Synonyms:

Group of substances:

Physical appearance:

Empirical formula (Hill's system for organic substances):

Structural formula as text:

Molar/atomic mass: 44.05

Melting point (°C):

Boiling point (°C):

Solubility (g/100 g of solvent):

Density:

Synthesis 1:

50 ml paraldehyde, 0,5 ml concentrated sulfuric acid (acting as depolymerization agent) and several pieces of porous porcelain (note 1) is placed into round-bottomed flask, equiped with reflux column (height 50-60 cm), a thermometre, attached to it, and a good working downward condenser with a curved allonge, placed into a receiving flask (100 ml), cooled with ice. The opening of the receiving flask is covered with a piece of cotton to decrease wastes from evaporation of acetaldehyde. Then a flask (with reagents) is heated with great caution on the water bath, keeping the temperature between 50-60 C. The temperature of outgoing vapors mustn't be higher than 30-32 C.

For the reason that acetaldehyde forms a constant-boiling (azeotrope) mixture with paraldehyde, which have boiling point at 42 C (53,4 mol.% acetaldehyde and 46,6 mol.% paraldehyde). For separation of acetaldehyde from this mixture the fractionation process must be as effecient as possible, a distillation should be carried out very slowly. It is found that most of acetaldehyde is distilled at 21-25 C.

The distillation is ended when 8-10 ml of liquid remains in the flask. During the distillation until dryness the explosion takes place!

Acetaldehyde is obtained with a very good yield by this method. The stuff is quite pure and in some case can be used without further purification. For example, for qualitative tests on aldehydes.

Pure acetaldehyde is obtained by the second distillation, using the same setting, but a smaller flask (100 ml). The flask is cooled with ice in advance. Cooled acetaldehyde is poured into the flask. The flask is connected to the setting quickly. The flask is heated with caution on the water bath, the temperature is regulated in order to make a slow distillation of aldehyde at the constant temperature of the bath.

Data from thermometre, placed in the reflux column, depends on air temperature in the laboratory, if it is higher then 21 C.

Pure acetaldehyde boils at 21 C. The yield is 40 g.

Note: Sulfuric acid can be changed with 1-2 gramms of sulfamic acid (NH2SO3H) or p-toluenesulfonic acid (p-CH3-C6H4-SO3H).

[Translated by Ivan Novikov]

Reactions of synthesis:

1. [Ref.1]
   C₂H₅OH + MnO₂ + H₂SO₄ → CH₃CHO + MnSO₄ + 2H₂O
   

Reactions:

1. Yeild 35%. [Ref.1]
   CH₃CHO + SF₄ → CH₃CHF₂ + SOF₂
   
2. Yeild 68%. [Ref.1]
   CH₃CHO + NH₃ + H₂ → CH₃CH₂NH₂ + H₂O
   

Refractive index (n_D):

Dissociation:

Permittivity (dielectric constant):

Dipole moment (D):

Viscosity (mPa·s):

Surface tension (mN/m):

Standard molar enthalpy (heat) of formation Δ_fH⁰ (298.15 K, kJ/mol):

Standard molar Gibbs energy of formation Δ_fG⁰ (298.15 K, kJ/mol):

Standard molar entropy S⁰ (298.15 K, J/(mol·K)):

Molar heat capacity at constant pressure C_p (298.15 K, J/(mol·K)):

Enthalpy (heat) of vaporization Δ_vapH (kJ/mol):

Autoignition temperature (°C):

Heat of combustion (kJ/mol):

Standard molar enthalpy (heat) of formation Δ_fH⁰ (298.15 K, kJ/mol):

Standard molar Gibbs energy of formation Δ_fG⁰ (298.15 K, kJ/mol):

Standard molar entropy S⁰ (298.15 K, J/(mol·K)):

Molar heat capacity at constant pressure C_p (298.15 K, J/(mol·K)):

LD₅₀ (mg/kg):

Critical temperature (°C):

Critical pressure (MPa):

References:

1. CRC Handbook of Chemistry and Physics. - 90ed. - CRC Press, 2010. - pp. 5-22
   
2. Dean J.A. Lange's handbook of chemistry. - 1999. - pp. 1.76
   
3. Lewis R.J. Sax's Dangerous Properties of Industrial Materials. - 11ed. - Wiley-interscience, 2004. - pp. 5-6
   
4. Milne G.W.A. Gardner's Commercially Important Chemicals. - Wiley-Interscience, 2005. - pp. 4
   
5. Seidell A. Solubilities of organic compounds. - 3ed., vol.2. - New York: D. Van Nostrand Company, 1941. - pp. 100
   
6. Волков А.И., Жарский И.М. Большой химический справочник. - Минск: Современная школа, 2005. - pp. 248 [Russian]
   
7. Некрасов Б.В. Основы общей химии. - Т.1. - М.: Химия, 1973. - pp. 560 [Russian]
   
8. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 187 [Russian]
   
9. Справочник химика. - Т. 2. - Л.-М.: Химия, 1964. - pp. 1030-1031 [Russian]
   
10. Справочник химика. Дополнительный том: Номенклатура органических соединений, техника безопасности, сводный предметный указатель. - Л.: Химия, 1968. - pp. 473 [Russian]
    
11. Тюкавкина Н.А., Бауков Ю.И. Биоорганическая химия. - М.: Медицина, 1985. - pp. 189 [Russian]
    
12. Химическая энциклопедия. - Т. 1. - М.: Советская энциклопедия, 1988. - pp. 224 [Russian]
    
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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru