Option 2 in chemistry. Copper(II) nitrate was calcined, and the resulting solid was dissolved in dilute sulfuric acid. The solution of the resulting salt was subjected to electrolysis. The substance released at the cathode was dissolved in concentrated nitric acid. Solution

Ethers (alkane oxides) can be thought of as compounds formed by replacing both hydrogen atoms of a water molecule with two alkyl radicals or replacing a hydroxyl alcohol with an alkyl radical.

Isomerism and nomenclature. The general formula of ethers is ROR(I) ((C n H 2 n +1) 2 O) or C n H 2 n +1 OC k H 2 k +1, where nk(R 1  OR 2) (II). The latter are often called mixed ethers, although (I) is a special case of (II).

Ethers are isomeric to alcohols (functional group isomerism). Here are examples of such connections:

H 3 C  ABOUT  CH 3 dimethyl ether; C 2 H 5 OH ethyl alcohol;

H 5 C 2  ABOUT  C 2 H 5 diethyl ether; C 4 H 9 OH butyl alcohol;

H 5 C 2  ABOUT  C 3 H 7 ethylpropyl ether; C 5 H 11 OH amyl alcohol.

In addition, isomerism of the carbon skeleton is common for ethers (methyl propyl ether and methyl isopropyl ether). Optically active ethers are few in number.

Methods for preparing ethers

1. Interaction of halogen derivatives with alcoholates (Williamson reaction).

C 2 H 5 ОNa+I  C 2 H 5 H 5 C 2  ABOUT  C 2 H 5 +NaI

2. Dehydration of alcohols in the presence of hydrogen ions as catalysts.

2C 2 H 5 OHH 5 C 2  ABOUT  C 2 H 5

3. Partial reaction to produce diethyl ether.

P first stage:

IN second stage:

Physical properties of ethers

The first two simplest representatives - dimethyl and methyl ethyl ethers - are gases under normal conditions, all the rest are liquids. Their boiling point is much lower than the corresponding alcohols. Thus, the boiling point of ethanol is 78.3C, and H 3 COCH 3 is 24C, respectively (C 2 H 5) 2 O is 35.6C. The point is that ethers are not capable of forming molecular hydrogen bonds, and, consequently, of molecule association.

Chemical properties of ethers

1. Interaction with acids.

(C 2 H 5) 2 O +HCl[(C 2 H 5) 2 OH + ]Cl  .

Ether plays the role of a base.

2. Acidolysis – interaction with strong acids.

H 5 C 2  ABOUT  C 2 H 5 + 2H 2 SO 4 2C 2 H 5 OSO 3 H

ethylsulfuric acid

H 5 C 2  ABOUT  C 2 H 5 +HIC 2 H 5 OH+ C 2 H 5 I

3. Interaction with alkali metals.

H 5 C 2  ABOUT  C 2 H 5 + 2NaC 2 H 5 ONa+ C 2 H 5 Na

Individual representatives

Ethyl ether (diethyl ether) is a colorless transparent liquid, slightly soluble in water. Mixes with ethyl alcohol in any ratio. T pl =116.3С, saturated vapor pressure 2.6610 4 Pa ​​(2.2С) and 5.3210 4 Pa ​​(17.9С). The cryoscopic constant is 1.79, the ebulioscopic constant is 1.84. Ignition temperature is 9.4С, forms an explosive mixture with air at 1.71 vol. % (lower limit) – 48.0 vol. % (upper limit). Causes rubber swelling. Widely used as a solvent, in medicine (inhalation anesthesia), addictive to humans, poisonous.

Esters of carboxylic acids Preparation of esters of carboxylic acids

1. Esterification of acids with alcohols.

Hydroxyl acid is released in water, while alcohol gives away only a hydrogen atom. The reaction is reversible; the same cations catalyze the reverse reaction.

2. Interaction of acid anhydrides with alcohols.

3. Interaction of acid halides with alcohols.

Some physical properties of esters are given in Table 12.

Table 12

Some physical properties of a number of esters

	Radical structure	Name			Density
		methyl formate
		ethyl formate
		methyl acetate
		ethyl acetate
		n-propyl acetate
		n-butyl acetate

Esters lower carboxylic acids and simple alcohols - liquids with a refreshing fruity odor. Used as flavoring agents for preparing drinks. Many ethers (ethyl acetate, butyl acetate) are widely used as solvents, especially for varnishes.

Esters are derivatives of carbonic or inorganic acids, in the molecule of which the hydrogen atom in the hydroxyl group is replaced by a radical. This structure determines chemical properties esters.

Species

Esters of carboxylic acids are divided into three general groups:

• fruity esters- liquids containing no more than eight carbon atoms (C 3 H 7 -COO-C 2 H 5 - ethyl ester of butyric acid)
• fats- liquid (oils) and solids, including 9-19 carbon atoms and containing glycerol and fatty acid residues;
• waxes- solids containing 15-45 carbon atoms.

Rice. 1. The structure of fat molecules.

Oils common in everyday life are mixtures consisting of glycerin and residues of various fatty acids.

Receipt

Esters are produced using an esterification reaction from alcohols and carboxylic acids:

CH 3 COOH + C 2 H 5 OH → CH 3 COOC 2 H 5 + H 2 O.

This is the most important reaction, which is reversible in a number of cases: interacting with water, the formed ester again decomposes into the initial substances.

Esters are also obtained by the interaction:

• anhydrides with alcohols:

  (CH 3 CO) 2 O + 2C 2 H 5 OH → 2CH 3 COOC 2 H 5 + H 2 O;

• salts of carboxylic acids with halogenated hydrocarbons:

  CH 3 (CH 2) 10 COONa + CH 3 Cl → CH 3 (CH 2) 10 COOCH 3 + NaCl;

• carboxylic acids to alkenes:

  CH 3 COOH + CH 2 =CH 2 → CH 3 COOCH 2 CH 3 + H 2 O.

During the esterification reaction, a hydrogen atom is removed from the alcohol molecule, and a hydroxyl atom is removed from the acid.

Chemical properties

The properties of esters and fats are due to the presence of the functional carboxyl group -COOH in the molecule. The main chemical properties of ethers are presented in the table.

Reaction	Description	Equation
Hydrolysis	The reverse reaction of esterification is splitting into aquatic environment for alcohol and acid. When heated with water in acidic environment decompose into acid and alcohol. Esters are “saponified” under the action of an alkali solution, forming an organic salt and alcohol. In this case the reaction is irreversible	CH 3 -C(O)-O-CH 2 -CH 2 -CH 3 (propyl ester of acetic acid) + H 2 O (H 2 SO 4 dil.) ↔ CH 3 COOH (acetic acid) + OH-CH 2 - CH 2 -CH 3 (propanol-1); CH3-C(O)-O-CH2-CH2-CH3 + H2O + NaOH CH3-C(O)-ONa + OH-CH2-CH2-CH3
Reduction (hydrogenation)	When hydrogen is added, complex alcohols are reduced to alcohols	CH 3 -COO-CH 2 -CH 3 (ethyl acetate) + 2H 2 → 2C 2 H 5 OH (ethanol)
Addition (halogenation)	The reaction is possible if there are double bonds in the molecule. Halogen atoms attach to bond breaking sites	CH 3 COOCH = CH 2 (vinyl ester of acetic acid) + Br 2 → Br-CH 2 -CH(Br)-COOH-CH 2
Substitution	When interacting with ammonia, the -SON group is replaced by an amino group. Amide and alcohol are formed	CH3-COO-CH3 (methyl acetate) + NH 3 → CH 3 -C(NH 2)=O (acetic acid amide) + CH 3 -OH (methanol)
	Upon complete combustion, it forms carbon dioxide and water	2CH 3 -COO-CH 3 + 7O 2 → 6CO 2 + 6H 2 O

Rice. 2. Scheme of saponification of fats.

Esters are used as flavoring agents in medicine, perfumery, food industry. They are found in berries, fruits, and beeswax.

Rice. 3. Essential oils.

What have we learned?

Esters, depending on their structure, are liquids or solids. The properties of the compounds are determined by the presence of the carboxyl group -COOH. Esters undergo combustion, substitution, addition, and reduction reactions. Under the influence of water they decompose into carboxylic acids and alcohols (reverse esterification reaction).

Test on the topic

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To practice, take the VPR test 2017 chemistry grade 11 Option 2

Instructions for performing the work

The test includes 15 tasks. 1 hour 30 minutes (90 minutes) is allotted to complete the chemistry work.

Formulate your answers in the text of the work according to the instructions for the assignments. If you write down an incorrect answer, cross it out and write a new one next to it.

When performing work, you are allowed to use the following additional materials:

– Periodic table chemical elements D.I. Mendeleev;

– table of solubility of salts, acids and bases in water;

– electrochemical series of metal voltages;

– non-programmable calculator.

When completing assignments, you can use a draft. Entries in draft will not be reviewed or graded.

We advise you to complete the tasks in the order in which they are given. To save time, skip a task that you cannot complete immediately and move on to the next one. If you have time left after completing all the work, you can return to the missed tasks.

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Name

№1 One of scientific methods knowledge of substances and chemical phenomena is modeling. Thus, molecular models are used to establish the relationship between the structure and properties of substances. In Fig. Figures 1–3 show models of molecules of three substances.

Which of the substances, the molecular models of which are shown in the figures, belong to:

1) simple substances;

2) complex inorganic substances.

Write down the drawing number and chemical formula of this substance.
Substance
Simple
Figure number

Chemical formula

Substance

Complex inorganic substance

Figure number

Chemical formula

№2 The picture shows the model electronic structure an atom of some chemical element.

The assignment of this part is checked separately by experts. Answers may vary, for example Bases: Ba(OH)2

Fill in the name of the missing group for CaO

The assignment of this part is checked separately by experts. The answers may be different, for example Salts: Na3PO4

In your answer, fill in the missing group name for HNO3

To complete tasks 6–8, use the information contained in this text.

The chemical element sodium is the sixth most abundant element on Earth among all chemical elements. Natural sodium compounds are rock salt, cryolite, borax, etc. Sodium is also present in almost all organs, biological fluids and tissues of the human body and performs special role in intracellular and intercellular metabolic processes.

The simple substance sodium is one of the most chemically active metals. It is capable of reacting with water at room temperature. The resulting substance is called sodium hydroxide (NaOH) or sodium hydroxide. It received this name because it “corrodes” fabrics, leather, and paper. In air, sodium hydroxide absorbs carbon dioxide (CO2) and turns into a salt - sodium carbonate (Na2CO3). This salt is widely used in various areas industry. For example, in the food industry, sodium carbonates are registered as food additives E500, used as an acidity regulator, leavening agent, preventing clumping and caking of food products.

№6

1) Write an equation for the reaction of sodium with water.

2) In the form of what particles (atoms or ions) chemical element Is sodium found in extracellular fluids in the human body? Write the name and chemical formula of these particles.

№7

1) Write a molecular equation for the reaction between sodium hydroxide and carbon dioxide.

2) What is the common name for sodium hydroxide? What properties of sodium hydroxide give rise to this name?

Write down your answer, and after testing, look at the answers with a detailed solution.

№8

1) Make up an abbreviation ionic equation reaction between sodium carbonate solution and excess nitric acid (HNO3).
2) What external signs of this reaction indicate that this reaction has proceeded to completion?

Write down your answer, and after testing, look at the answers with a detailed solution.

№9 A scheme of the redox reaction is given.

P + HNO3 + H2O → H3PO4 + NO

1. Make an electronic balance for this reaction.

2. Identify the oxidizing agent and reducing agent.

3. Arrange the coefficients in the reaction equation.
Write down your answer, and after testing, look at the answers with a detailed solution.

№10 The transformation scheme is given:

CO2 → Na2CO3 → CaCO3 → CaCl2

Write molecular reaction equations that can be used to carry out these transformations.

Write down your answer, and after testing, look at the answers with a detailed solution.

№11 Match the formula organic matter and its name: for each position indicated by a letter, select the corresponding position indicated by a number.

FORMULA OF THE SUBSTANCE

NAME

1) formic acid

2) glycerin

3) ethanol

Write down the selected numbers under the corresponding letters.