2,2-Dimethyl-1,3-dioxane-4,6-dione Property

Melting point:

92-96 °C(lit.)

Boiling point:

182.71°C (rough estimate)

Density 

1.1311 (rough estimate)

vapor pressure 

0.044-133Pa at 25℃

refractive index 

1.4434 (estimate)

storage temp. 

2-8°C

solubility 

dioxane: soluble5%, clear to very slightly hazy, colorless to faintly yellow

pka

5.1(at 25℃)

form 

Crystals or Powder

color 

Brownish-white to beige-brown

Water Solubility 

2.5 g/100 mL (20 ºC)

Merck 

14,5817

BRN 

117310

InChIKey

GXHFUVWIGNLZSC-UHFFFAOYSA-N

LogP

-1.58-4.786 at 25℃

CAS DataBase Reference

2033-24-1(CAS DataBase Reference)

NIST Chemistry Reference

1,3-Dioxane-4,6-dione, 2,2-dimethyl-(2033-24-1)

EPA Substance Registry System

1,3-Dioxane-4,6-dione, 2,2-dimethyl- (2033-24-1)

Safety

Hazard Codes 

Xi,T

Risk Statements 

36/37/38-45

Safety Statements 

37/39-24/25-53-45-36-26

WGK Germany 

3

RTECS 

JH0800000

F 

10-21

TSCA 

Yes

HazardClass 

IRRITANT

HS Code 

29322090

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H315Causes skin irritation

H319Causes serious eye irritation

H335May cause respiratory irritation

Precautionary statements

P261Avoid breathing dust/fume/gas/mist/vapours/spray.

P304+P340IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P405Store locked up.

2,2-Dimethyl-1,3-dioxane-4,6-dione Chemical Properties,Usage,Production

Description

Meldrum's acid, also known as 2,2-dimethyl-1,3-dioxane-4,6-dione, is an organic compound with the formula C6H8O4. The compound was first made in 1908 by Andrew Norman Meldrum by a condensation reaction of malonic acid with acetone in acetic anhydride and sulfuric acid. Meldrum misidentified the structure as a β-lactone of β-hydroxyisopropylmalonic acid. Yet Meldrum's acid has a high acidity with a pKa of 4.97, because like ascorbic acid, deprotonation at the methylene next to the carbonyls produces a stable enolate. Because of this property Meldrum's acid like malonic acid is a reactant in Knoevenagel condensations.

Chemical Properties

The compound appears as white to beige crystals. It has a melting point of 94-95℃ (decomposition), is insoluble in water, and is soluble in ethanol and acetone.

Application

2,2-Dimethyl-1,3-dioxane-4,6-dione was used in the synthesis of:
    macrocyclic β-keto lactone
    4-pyridyl-substituted heterocycles
    2-substituted indoles
    isofraxidin.

Uses

Meldrum's acid serves as an intermediate in a variety of organic synthesis reactions. It is commonly used as an alternative to acyclic malonic esters and generally acts as a C3O2 synthon in organic synthesis.

Uses

An antimicrobial agent

Preparation

2,2-Dimethyl-1,3-dioxane-4,6-dione is usually prepared by condensation of malonic acid with acetone in acetic anhydride in the presence of sulfuric acid. Excellent yield of the product was achieved when acetic anhydride was added in a slow, controlled manner to a mixture of acetone, malonic acid and an acid catalyst.

Synthesis Reference(s)

Journal of the American Chemical Society, 70, p. 3426, 1948 DOI: 10.1021/ja01190a060

General Description

2,2-Dimethyl-1,3-dioxane-4,6-dione (Meldrum′s acid) is widely used in organic synthesis, especially for multiple C-C bond formations due to its adequate acidity (pK_a 4.83) and steric rigidity. Knoevenagel condensation reaction between aldehydes and Meldrum′s acid are accelerated in ionic liquids.

Flammability and Explosibility

Non flammable

Purification Methods

Crystallise the dione from Me2CO/H2O. It is a synthon for the C3 malonic acid moiety. [Arnette et al. J Am Chem Soc 106 6759 1984, Bihlmayer et al. Monatsh Chem 98 564 1967, Review: McNab Chem Soc, Rev 7 345 1978, Chan & Huang Synthesis 452 1982, Beilstein 19/5 V 8.]