Malonic acid

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Malonic acid
Names
IUPAC name
Propanedioic acid
Preferred IUPAC name
Propanedioic acid
Other names
Carboxyacetic acid
Dicarboxymethane
Methanedicarboxylic acid
Properties
C3H4O4
CH2(COOH)2
Molar mass 104.061 g/mol
Appearance White crystalline solid
Odor Odorless
Density 1.619 g/cm3
Melting point 135–140 °C (275–284 °F; 408–413 K) (decomposes)
Boiling point Decomposition
76.3 g/100 ml (25 °C)
Solubility Reacts with bases, amines
Soluble in alcohols
Vapor pressure ~0 mmHg
Acidity (pKa) pKa1 = 2.83
pKa2 = 5.69
Thermochemistry
Hazards
Safety data sheet Sigma-Aldrich
Flash point 157 °C (314.6 °F; 430 K)
Lethal dose or concentration (LD, LC):
3250 mg/kg (rat, oral)
Related compounds
Related compounds
Oxalic acid
Succinic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Malonic acid or propanedioic acid is a dicarboxylic acid with structure CH2(COOH)2.

Properties

Chemical

If malonic acid is mixed with phosphorus pentoxide and heated, carbon suboxide is formed.[1]

Reduction of malonic acid yields 1,3-propanediol, the other isomer of propylene glycol.

Malonic acid may also condensed be with acetone to form Meldrum's acid, a versatile intermediate in further transformations.

Malonic acid is a key component in the Briggs–Rauscher reaction or Belousov–Zhabotinsky reaction, the classic examples of oscillating chemical reactions.

Physical

Malonic acid is a crystalline solid, soluble in water.

Availability

Malonic acid can be bought from chemical suppliers.

Preparation

The most common route to malonic acid involves neutralizing chloroacetic acid with sodium carbonate, which yields sodium chloroacetate. Addition of sodium cyanide will form sodium cyanoacetate, via a nucleophilic substitution. The nitrile group is then hydrolyzed with aq. sodium hydroxide to sodium malonate, and acidification affords malonic acid.

Cl-CH2COOH + Na2CO3 → Cl-CH2COONa + H2O + CO2
Cl-CH2COONa + NaCN → CN-CH2COONa + NaCl
CN-CH2COONa + 2 NaOH → CH2(COONa)2
CH2(COONa)2 + 2 H+ → CH2(COOH)2 + 2 Na+

Projects

  • Make malonate esters and salts
  • Preparation of barbituric acid
  • Make carbon suboxide
  • Preparation of 1,3-propanediol
  • Demonstration of oscillating chemical reactions

Handling

Safety

Malonic acid is irritant, and has low toxicity.

Storage

In closed plastic or glass bottles.

Disposal

No special disposal is required. Can be neutralized with a base and poured down the drain.

References

  1. https://zenodo.org/record/1426170#.YZFI7VVBzIU

Relevant Sciencemadness threads