Ethanal or acetaldehyde is an important intermediate product for obtaining many basic organic products. Among them are acetic, acetic anhydride, ketene-diketene, ethyl acetate, crotonic aldehyde, n -butanol, 2-ethylhexanol, pentaerythrite, chloral, pyridines and many more. In obtaining acetic and its anhydride, most of the total production of acetaldehyde is consumed, while it is the one that increases the most.
Summary
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- 1 Story
- 2 Molecular model of ethanal
- 3 Physical properties
- 4 Obtaining
- 5 Applications
- 6 Toxicology
- 1 Chemical hazards
- 7 Health risks
- 1 First aid
- 8 Physical hazards
- 1 Exposure routes
- 2 Risk of inhalation
- 3 Short-term exposure effects
- 4 Effects of prolonged or repeated exposure
- 9 Source
- 10 External links
History
Ethanal was first synthesized in 1782 by Scheele by oxidation of ethanol with manganese dioxide (MnO 2 ). Its formula was first found out by Liebig in 1835 who gave it the name of acetaldehyde.
Ethanal molecular model
- Synonyms: Acetaldehyde, ethanal
- Formula: C 2H 4 O / CH 3 CHO
- Molecular mass: 44.1
- Melting point: -123.5ºC
- Boiling point: 20.1ºC
- Comment: Colorless liquid with pungent fruit odor.
Physical properties
It is interesting, acetaldehyde is important to say it has a boiling point of 21 degrees Celsius, just distill it you see as it boils. Another thing is that it smells medium well.
- It is a colorless liquid.
- It is easily oxidized to acetic acid and is very important in organic synthesis.
- Boiling point: 20.2 ° C
- Melting point: -123 ° C
- Relative density (water = 1): 0.78
- Solubility in water: miscible
- Vapor pressure, kPa at 20 ° C: 101
- Relative vapor density (air = 1): 1.5
- Flash point: -38 ºC cc
- Auto-ignition temperature: 185 ° C
- Explosive limits, vol% in air: 4-60
- Octanol / water partition coefficient as log Pow: 0.63.
The most common way to obtain acetaldehyde is the Wacker process, in which ethylene and oxygen are bubbled in an acidified solution of PdCl2-CuCl2:
Acetaldehyde is a colorless, volatile liquid with a pungent fruit odor. It is important as an intermediate in the manufacture of numerous chemicals, medicines, and plastics, including ethanoic acid (acetic acid), butanol (butyl alcohol), trichloroethanal (chloral), and pyridine. It is miscible with water and with most common organic solvents.
Obtaining
- In the laboratory it can be obtained by oxidationof ethanol. It is formed, for example, with potassium dichromate, a reaction that is used to detect ethanol in expired air.
- One of the industrial methods for obtaining ethanal is the hydration of acetylene, although it is currently being replaced by the oxidation of ethylene.
Applications
In the presence of acids, acetaldehyde forms oligomers. Trimer (paraldehyde) has been used as a sleeping pill. The tetramer is used as a solid fuel. Ethanal is a starting product in the synthesis of plastics, paints, lacquers, in the rubber, paper and leather tanning industries. It is even used as a preservative in the food industry.
Once it has been concluded that a wine is suitable for aging in barrels after following the path of the grape, if it comes from an old or young vineyard, the conduction system (low or trellis size) of the Tillage and of the phytosanitary products used for pests, if any, we must have defined the product that we want to obtain for its subsequent sale in the market.
To carry out an evolutionary knowledge of the prolongation of the life of the wine that is going to age and that will later reach the consumer, three basic points must be addressed:
– Ethanal or acetaldehyde. – Coloring matter. – Polymerization.
Ethanal.- Ethanal or acetaldehyde is a compound that is generated in fermentation and that creates a certain incidence in:
– Volatile acidity. – The stabilization of the coloring matter. – The tasting.
Sulfurous is an ethanal inhibitor additive since it combines stably with it. When sulphurous levels drop, the “event” or ethanalized odor appears. The levels below 60 mg / la from the fermentation seem to be adequate for a harmonious aging.
The ethanal of wines is the active element in the polymerization of polyphenolic matter; However, it is not clear that this factor is adequate for the balanced aging of wines.
Ethanal is a bond of polymerization. It is an essential component in color fixing, but in excess it causes color insolubilization.
Toxicology
The oxidation of ethanol to ethanal in the metabolism of the human body is considered as the main factor for the appearance of hangovers after the consumption of alcoholic beverages. It is manufactured by oxidation of ethene (ethylene) and ethanol (ethyl alcohol), or by the combination of water and ethin (acetylene). Ethanol has a melting point of -123.5 ° C, a boiling point of 20.8 ° C, and a density of 0.778 g / ml at 20 ° C.
Chemical hazards
The substance can form explosive peroxides in contact with air. The substance can polymerize under the influence of alkaline acids and hydroxides and under the presence of metallic traces ( iron ), with danger of fire or explosion. The substance is a strong reducing agent and reacts violently with oxidants, strong acids, halogens and amines, creating a fire and explosion hazard.
The substance is harmful to aquatic organisms. Ethanal or acetaldehyde (H3CC (= O) H) is a colorless, volatile liquid with a characteristic slightly fruity odor. Technically, ethanal is obtained by hydrating acetylene in the presence of mercury (II) salts:
H 2 O + H 3 C = CH 2 -> H 3 CC (= O) H)
Health risks
Extremely flammable. Irritant to the eyes and respiratory tract. Possible carcinogenic effects.
First aid
Inhalation: Remove person to fresh air. In case of suffocation, proceed to artificial respiration.
Skin contact: Wash with plenty of water. Remove contaminated Liberation Serif clothing.
Eyes: Wash with plenty of water (minimum for 15 minutes), keeping the eyelids open. Seek medical attention.
Ingestion: Drink plenty of water. Cause vomiting. Immediately seek medical attention.
Physical hazards
Steam is denser than air and can spread low to the ground; possible ignition at distant point. Exposure limits: TLV: 25 ppm as STEL; (ceiling value) A3 (ACGIH 2003). MAK: 50 ppm, 91 mg / m; Peak limitation category: I (1); Carcinogenic class: 3B; Risk class for pregnancy: D (DFG 2003 ).
Exposure routes
The substance can be absorbed by inhalation and by ingestion.
Inhalation risk
By evaporating this substance at 20 ° C a harmful concentration in the air can be reached very quickly.
Short-term exposure effects
The substance slightly irritates the eyes, the skin and the respiratory tract. The substance can affect the central nervous system.
Effects of prolonged or repeated exposure
Prolonged or repeated contact with the skin can cause dermatitis. The substance can affect the respiratory tract, leading to tissue disorders. This substance is posibly carcinogen to humans.
