Liquid bromine, phenol solution is what has the best picture to talk about in detail

A, liquid bromine

Deep brownish-red heavy liquid, easy to volatilize, can freeze into a solid when the temperature is low. Very strong toxicity and corrosiveness. At room temperature, can be volatile with a strong irritant smoke, irritate the eyes and respiratory mucosa, make people tear and cough, can burn the skin, resulting in severe pain, not easy to cure. The nature of bromine is very active, is a strong oxidizing agent, meet arsenic, antimony release sparks and chemically. Affinity with hydrogen is very strong, similar to chlorine but slightly weaker, mixed with organic matter, can cause combustion. Soluble in alcohol, ether, potassium bromide solution, alkali and carbon disulfide, soluble in water. Reducing substances such as ethylene can discolor bromine water, a common reaction in high school chemistry.

Liquid bromine, reddish brown

Two, phenol

Phenol (Phenol, C6H5OH), ? is a colorless needle-like crystal with a peculiar odor, toxic, is an important raw material for the production of certain resins, fungicides, antiseptics, and drugs (such as aspirin). It can also be used to disinfect surgical instruments and excreta treatment, skin sterilization, anti-itching and otitis media. Melting point 43 ℃, slightly soluble in water at room temperature, soluble in organic solvents; when the temperature is higher than 65 ℃, can be mutually soluble with water in any proportion. Phenol is corrosive, after contact with local protein denaturation, its solution on the skin can be washed with alcohol. A small portion of phenol exposed to air is oxidized by oxygen to quinone and pink. When trivalent iron ions turn purple, usually use this method to test phenol.

Phenol is a German chemist Runge (Runge F) in 1834 in the coal tar found, so it is also known as carbolic acid (Carbolic acid). Phenol's first notoriety should be attributed to the famous British doctor Rist. Rist found that the cause of death of patients after surgery is mostly pus infection of the wound. By accident, a dilute solution of phenol was used to spray surgical instruments and the surgeon's hands, resulting in a significant reduction in patient infections. This discovery made phenol a powerful surgical antiseptic. Rist is known as the "Father of Surgical Sterilization".

Phenol solution

Molecular structure

The phenol molecule consists of a hydroxyl group attached directly to the benzene ring.

Due to the stability of the benzene ring, such a structure is almost never converted to a ketone structure[5]?

The phenol *** vibrational structure is shown above right. The oxygen atom of the phenol hydroxyl group is sp2 hybridized, providing a lone pair of electrons to form an off-domain bond with the six carbon atoms of the benzene ring***. The large π bond strengthens the acidity of the enol, and the electron-pushing effect of the hydroxyl group strengthens the polarity of the O-H bond, so that the hydrogen of the hydroxyl group in phenol can be ionized.

The phenol salt anion then has a ***vibrational structure as shown below right:

Molar refractive index: 28.13

Molar volume (m3/mol): 87.8

Isotropic specific volume (90.2 K): 222.2

Surface tension (dyne/cm): 40.9

Polarizability: 11.15[5]?

Physical Properties

Relative Vapor Density (air=1): 3.24

Refractive Index 1.5418

Saturated Vapor Pressure (kPa): 0.13 (40.1°C)

Heat of Combustion (kJ/mol): 3050.6

Critical Temperature (°C): 419.2

Logarithm of Distribution Coefficient of Octanol/Water:1.46

Upper Explosive Limit %(V/V):8.6

Initiation Temperature(℃):715

Lower Explosive Limit %(V/V):1.7

Solubility: miscible in Ether, Chloroform, Glycerol, Carbon Disulfide, Vaseline, volatile oil, strong alkali solution. Soluble in ethanol, glycerol, chloroform, ether and other organic solvents at room temperature, slightly soluble in water, mixed with about 8% water can be liquefied, 65 ℃ and above can be miscible with water, almost insoluble in petroleum ether. [1]?

Chemical properties

Can absorb moisture in the air and liquefy. Has a special odor, very dilute solution has a sweet taste. Extremely corrosive. Strong chemical reaction ability. React with aldehydes and ketones to generate phenolic resins, bisphenol A, and acetic anhydride; salicylic acid reaction to generate phenyl acetate, salicylic acid ester. Can also be halogenated, hydrogenated, oxidized, alkylated, carboxylated, esterified, etherified and other reactions. Phenol is solid at the usual temperature, and sodium can not be successfully reacted, if you use heating to melt phenol, and then add the method of sodium metal for the experiment, phenol is easy to be reduced, and the color of phenol changes when heated and affects the experimental results. Some people in the teaching of the following method of experiment, the operation is simple, and achieved satisfactory experimental results. Add 2-3 ml of anhydrous ether in a test tube, take a piece of sodium metal the size of a soybean grain, use filter paper to absorb the kerosene on the surface and put it into the ether, you can see that the sodium does not react with the ether. Then add a small amount of phenol to the test tube, shaking, then you can observe the sodium in the test tube to react quickly, producing a large amount of gas. The principle of this experiment is that phenol dissolves in ether, allowing the reaction of phenol with sodium to proceed smoothly.

Acid-base reactions

Phenol belongs to the phenolic substances, there is a weak acidity, and can react with bases:

PhOH + NaOH → PhONa + H2O

Phenol Ka = 1.28 × 10-10, the acidity of the carbonic acid between two levels of ionization, so phenol can not be reacted with weak bases such as NaHCO3:

PhOˉ +CO2+H2O→PhOH+HCO3ˉ

Phenomenon of this reaction: white turbidity appears in the solution after carbon dioxide is passed in.

Reason: Phenol is precipitated due to small solubility.

Chromogenic reaction

Phenol shows purple color when met with ferric chloride solution because phenol root ions form colorful complexes with Fe.

6PhOH+FeCl3→H3[Fe(OPh)6](purple)+3HCl

Substitution Reactions

Electrophilic Substitution

Phenol, due to the presence of the benzene ring in its structure, can undergo electrophilic substitution reactions on its ring similar to those of benzene, e.g., nitration, halogenation,etc.

Comparison of the corresponding reaction of benzene reveals that substitutions on the phenol ring are much easier than those of benzene. substitution is much easier than benzene. This is due to the electron-donating effect of the hydroxyl group, which increases the density of the benzene ring electron cloud.

It is worth noting that the electrophilic substitution of phenol always occurs in the neighboring and opposite positions of the hydroxyl group. This is the *** nature of electron-donating groups such as the hydroxyl group.

Substitution on Phenol Hydroxyl Groups

Hydrogen atoms on phenol hydroxyl groups can be replaced by carbon-containing groups to form ethers or esters.

Redox

Phenol turns

pink when left in air for a long time because of the formation of benzoquinone:

The oxidation product of phenol is usually p-benzoquinone. This reaction can also use Br2 as an oxidizing agent.

Condensation reaction

Condensation of phenol with formaldehyde catalyzed by an acid or base produces phenolic resins.