to the hydroxyl group.

7. Dehydrogenation of alcohols. When alcohol vapor is passed at $200-300°C over a metal catalyst, such as copper, silver or platinum, primary alcohols are converted into aldehydes, and secondary alcohols into ketones:

The presence of several hydroxyl groups in the alcohol molecule at the same time determines the specific properties polyhydric alcohols, which are capable of forming water-soluble bright blue complex compounds when interacting with a freshly prepared precipitate of copper (II) hydroxide. For ethylene glycol we can write:

Monohydric alcohols are not able to enter into this reaction. Therefore, it is a qualitative reaction to polyhydric alcohols.

Phenol

Structure of phenols

The hydroxyl group in molecules of organic compounds can be associated with the aromatic ring directly, or can be separated from it by one or more carbon atoms. It can be expected that, depending on this property, substances will differ significantly from each other due to the mutual influence of groups of atoms. Indeed, organic compounds containing the aromatic radical phenyl $C_6H_5$—, directly bonded to the hydroxyl group, exhibit special properties that differ from the properties of alcohols. Such compounds are called phenols.

Phenols are organic substances whose molecules contain a phenyl radical associated with one or more hydroxo groups.

Just like alcohols, phenols are classified according to their atomicity, i.e. by the number of hydroxyl groups.

Monohydric phenols contain one hydroxyl group in the molecule:

Polyhydric phenols contain more than one hydroxyl group in molecules:

There are other polyhydric phenols containing three or more hydroxyl groups on the benzene ring.

Let's take a closer look at the structure and properties of the simplest representative of this class - phenol $C_6H_5OH$. The name of this substance formed the basis for the name of the entire class - phenols.

Physical and chemical properties.

Physical properties.

Phenol is a solid, colorless, crystalline substance, $t°_(pl.)=43°C, t°_(boiling)=181°C$, with a sharp characteristic odor. Poisonous. Phenol is slightly soluble in water at room temperature. An aqueous solution of phenol is called carbolic acid. If it comes into contact with the skin, it causes burns, so phenol must be handled with care!

Chemical properties.

Acidic properties. As already mentioned, the hydrogen atom of the hydroxyl group is acidic in nature. The acidic properties of phenol are more pronounced than those of water and alcohols. Unlike alcohols and water, phenol reacts not only with alkali metals, but also with alkalis to form phenolates:

However, the acidic properties of phenols are less pronounced than those of inorganic and carboxylic acids. For example, the acidic properties of phenol are approximately $3000$ times weaker than those of carbonic acid. Therefore, by passing carbon dioxide through an aqueous solution of sodium phenolate, free phenol can be isolated:

Adding hydrochloric or sulfuric acid to an aqueous solution of sodium phenolate also leads to the formation of phenol:

Qualitative reaction to phenol.

Phenol reacts with iron (III) chloride to form an intensely purple complex compound.

This reaction allows it to be detected even in very limited quantities. Other phenols containing one or more hydroxyl groups on the benzene ring also produce bright blue-violet colors when reacted with iron(III) chloride.

Reactions of the benzene ring.

The presence of a hydroxyl substituent greatly facilitates the occurrence of electrophilic substitution reactions in the benzene ring.

1. Bromination of phenol. Unlike benzene, the bromination of phenol does not require the addition of a catalyst (iron (III) bromide).

In addition, the interaction with phenol occurs selectively: bromine atoms are directed to ortho- and para positions, replacing the hydrogen atoms located there. The selectivity of substitution is explained by the features of the electronic structure of the phenol molecule discussed above.

Thus, when phenol reacts with bromine water, a white precipitate is formed 2,4,6-tribromophenol:

This reaction, like the reaction with iron (III) chloride, serves for the qualitative detection of phenol.

2. Nitration of phenol also occurs more easily than benzene nitration. The reaction with dilute nitric acid occurs at room temperature. As a result, a mixture is formed ortho- And pair- isomers of nitrophenol:

When concentrated nitric acid is used, an explosive is formed - 2,4,6-trinitrophenol(picric acid):

3. Hydrogenation of the aromatic core of phenol in the presence of a catalyst occurs easily:

4.Polycondensation of phenol with aldehydes, in particular with formaldehyde, occurs with the formation of reaction products - phenol-formaldehyde resins and solid polymers.

The interaction of phenol with formaldehyde can be described by the following scheme:

You probably noticed that “mobile” hydrogen atoms are retained in the dimer molecule, which means that further continuation of the reaction is possible with a sufficient number of reagents:

Reaction polycondensation, those. the polymer production reaction, which occurs with the release of a low-molecular-weight by-product (water), can continue further (until one of the reagents is completely consumed) with the formation of huge macromolecules. The process can be described by the overall equation:

The formation of linear molecules occurs at ordinary temperatures. Carrying out this reaction when heated leads to the fact that the resulting product has a branched structure, it is solid and insoluble in water. As a result of heating a linear phenol-formaldehyde resin with an excess of aldehyde, hard plastic masses with unique properties are obtained. Polymers based on phenol-formaldehyde resins are used for the manufacture of varnishes and paints, plastic products that are resistant to heating, cooling, water, alkalis and acids, and have high dielectric properties. The most critical and important parts of electrical appliances, power unit housings and machine parts, and the polymer base of printed circuit boards for radio devices are made from polymers based on phenol-formaldehyde resins. Adhesives based on phenol-formaldehyde resins are capable of reliably connecting parts of a wide variety of natures, maintaining the highest joint strength over a very wide temperature range. This glue is used to attach the metal base of lighting lamps to a glass bulb. Now you understand why phenol and products based on it are widely used.

Characteristic chemical properties of aldehydes, saturated carboxylic acids, esters

Aldehydes and ketones

Aldehydes are organic substances whose molecules contain a carbonyl group , connected to a hydrogen atom and a hydrocarbon radical.

The general formula of aldehydes is:

In the simplest aldehyde, formaldehyde, the role of a hydrocarbon radical is played by the second hydrogen atom:

A carbonyl group bonded to a hydrogen atom is called aldehydic:

Organic substances in whose molecules a carbonyl group is linked to two hydrocarbon radicals are called ketones.

Obviously, the general formula for ketones is:

The carbonyl group of ketones is called keto group.

In the simplest ketone, acetone, the carbonyl group is linked to two methyl radicals:

Nomenclature and isomerism

Depending on the structure of the hydrocarbon radical associated with the aldehyde group, saturated, unsaturated, aromatic, heterocyclic and other aldehydes are distinguished:

In accordance with the IUPAC nomenclature, the names of saturated aldehydes are formed from the name of an alkane with the same number of carbon atoms in the molecule using the suffix -al. For example:

The numbering of the carbon atoms of the main chain begins with the carbon atom of the aldehyde group. Therefore, the aldehyde group is always located at the first carbon atom, and there is no need to indicate its position.

Along with systematic nomenclature, trivial names of widely used aldehydes are also used. These names are usually derived from the names of carboxylic acids corresponding to aldehydes.

To name ketones according to systematic nomenclature, the keto group is designated by the suffix -He and a number that indicates the number of the carbon atom of the carbonyl group (numbering should start from the end of the chain closest to the keto group). For example:

Aldehydes are characterized by only one type of structural isomerism - isomerism of the carbon skeleton, which is possible with butanal, and for ketones - also isomerism of the position of the carbonyl group. In addition, they are characterized by interclass isomerism (propanal and propanone).

Trivial names and boiling points of some aldehydes.

Physical and chemical properties

Physical properties.

In an aldehyde or ketone molecule, due to the greater electronegativity of the oxygen atom compared to the carbon atom, the $C=O$ bond is highly polarized due to a shift in the electron density of the $π$ bond towards oxygen:

Aldehydes and ketones are polar substances with excess electron density on the oxygen atom. The lower members of the series of aldehydes and ketones (formaldehyde, acetaldehyde, acetone) are unlimitedly soluble in water. Their boiling points are lower than those of the corresponding alcohols. This is due to the fact that in the molecules of aldehydes and ketones, unlike alcohols, there are no mobile hydrogen atoms and they do not form associates due to hydrogen bonds. Lower aldehydes have a pungent odor; Aldehydes containing four to six carbon atoms in the chain have an unpleasant odor; Higher aldehydes and ketones have floral odors and are used in perfumery.

Chemical properties

The presence of an aldehyde group in a molecule determines the characteristic properties of aldehydes.

Recovery reactions.

Hydrogen addition to aldehyde molecules occurs via a double bond in the carbonyl group:

The product of hydrogenation of aldehydes is primary alcohols, and ketones are secondary alcohols.

Thus, when hydrogenating acetaldehyde on a nickel catalyst, ethyl alcohol is formed, and when hydrogenating acetone, propanol-2 is formed:

Hydrogenation of aldehydes - recovery reaction at which the oxidation state of the carbon atom included in the carbonyl group decreases.

Oxidation reactions.

Aldehydes can not only be reduced, but also oxidize. When oxidized, aldehydes form carboxylic acids. This process can be schematically represented as follows:

From propionic aldehyde (propanal), for example, propionic acid is formed:

Aldehydes are oxidized even by atmospheric oxygen and such weak oxidizing agents as an ammonia solution of silver oxide. In a simplified form, this process can be expressed by the reaction equation:

For example:

This process is more accurately reflected by the equations:

If the surface of the vessel in which the reaction is carried out has been previously degreased, then the silver formed during the reaction covers it with an even thin film. Therefore this reaction is called reaction "silver mirror". It is widely used for making mirrors, silvering decorations and Christmas tree decorations.

Freshly precipitated copper(II) hydroxide can also act as an oxidizing agent for aldehydes. Oxidizing the aldehyde, $Cu^(2+)$ is reduced to $Cu^+$. The copper (I) hydroxide $CuOH$ formed during the reaction immediately decomposes into red copper (I) oxide and water:

This reaction, like the “silver mirror” reaction, is used to detect aldehydes.

Ketones are not oxidized either by atmospheric oxygen or by such a weak oxidizing agent as an ammonia solution of silver oxide.

Individual representatives of aldehydes and their significance

Formaldehyde(methanal, formicaldehyde$HCHO$ ) - a colorless gas with a pungent odor and a boiling point of $-21C°$, highly soluble in water. Formaldehyde is poisonous! A solution of formaldehyde in water ($40%$) is called formaldehyde and is used for disinfection. In agriculture, formaldehyde is used to treat seeds, and in the leather industry - for treating leather. Formaldehyde is used to produce methenamine, a medicinal substance. Sometimes methenamine compressed in the form of briquettes is used as fuel (dry alcohol). A large amount of formaldehyde is consumed in the production of phenol-formaldehyde resins and some other substances.

Acetaldehyde(ethanal, acetaldehyde$CH_3CHO$ ) - a liquid with a sharp unpleasant odor and a boiling point of $21°C$, highly soluble in water. Acetic acid and a number of other substances are produced from acetaldehyde on an industrial scale; it is used for the production of various plastics and acetate fiber. Acetaldehyde is poisonous!

Carboxylic acids

Substances containing one or more carboxyl groups in a molecule are called carboxylic acids.

Group of atoms called carboxyl group, or carboxyl.

Organic acids containing one carboxyl group in the molecule are monobasic.

The general formula of these acids is $RCOOH$, for example:

Carboxylic acids containing two carboxyl groups are called dibasic. These include, for example, oxalic and succinic acids:

There are also polybasic carboxylic acids containing more than two carboxyl groups. These include, for example, tribasic citric acid:

Depending on the nature of the hydrocarbon radical, carboxylic acids are divided into saturated, unsaturated, aromatic.

Saturated, or saturated, carboxylic acids are, for example, propanoic (propionic) acid:

or the already familiar succinic acid.

It is obvious that saturated carboxylic acids do not contain $π$ bonds in the hydrocarbon radical. In molecules of unsaturated carboxylic acids, the carboxyl group is associated with an unsaturated, unsaturated hydrocarbon radical, for example, in molecules of acrylic (propene) $CH_2=CH—COOH$ or oleic $CH_3—(CH_2)_7—CH=CH—(CH_2)_7—COOH $ and other acids.

As can be seen from the formula of benzoic acid, it is aromatic, since it contains an aromatic (benzene) ring in the molecule:

Nomenclature and isomerism

The general principles of the formation of the names of carboxylic acids, as well as other organic compounds, have already been discussed. Let us dwell in more detail on the nomenclature of mono- and dibasic carboxylic acids. The name of a carboxylic acid is derived from the name of the corresponding alkane (alkane with the same number of carbon atoms in the molecule) with the addition of the suffix -ov-, endings -and I and the words acid. The numbering of carbon atoms begins with the carboxyl group. For example:

The number of carboxyl groups is indicated in the name by prefixes di-, tri-, tetra-:

Many acids also have historically established, or trivial, names.

Names of carboxylic acids.

Chemical formula	Systematic name of acid	Trivial name for acid
$H—COOH$	Methane	Ant
$CH_3—COOH$	Ethanova	Vinegar
$CH_3—CH_2—COOH$	Propane	Propionic
$CH_3—CH_2—CH_2—COOH$	Butane	Oily
$CH_3—CH_2—CH_2—CH_2—COOH$	Pentanic	Valerian
$CH_3—(CH_2)_4—COOH$	Hexane	Nylon
$CH_3—(CH_2)_5—COOH$	Heptane	Enanthic
$NOOC—COOH$	Ethanedium	Sorrel
$NOOC—CH_2—COOH$	Propanedium	Malonovaya
$NOOC—CH_2—CH_2—COOH$	Butanediovy	Amber

After getting acquainted with the diverse and interesting world of organic acids, we will consider in more detail the saturated monobasic carboxylic acids.

It is clear that the composition of these acids is expressed by the general formula $C_nH_(2n)O_2$, or $C_nH_(2n+1)COOH$, or $RCOOH$.

Physical and chemical properties

Physical properties.

Lower acids, i.e. acids with a relatively small molecular weight, containing up to four carbon atoms per molecule, are liquids with a characteristic pungent odor (remember the smell of acetic acid). Acids containing from $4$ to $9$ carbon atoms are viscous oily liquids with an unpleasant odor; containing more than $9$ carbon atoms per molecule - solids that do not dissolve in water. The boiling points of saturated monobasic carboxylic acids increase with increasing number of carbon atoms in the molecule and, consequently, with increasing relative molecular weight. For example, the boiling point of formic acid is $100.8°C$, acetic acid is $118°C$, and propionic acid is $141°C$.

The simplest carboxylic acid is formic $HCOOH$, having a small relative molecular weight $(M_r(HCOOH)=46)$, under normal conditions it is a liquid with a boiling point of $100.8°C$. At the same time, butane $(M_r(C_4H_(10))=58)$ under the same conditions is gaseous and has a boiling point of $-0.5°C$. This discrepancy between boiling points and relative molecular weights is explained by the formation of carboxylic acid dimers, in which two acid molecules are linked by two hydrogen bonds:

The occurrence of hydrogen bonds becomes clear when considering the structure of carboxylic acid molecules.

Molecules of saturated monobasic carboxylic acids contain a polar group of atoms - carboxyl and a practically non-polar hydrocarbon radical. The carboxyl group is attracted to water molecules, forming hydrogen bonds with them:

Formic and acetic acids are unlimitedly soluble in water. It is obvious that with an increase in the number of atoms in a hydrocarbon radical, the solubility of carboxylic acids decreases.

Chemical properties.

The general properties characteristic of the class of acids (both organic and inorganic) are due to the presence in the molecules of a hydroxyl group containing a strong polar bond between hydrogen and oxygen atoms. Let us consider these properties using the example of water-soluble organic acids.

1. Dissociation with the formation of hydrogen cations and anions of the acid residue:

$CH_3-COOH⇄CH_3-COO^(-)+H^+$

More accurately, this process is described by an equation that takes into account the participation of water molecules in it:

$CH_3-COOH+H_2O⇄CH_3COO^(-)+H_3O^+$

The dissociation equilibrium of carboxylic acids is shifted to the left; the vast majority of them are weak electrolytes. However, the sour taste of, for example, acetic and formic acids is due to dissociation into hydrogen cations and anions of acidic residues.

It is obvious that the presence of “acidic” hydrogen in the molecules of carboxylic acids, i.e. hydrogen of the carboxyl group, due to other characteristic properties.

2. Interaction with metals, standing in the electrochemical voltage series up to hydrogen: $nR-COOH+M→(RCOO)_(n)M+(n)/(2)H_2$

Thus, iron reduces hydrogen from acetic acid:

$2CH_3-COOH+Fe→(CH_3COO)_(2)Fe+H_2$

3. Interaction with basic oxides with the formation of salt and water:

$2R-COOH+CaO→(R-COO)_(2)Ca+H_2O$

4. Interaction with metal hydroxides with the formation of salt and water (neutralization reaction):

$R—COOH+NaOH→R—COONa+H_2O$,

$2R—COOH+Ca(OH)_2→(R—COO)_(2)Ca+2H_2O$.

5. Interaction with salts of weaker acids with the formation of the latter. Thus, acetic acid displaces stearic acid from sodium stearate and carbonic acid from potassium carbonate:

$CH_3COOH+C_(17)H_(35)COONa→CH_3COONa+C_(17)H_(35)COOH↓$,

$2CH_3COOH+K_2CO_3→2CH_3COOK+H_2O+CO_2$.

6. Interaction of carboxylic acids with alcohols with the formation of esters - esterification reaction (one of the most important reactions characteristic of carboxylic acids):

The interaction of carboxylic acids with alcohols is catalyzed by hydrogen cations.

The esterification reaction is reversible. The equilibrium shifts toward ester formation in the presence of dewatering agents and when the ester is removed from the reaction mixture.

In the reverse reaction of esterification, called ester hydrolysis (the reaction of an ester with water), an acid and an alcohol are formed:

It is obvious that reacting with carboxylic acids, i.e. Polyhydric alcohols, for example glycerol, can also enter into an esterification reaction:

All carboxylic acids (except formic acid), along with the carboxyl group, contain a hydrocarbon residue in their molecules. Of course, this cannot but affect the properties of acids, which are determined by the nature of the hydrocarbon residue.

7. Multiple addition reactions- they contain unsaturated carboxylic acids. For example, the hydrogen addition reaction is hydrogenation. For an acid containing one $π$ bond in the radical, the equation can be written in general form:

$C_(n)H_(2n-1)COOH+H_2(→)↖(catalyst)C_(n)H_(2n+1)COOH.$

Thus, when oleic acid is hydrogenated, saturated stearic acid is formed:

$(C_(17)H_(33)COOH+H_2)↙(\text"oleic acid"))(→)↖(catalyst)(C_(17)H_(35)COOH)↙(\text"stearic acid") $

Unsaturated carboxylic acids, like other unsaturated compounds, add halogens via a double bond. For example, acrylic acid decolorizes bromine water:

$(CH_2=CH—COOH+Br_2)↙(\text"acrylic (propenoic) acid")→(CH_2Br—CHBr—COOH)↙(\text"2,3-dibromopropanoic acid").$

8. Substitution reactions (with halogens)- saturated carboxylic acids are capable of entering into them. For example, by reacting acetic acid with chlorine, various chlorinated acids can be obtained:

$CH_3COOH+Cl_2(→)↖(P(red))(CH_2Cl-COOH+HCl)↙(\text"chloroacetic acid")$,

$CH_2Cl-COOH+Cl_2(→)↖(P(red))(CHCl_2-COOH+HCl)↙(\text"dichloroacetic acid")$,

$CHCl_2-COOH+Cl_2(→)↖(P(red))(CCl_3-COOH+HCl)↙(\text"trichloroacetic acid")$

Individual representatives of carboxylic acids and their significance

Ant(methane) acid HTSOOKH- a liquid with a pungent odor and a boiling point of $100.8°C$, highly soluble in water. Formic acid is poisonous Causes burns upon contact with skin! The stinging fluid secreted by ants contains this acid. Formic acid has disinfectant properties and therefore finds its use in the food, leather and pharmaceutical industries, and medicine. It is used in dyeing fabrics and paper.

Vinegar (ethane)acid $CH_3COOH$ is a colorless liquid with a characteristic pungent odor, miscible with water in any ratio. Aqueous solutions of acetic acid are sold under the name vinegar ($3-5% solution) and vinegar essence ($70-80% solution) and are widely used in the food industry. Acetic acid is a good solvent for many organic substances and is therefore used in dyeing, tanning, and the paint and varnish industry. In addition, acetic acid is a raw material for the production of many technically important organic compounds: for example, substances used to control weeds - herbicides - are obtained from it.

Acetic acid is the main component wine vinegar, the characteristic smell of which is due precisely to it. It is a product of ethanol oxidation and is formed from it when wine is stored in air.

The most important representatives of higher saturated monobasic acids are palmitic$C_(15)H_(31)COOH$ and stearic$C_(17)H_(35)COOH$ acid. Unlike lower acids, these substances are solid and poorly soluble in water.

However, their salts - stearates and palmitates - are highly soluble and have a detergent effect, which is why they are also called soaps. It is clear that these substances are produced on a large scale. Of the unsaturated higher carboxylic acids, the most important is oleic acid$C_(17)H_(33)COOH$, or $CH_3 - (CH_2)_7 - CH=CH -(CH_2)_7COOH$. It is an oil-like liquid without taste or odor. Its salts are widely used in technology.

The simplest representative of dibasic carboxylic acids is oxalic (ethanedioic) acid$HOOC—COOH$, the salts of which are found in many plants, such as sorrel and sorrel. Oxalic acid is a colorless crystalline substance that is highly soluble in water. It is used for polishing metals, in the woodworking and leather industries.

Esters

When carboxylic acids react with alcohols (esterification reaction), they form esters:

This reaction is reversible. The reaction products can interact with each other to form the starting materials - alcohol and acid. Thus, the reaction of esters with water—ester hydrolysis—is the reverse of the esterification reaction. The chemical equilibrium established when the rates of forward (esterification) and reverse (hydrolysis) reactions are equal can be shifted towards the formation of ester by the presence of water-removing agents.

Fats- derivatives of compounds that are esters of glycerol and higher carboxylic acids.

All fats, like other esters, undergo hydrolysis:

When hydrolysis of fat is carried out in an alkaline environment $(NaOH)$ and in the presence of soda ash $Na_2CO_3$, it proceeds irreversibly and leads to the formation not of carboxylic acids, but of their salts, which are called soaps. Therefore, the hydrolysis of fats in an alkaline environment is called saponification.