Diethyl malonate

Structural formula
General
Surname	Diethyl malonate
other names	Diethyl malonate; Malonic ester;
Molecular formula	C 7 H 12 O 4
Brief description	colorless liquid with an aromatic odor
External identifiers / databases
EC number	203-305-9
ECHA InfoCard	100.003.006
PubChem	7761
ChemSpider	13863636
Wikidata	Q27887610
properties
Molar mass	160.17 g · mol -1
Physical state	liquid
density	1.05 g cm −3
Melting point	−50 ° C
boiling point	199 ° C; 92 ° C (18 hPa);
Vapor pressure	0.35 h Pa (20 ° C); 1.29 hPa (40 ° C); 2.37 hPa (50 ° C);
solubility	Easily soluble in almost all organic solvents; soluble in water (20.8 g l −1 );
Refractive index	1.414 (20 ° C)
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 319
	P: 305 + 351 + 338
Toxicological data	> 16,000 mg kg −1 ( LD 50 , rabbit , transdermal ) ; 15,000 mg kg −1 ( LD 50 , rat , oral ) ;
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Diethyl malonate is a colorless, pleasant-smelling liquid that is one of the esters .

Extraction and presentation

Diethyl malonate cannot be obtained from the free acid by esterification with ethanol because malonic acid breaks down at elevated temperatures to form acetic acid and CO ₂ ( decarboxylation ). The sodium salt of cyanoacetic acid has to be reacted with ethanol and concentrated mineral acids to produce it.

properties

Physical Properties

Diethyl malonate is a colorless liquid that boils at 199 ° C under normal pressure . According to Antoine, the vapor pressure function results from log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 5.90564, B = 2864.822 and C = 13.407 im Temperature range from 313 to 472 K. Miscibility with water is limited. As the temperature rises, the solubility of diethyl malonate in water falls to about 50 ° C. and then increases again or the solubility of water in diethyl malonate increases.

Solubilities between diethyl malonate and water
temperature	° C	0	9.1	20.0	31.0	39.6	49.9	60.2	70.5	81.0	90.6
Diethyl malonate in water	in%	3.09	2.80	2.26	2.10	2.09	2.05	2.12	2.18	2.33	2.47
Water in diethyl malonate	in%	1.09	1.28	1.60	1.92	2.16	2.62	2.91	3.63	4.02	4.30

Chemical properties

The methylene protons of diethyl malonate are slightly acidic; therefore it can with strong bases such as B. sodium ethanolate are deprotonated. This deprotonated form is a carbanion and can be converted with alkyl halides to alkyl-substituted malonic acid diethyl esters ( malonic ester synthesis ). Other possible reactions of this carbanion:

Reaction with carbonyl derivatives ( aldehydes or ketones ) leads to aldol products
Reaction with carboxylic acid derivatives leads to acylation

Safety-related parameters

Diethyl malonate forms flammable vapor-air mixtures at elevated temperatures. The compound has a flash point of 85 ° C. The explosion range is between 0.8 vol.% As the lower explosion limit (LEL) and 12.8 vol.% As the upper explosion limit (UEL). The ignition temperature is 435 ° C. The substance therefore falls into temperature class T2.

use

If alkyl-substituted malonic acid diethyl esters are hydrolyzed to give the corresponding alkylated malonic acids and then heated, they decarboxylate like malonic acid itself; substituted acetic acid derivatives are formed with the elimination of carbon dioxide (see malonic ester synthesis ). Alkyl-substituted malonic acid diethyl esters can also be reacted with urea to form barbituric acid derivatives . The reaction is related to the Knoevenagel reaction .

Individual evidence

↑ ^a ^b ^c data sheet diethyl malonate (PDF file; 73 kB) from SysKem Chemiehandel GmbH, accessed on January 23, 2016.
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on diethyl malonate in the GESTIS substance database of the IFA , accessed on November 8, 2017(JavaScript required) .
↑ ^a ^b ^c ^d D'Ans-Lax, paperback for chemists and physicists, volume 2, third edition 1964.
↑ ^a ^b ^c Data sheet Diethyl malonate from Sigma-Aldrich , accessed on November 4, 2016 ( PDF ).
↑ Entry on diethyl malonate. In: Römpp Online . Georg Thieme Verlag, accessed on January 2, 2015.
^ Stull, DR: Vapor Pressure of Pure Substances. Organic and Inorganic Compounds in Ind. Eng. Chem. 39 (1947) 517-540, doi : 10.1021 / ie50448a022
^ ^A ^b R. M. Stephenson: Mutual Solubilities: Water-Ketones, Water-Ethers, and Water-Gasoline-Alcohols in J. Chem. Eng. Data 37 (1992) 80-95, doi : 10.1021 / je00005a024 .

[syskem-1] ta sheet diethyl malonate (PDF file; 73 kB) from SysKem Chemiehandel GmbH, accessed on January 23, 2016.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on diethyl malonate in the GESTIS substance database of the IFA , accessed on November 8, 2017(JavaScript required) .

[Lax-3] D'Ans-Lax, paperback for chemists and physicists, volume 2, third edition 1964.

[Sigma-4] Data sheet Diethyl malonate from Sigma-Aldrich , accessed on November 4, 2016 ( PDF ).

[Römpp-5] Entry on diethyl malonate. In: Römpp Online . Georg Thieme Verlag, accessed on January 2, 2015.

[Stull-6] Stull, DR: Vapor Pressure of Pure Substances. Organic and Inorganic Compounds in Ind. Eng. Chem. 39 (1947) 517-540, doi : 10.1021 / ie50448a022

[Stephenson-7] A ^b R. M. Stephenson: Mutual Solubilities: Water-Ketones, Water-Ethers, and Water-Gasoline-Alcohols in J. Chem. Eng. Data 37 (1992) 80-95, doi : 10.1021 / je00005a024 .