Obtaining carboxylic acid from alcohol. Chemical properties of carboxylic acids. Laboratory methods for producing carboxylic acids

Chemical compoundswhich consist in the carboxyl group of COOH, received carboxylic acids from scientists. There are a large number of items of these compounds. They are classified by different parameters, for example, by the number of functional groups, the presence of an aromatic ring and so on.

The structure of carboxylic acids

As already mentioned, in order for the acid to be carboxy, it should have a carboxyl group, which, in turn, has two functional parts: hydroxyl and carbonyl. Their interaction is provided by its functional combination of one carbon atom with two oxygen. Chemical properties carboxylic acids Depend on how this structure has this group.

Due to the carboxyl group these organic compounds can be called acids. Their properties are caused by the increased ability of the hydrogen ion H + attract to oxygen, additionally polarizing communication O-H. Also, due to this property, organic acids are able to dissociate in aqueous solutions. The ability to dissolve decreases inversely proportionally molecular weight Acids.

Varieties of carboxylic acids

Chemists allocate several groups of organic acids.

Mono-based carboxylic acids consist of a carbon skeleton and only one functional carboxyl group. Each schoolboy knows the chemical properties of carboxylic acids. Grade 10 curriculum Chemistry includes directly the study of the properties of mono-abnormous acids. Buses and multi-axis acids have two and more carboxyl groups in their structure, respectively.

Also, according to the presence or absence of double and triple bonds in the molecule, there are unsaturated and saturated carboxylic acids. Chemical properties and their differences will be discussed below.

If the organic acid has a substituted atom as part of a radical, then the name of the substituent group is included in its name. So, if the hydrogen atom is substituted with a halogen, then the name of the halogen will be present in the name of the acid. The same changes will undergo the name if it will be replaced with an aldehyde, hydroxyl or amino group.

Isomerius of organic carboxylic acids

The basis of obtaining soap is the reaction of the synthesis of the esters of the above acids with a potassium or sodium salt.

Methods for producing carboxylic acids

The methods and methods of obtaining acids with the COOH group there are many, but the following are most often applied:

1. Selection of natural substances (fats and other things).
2. Oxidation of monospirts or connections with a COH group (aldehydes): ROH (RCOH) [O] R-COOH.
3. Hydrolysis of trigallagens in alkali with intermediate production of monospirt: RCl3 + NaOH \u003d (ROH + 3NACL) \u003d RCOOH + H2O.
4. Washing or hydrolysis of esters of acid and alcohol (esters): R-coor "+ NaOH \u003d (R-Coona + R" OH) \u003d R-COOH + NaCl.
5. Oxidation of alkanes permanganate (rigid oxidation): R \u003d CH2 [O], (KMNO4) RCOOH.

The value of carboxylic acids for humans and industry

Chemical properties of carboxylic acids have great importance For human vital activity. They are extremely necessary for the body, as large quantities are contained in each cell. The metabolism of fats, proteins and carbohydrates always passes through the stage, on which one or another carboxylic acid is obtained.

In addition, carboxylic acids are used when creating drugs. No pharmaceutical industry can exist without applying the properties of organic acids.

An important role of the compound with the carboxyl group is also played in the cosmetic industry. Fat synthesis for the subsequent manufacture of soap, detergents and household chemicals is based on esterification reaction with carboxylic acid.

Chemical properties of carboxylic acids are reflected in human vital activity. They are of great importance for human organismSince large quantities are contained in each cell. The metabolism of fats, proteins and carbohydrates always passes through the stage, on which one or another carboxylic acid is obtained.

Carboxylic acids Called the compounds containing a carboxyl group:

Carboxylic acids distinguish:

• monolayer carboxylic acids;
• two-axis (dicarboxylic) acids (2 groups Soon).

Depending on the structure, carboxylic acids distinguish:

• aliphatic;
• alicyclic;
• aromatic.

Examples of carboxylic acids.

Obtaining carboxylic acids.

1. Oxidation of primary alcohols permanganate potassium and dichromat potassium:

2. Gibribs of halogen-substituted hydrocarbons containing 3 atoms halogen One carbon atom:

3. Preparation of carboxylic acids from cyanides:

When heated, nitrile is hydrolyzed to form ammonium acetate:

When acidifying which the acid falls:

4. Use of Grignar reagents:

5. Hydrolysis of esters:

6. Hydrolysis of acid anhydrides:

7. Specific methods for producing carboxylic acids:

Formic acid is obtained when heated carbon oxide (II) With powdered sodium hydroxide under pressure:

Acetic acid is obtained by catalytic oxidation of butane air oxygen:

Benzoic acid is obtained by oxidation of monosightened homologs with a solution of potassium permanganate:

Reaction canniciaro. Benzaldehyde is treated with a 40-60% sodium hydroxide solution at room temperature.

Chemical properties of carboxylic acids.

In an aqueous solution, carboxylic acids dissociate:

Equilibrium shifted to the left, because Carboxylic acids are weak.

The substituents affect the acidity due to the inductive effect. Such substituents delay the electronic density on themselves and they arise a negative inductive effect (-i). Pulling electron density leads to an increase in acid acidity. Electroneal substituents create a positive inductive charge.

1. The formation of salts. Response with the main oxides, salts of weak acids and active metals:

Carboxylic acids - weak, because Mineralic acids displace them from the appropriate salts:

2. Formation of functional carboxylic acid derivatives:

3. Difficult ethers when heating acid with alcohol in presence sulfuric acid - The response of esterification:

4. Education of amides, nitriles:

3. Acid properties are caused by the presence of a hydrocarbon radical. If the reaction proceeds into the presence of red phosphorus, it forms the following product:

4. Reaction of attachment.

8. Decarboxylation. The reaction is carried out by alkali with alkaline metal carboxylic salt:

9. Two-axis acid easily clears CO 2 When heated:

Additional materials on the topic: Carboxylic acids.

The formation of halolancans in the interaction of alcohols with halogen hydrogen - reversible reaction. Therefore, it is clear that alcohols can be obtained at hydrolysis Halogenellanov - Reactions of these compounds with water:

Multiatomic alcohols can be obtained by hydrolysis of halolanelleans containing more than one halogen atom in the molecule. For example:

Hydration alkenes

Hydration alkenes - Attachment of water on π - communication of alken molecules, for example:

Propenate hydration leads in accordance with the Rule of Markovnikov to form a secondary alcohol - propanol-2:

Hydrogenation of aldehydes and ketones

The oxidation of alcohols in mild conditions leads to the formation of aldehydes or ketones. Obviously, alcohols can be obtained during hydrogenation (reduction of hydrogen, hydrogen accession) aldehydes and ketones:

Oxidation of alkenes

Glycols, as already noted, can be obtained by oxidizing alkenes with aqueous solution of potassium permanganate. For example, ethylene glycol (ethandiol-1,2) is formed when ethylene oxidation (ethen):

Specific methods for obtaining alcohols

1. Some alcohols are obtained characteristic only for them in ways. So, methanol in industry get hydrogen react with carbon oxide(Ii) (carbon monoxide) at elevated pressure and high temperatures On the surface of the catalyst (zinc oxide):

The mixture of carbon monoxide and hydrogen, which is also necessary for this reaction, also called Synthesis Gas, is obtained by passing water vapor over hot coal:

2. Glucose fermentation. This method of producing ethyl (wine) alcohol is known to man from ancient times:

The main methods of obtaining oxygen-containing compounds (alcohols) are: hydrolysis halogen alcohol, hydration of alkenes, hydrogenation of aldehydes and ketones, oxidation of alkenes, as well as obtaining methanol from "synthesis gas" and fermentation of sugar substances.

Methods for obtaining aldehydes and ketones

1. Aldehydes and ketones can be obtained oxidation or dehydrization of alcohol. With oxidation or dehydrogenation of primary alcohols, aldehydes can be obtained, and secondary alcohols - ketones:

3CH 3 -CH 2 OH + K 2 CR 2 O 7 + 4H 2 SO 4 \u003d 3CHO 3 -CHO + K 2 SO 4 + CR 2 (SO 4) 3 + 7H 2 O

2. Kucherov's reaction. From acetylene as a result of the reaction, acetic aldehyde is obtained, from acetylene homologs - ketones:

3. When heating calcium or barium salts of carboxylic acids Reta and metal carbonate are formed:

Methods for producing carboxylic acids

1. Carboxylic acids can be obtained oxidation of primary alcohols or aldehydes:

3CH 3 -CH 2 OH + 2K 2 CR 2 O 7 + 8H 2 SO 4 \u003d 3CH 3 -COOH + 2K 2 SO 4 + 2Cr 2 (SO 4) 3 + 11H 2 O

5CH 3 -Cho + 2KMNO 4 + 3H 2 SO 4 \u003d 5CH 3 -COOH + 2MNSO 4 + K 2 SO 4 + 3H 2 O,

3ch 3 -Cho + K 2 Cr 2 O 7 + 4H 2 SO 4 \u003d 3CH 3 -COOH + CR 2 (SO 4) 3 + K 2 SO 4 + 4H 2 O,

CH 3 -CHO + 2OH CH 3 -COONH 4 + 2AG + 3NH 3 + H 2 O.

But when methanal oxidation with ammonia solution of silver oxide, ammonium carbonate is formed, and not formic acid:

Hchex + 4OH \u003d (NH 4) 2 CO 3 + 4AG + 6NH 3 + 2H 2 O.

2. Aromatic carboxylic acids are formed when oxidation of homologues benzene.:

5C 6 H 5 -CH 3 + 6KMNO 4 + 9H 2 SO 4 \u003d 5C 6 H 5 COOH + 6MNSO 4 + 3K 2 SO 4 + 14H 2 O,

5C 6 H 5 -C 2 H 5 + 12KMNO 4 + 18H 2 SO 4 \u003d 5C 6 H 5 COOH + 5CO 2 + 12MNSO 4 + 6K 2 SO 4 + 28H 2 O,

C 6 H 5 -CH 3 + 2KMNO 4 \u003d C 6 H 5 Cook + 2MNO 2 + KOH + H 2 O

3. Hydrolysis of various derivatives of carbon acidalso leads to acids. So, with hydrolysis of the ester, alcohol and carboxylic acid are formed. The responses of esterification and hydrolysis catalyzed by acid are reversible:

4. Hydrolysis of ester Under the influence aquatic solution Alkali proceeds irreversible, in this case it is not formed from the ester, and its salt is formed.

Almost everyone has vinegar. And most people know that its foundation is but what is it from a chemical point of view? What other this series exist and what are their characteristics? Let's try to understand this issue and explore the limit monasone carboxylic acids. Especially since the life applies not only acetic, but also some others, and the derivatives of these acids are generally frequent guests in every home.

Class of carboxylic acids: general characteristics

From the point of view of chemistry science, this class of compounds include oxygen-containing molecules that have a special grouping of atoms - a carboxyl functional group. It has the appearance of -son. Thus, the general formula that all limiting monosular carboxylic acids have, looks like this: R-COOH, where R is a particle-radical, which may include any number of carbon atoms.

According to this, the definition of this class of compounds can be given. Carboxylic acids are organic oxygen-containing molecules, which includes one or more functional groups -Conoons - carboxyl groups.

The fact that these substances are subject to acids are explained by the mobility of the hydrogen atom in carboxyl. Electronic density is unevenly distributed, since oxygen is the electrone-negative group in the group. From this communication O-n Almost polarizes, and the hydrogen atom becomes extremely vulnerable. It is easily splitting, entering into chemical interactions. Therefore, acids in the respective indicators give a similar reaction:

Due to the hydrogen atom, carboxylic acids exhibit oxidative properties. However, the presence of other atoms allows them to recover, participate in many other interactions.

Classification

There are several main features that are divided into groups of carboxylic acids. The first of them is the nature of the radical. This factor is distinguished:

• Alicyclic acids. Example: Jinna.
• Aromatic. Example: benzoic.
• Aliphatic. Example: acetic, acrylic, oxal and others.
• Heterocyclic. Example: nicotine.

If we talk about bonds in the molecule, then two groups of acids can also be distinguished:

Also a sign of the classification can be the number of functional groups. So, allocate the following categories.

1. Monasual - Only one -Cone group. Example: ant, stearin, butanova, valerian and others.
2. Dubious - respectively, two groups -Oson. Example: Shanglevable, Malonic and others.
3. Multiment - Lemon, dairy and others.

History opening

Winemaking flourished with antiquity itself. And, as you know, one of its products is acetic acid. Therefore, the story of fame this class The compounds take their roots since Robert Boyle and Johanna Glauber. However, at the same time chemical nature These molecules found out for a long time failed.

After all, the views of the vitalists were dominated for a long time, who denied the possibility of the formation of organic matter without living beings. But already in 1670, D. Ray managed to receive the very first representative - methane or formic acid. He did it, heating in the flask of alive ants.

Later, the work of scientists of Burterus and Kolbe showed the possibility of synthesizing these compounds from organic substances (distillation of charcoal). As a result, acetic was obtained. Thus, carboxylic acids were studied ( physical properties, Building) and should be the beginning to open all other representatives of a number of aliphatic compounds.

Physical properties

Today, all their representatives studied in detail. For each of them you can find a characteristic in all respects, including the application in industry and in nature. We will look at what carboxylic acids, and other parameters represent themselves.

So, you can select several basic characteristic parameters.

1. If the number of carbon atoms in the chain does not exceed five, then it is sharp smelling, movable and volatile fluids. Above five - severe oily substances, even more - solid, paraffin-shaped.
2. The density of the first two representatives exceeds one. All other lighter water.
3. Boiling point: the greater the chain, the higher the indicator. The more branched structure, the lower.
4. The melting point: depends on the parity of the carbon atoms in the chain. Thoms are higher, in odd lower.
5. Water dissolves very well.
6. Capable to form strong hydrogen bonds.

Such features are explained by the symmetry of the structure, which means that the structure of the crystal lattice, its strength. The more simple and structured molecules, the higher the indicators that give carboxylic acids. The physical properties of these compounds allow to determine areas and methods of using them in industry.

Chemical properties

As we have already been designated above, these acids may show properties different. Reactions with their participation are important for industrial synthesis of many compounds. Denote the most important chemical properties that can show monosular carboxylic acid.

1. Dissociation: R-COOH \u003d RCOO - + H +.
2. It exists that is, interacts with the main oxides, as well as their hydroxides. With simple metals, it interacts according to the standard scheme (that is, only with those that cost to hydrogen in a row of stresses).
3. With more strong acids (inorganic) behaves like a basis.
4. It is capable of recovering to primary alcohol.
5. Special reaction - esterification. This is interaction with alcohols with the formation of a complex product - ether.
6. Decarboxylation reaction, i.e. the cleavage of the carbon dioxide molecule.
7. It is capable of interacting with halides of elements such as phosphorus and sulfur.

Obviously, how many carboxylic acids are multifaceted. Physical properties, as well as chemical, quite diverse. In addition, it should be said that in general the strength of all acids organic molecules Sladden weak compared to their inorganic colleagues. Their dissociation constants do not exceed 4.8.

Methods for getting

There are several basic ways to obtain limiting carboxylic acids.

1. In the laboratory, this is done by oxidation:

• alcohols;
• aldehydes;
• alkins;
• alkylbenzenes;
• destruction of alkenes.

2. Hydrolysis:

• esters;
• nitriles;
• amides;
• trigalleosalins.

4. In industry, the synthesis is carried out by oxidation of hydrocarbons with large number Carbon atoms in the chain. The process is carried out in several stages with the release of a plurality of by-products.

5. Some individual acids (formic, acetic, oil, valerian and other) are obtained by specific methods using natural ingredients.

Main compounds of limit carboxylic acids: salts

Carboxylic acid salts are important compounds used in industry. They are obtained as a result of the interaction of the latter with:

• metals;
• main oxides;
• alkalis;
• amphoteric hydroxides.

Especially important among them are those formed between alkaline metals Sodium and potassium and higher ultraic acids are palmitic, stearin. After all, products of such interaction - soap, liquid and solid.

Soap

So, if we are talking about a similar reaction: 2c 17 H 35 -COOH + 2NA \u003d 2C 17 H 35 Coona + H 2,

that the formed product is a sodium stearate - this is by nature an ordinary shopping soap used for laundry laundry.

If you replace the acid to the palmitic, and the metal on potassium, then the palmitate of potassium is the liquid soap for washing the hands. Therefore, it is safe to declare that carboxylic acid salts are actually important compounds of organic nature. Their industrial production and use is simply tremendous on their scale. If you imagine how much soap spends every person on earth, it is easy to imagine these scales.

The esters of carboxylic acids

A special group of compounds that has its place in the classification of organic substances. This class is formed by the reaction of carboxylic acids with alcohols. The name of such interactions is esterification reactions. General form Can be represented by the equation:

R, -COOH + R "-OH \u003d R, -COOR" + H 2 O.

The product with two radicals is ester. It is obvious that as a result of the reaction, carboxylic acid, alcohol, ester and water have undergone significant changes. Thus, hydrogen from the acid molecule goes in the form of a cation and occurs with a hydro-group, asleeping from alcohol. As a result, the water molecule is formed. The grouping remaining from the acid joins the radical from alcohol, forming a soluce of ester.

What are these reactions so important and what is the industrial importance of their products? The thing is that the esters are used as:

• nutritional supplements;
• aromatic additives;
• composite component of perfume;
• solvents;
• components of varnishes, paints, plastics;
• medicines and so on.

It is clear that their use areas are wide enough to justify the volume of production in industry.

Equity acid (acetic)

This is the limiting monosular carboxylic acid of an aliphatic series, which is one of the most common in the volume of production throughout the world. The formula of it is CH 3 coxy. It is obliged to be such a prevalence. After all, its use is extremely wide.

1. She happens to be food additive Under the E-260 code.
2. Used in the food industry for conservation.
3. It is used in medicine for drug synthesis.
4. Component in obtaining fragrant connections.
5. Solvent.
6. Member of the process of typography, dyeing fabrics.
7. The required component in the reactions of chemical syntheses of the set of substances.

In everyday life, its 80 percent solution is called acetic essence, and if you dilute it to 15%, it will be simply vinegar. Pure 100% acid is called ice acetic.

Formic acid

The very first and simple representative of this class. Formula - Nson. It is also a dietary supplement under the E-236 code. Her natural sources:

• ants and bees;
• nettle;
• needles;
• fruits.

Main areas of use:

Also in surgery, solutions of these acid are used as antiseptic agents.