Dimethylformamide

This article deals with an amide of formic acid. For dimethyl fumarate, which is also abbreviated as DMF, see dimethyl fumarate .

Structural formula
General
Surname	Dimethylformamide
other names	N , N -dimethyl methanamide N , N -dimethylformamide Formic acid dimethylamide DMF
Molecular formula	C 3 H 7 NO
Brief description	colorless to yellowish liquid with a slightly amine-like odor
External identifiers / databases
CAS number 68-12-2 EC number 200-679-5 ECHA InfoCard 100,000,617 PubChem 6228 ChemSpider 5993 DrugBank DB01844 Wikidata Q409298
properties
Molar mass	73.10 g mol −1
Physical state	liquid
density	0.95 g cm −3 (20 ° C)
Melting point	−61 ° C
boiling point	153 ° C
Vapor pressure	3.77 h Pa (20 ° C) 6.75 hPa (30 ° C) 12.8 hPa (40 ° C) 22.9 hPa (50 ° C)
solubility	miscible with water and many organic solvents
Dipole moment	3.82 (8) D (1.3 x 10 -29  C  ·  m )
Refractive index	1.4305 (20 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 226-312-332-319-360D P: 201-210-302 + 352-304 + 340-305 + 351 + 338-308 + 313
Authorization procedure under REACH	of particular concern : toxic for reproduction ( CMR )
MAK	DFG : 5 ml m −3 or 15 mg m −3 Switzerland: 5 ml m −3 or 15 mg m −3
Thermodynamic properties
ΔH f 0	−239.3 kJ / mol
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

Dimethylformamide ( DMF ), more precisely N , N -dimethylformamide , is an amide of formic acid . DMF is used as a polar, aprotic, organic solvent .

The use as a solvent for polyacrylonitrile , which made it possible to use it as synthetic fiber (Orlon, Dralon et al.), Was discovered in 1941 by Herbert Rein at IG Farben and in 1944 independently at DuPont in the USA.

Manufacturing

The large-scale production of DMF takes place in two different ways, according to a one-step and a two-step process. In the one-step synthesis , dimethylamine is converted directly to DMF with carbon monoxide at elevated temperature and pressure. The reaction is carried out in the liquid phase with the help of a catalyst ( sodium ethanolate ):

${\displaystyle \mathrm {(CH_{3})_{2}NH+CO\longrightarrow (CH_{3})_{2}N{-}CHO} }$

In the two-stage synthesis, the reaction of dimethylamine with methyl formate is carried out, methanol is formed as a by-product:

${\displaystyle \mathrm {(CH_{3})_{2}NH+HCOOCH_{3}\longrightarrow (CH_{3})_{2}N{-}CHO+CH_{3}OH} }$

Both syntheses proceed with high yields without the formation of significant by-products. The product is worked up in both cases by multi-stage distillation.

properties

Physical Properties

DMF is a colorless to yellowish, non-volatile liquid that mixes with water and many organic solvents. The compound boils at 153 ° 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 = 3.93068, B = 1337.716 and C = −82.648 in the temperature range from 303 K to 363 K. Important thermodynamic parameters are given in the following table:

Compilation of the most important thermodynamic properties

property	Type	Value [unit]	Remarks
Standard enthalpy of formation	Δ f H 0 liquid	−239.4 kJ mol −1	as a liquid
Enthalpy of combustion	Δ c H 0 liquid	−1941.6 kJ mol −1	as a liquid
Heat capacity	c p	148.16 J mol −1 K −1 (25 ° C) 2.03 J g −1 K −1 (25 ° C)	as a liquid
Critical temperature	T c	649.6 K
Critical density	ρ c	3.82 mol·l −1
Enthalpy of evaporation	Δ V H 0 Δ V H	46.7 kJ mol −1 39.409 kJ mol −1	at boiling point
Enthalpy of fusion	Δ F H	8.95 kJ mol −1

The temperature dependence of the enthalpy of vaporization can be calculated according to the simplified Watson equation Δ _V H = A · (1 − T _r ) ⁿ (Δ _V H in kJ / mol, T _r = (T / T _c ) reduced temperature) with A = 59.3545 Describe kJ / mol, n = 0.381 and T _c = 647.0 K in the temperature range between 213 K and 647 K.

The compound forms azeotropically boiling mixtures with n-heptane at 97 ° C. with a content of 5% by mass or with ethylbenzene at 134 ° C. with a content of 15% by mass. No azeotropes are formed with water , methanol , ethanol , benzene , toluene , and acetonitrile .

Chemical properties

The amide decomposes to dimethylamine and carbon monoxide when exposed to light and heat . Solutions in water are resistant to hydrolysis. Additions of acids or bases catalyze the decomposition into formic acid and dimethylamine. As a solvent, the compound is not inert to a number of substances. Violent reactions occur with substances such as sodium hydride , sodium tetrahydroborate , lithium azide , sodium , thionyl chloride and triethylaluminum . It also reacts with halogenated hydrocarbons, such as carbon tetrachloride .

Safety-related parameters

Dimethylformamide forms flammable vapor-air mixtures. The compound has a flash point of 58 ° C. The explosion range is between 2.2% by volume (70 g / m³) as the lower explosion limit (LEL) and 16% by volume (500 g / m³) as the upper explosion limit (UEL). The upper explosion point here is 51 ° C. The maximum explosion pressure is 7.2 bar. The limit gap width was determined to be 1.02 mm. This results in an assignment to explosion group IIA. The ignition temperature is 440 ° C. The substance therefore falls into temperature class T2.

use

• DMF serves as a solvent for a large number of solid, liquid or gaseous substances, for polymers such as polyacrylonitrile , PVC , polyamides , polyurethanes , epoxy resins , and for cellulose and its derivatives .
• DMF serves as a catalyst in the production of acid chlorides from carboxylic acids and oxalyl chloride.
• Because DMF is polar aprotic , it is often used as a solvent in the laboratory for reactions with polar transition states. In the case of nucleophilic substitutions , compared to z. B. methanol drastic speed increases are recorded.
• In chemical engineering, DMF is used as an extractant to separate benzene , ethyne and 1,3-butadiene .
• DMF is an additive to kerosene , it serves as a catalyst for its combustion
• DMF is an intermediate in the synthesis of acetals , aldehydes , carboxylic acid esters and nitriles
• The Vilsmeier-Haack reagent , which is used for the formylation of aromatics and the chlorination of carboxylic acids , can be produced from DMF and phosphorus oxychloride .
• DMF is used as a reagent for the synthesis of aldehydes using Bouveault aldehyde synthesis .
• DMF-d ₇ is used as a solvent in NMR spectroscopy .

Deuterated dimethylformamide (DMF- d ₇ )

safety instructions

Liver cell damage can occur after both acute and chronic exposure. Histologically, microvesicular fat deposits ( fatty liver ) and changes in the liver tissue are then shown without pronounced inflammation.

DMF is listed in Appendix 6 to number 30 of Annex XVII of the REACH Regulation (EC) No. 1907/2006 as category 2 toxic to reproduction.

Individual evidence

1. ↑ ^{a b c d e f g h i j k l m n o p q} Entry on N, N-dimethylformamide in the GESTIS substance database of the IFA , accessed on May 19, 2017(JavaScript required) .
2. ↑ ^{a b c d} Entry on dimethylformamide. In: Römpp Online . Georg Thieme Verlag, accessed on August 1, 2012.
3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dipole Moments, pp. 9-55.
4. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-198.
5. ↑ Entry on N, N-dimethylformamide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
6. ↑ Entry in the SVHC list of the European Chemicals Agency , accessed on July 16, 2014.
7. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 68-12-2 or dimethylformamide (DMF) ), accessed on September 26, 2019.
8. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-24.
9. ↑ Gopal, R .; Rizvi, SA: Vapor Pressures of Some Mono- and Di-Alkyl Substituted Aliphatic Amides at Different Temperatures in J. Indian Chem. Soc. 45 (1968) 13-16.
10. ↑ ^{a b} Vasil'eva, TF; Zhil'tsova, EN; Vvedenskii, AA: Enthalpies of combustion of NN-dimethylformamide and NN-dimethylacetamide in Russ. J. Phys. Chem. (Engl. Transl.) 46 (1972) 315.
11. ↑ Kolker, AM; Kulikov, MV; Krestov, Al.G .: Volumes and heat capacities of binary non-aqueous mixtures. Part 2. The systems acetonitrile-N, N-dimethylformamide and acetonitrile-hexamethylphosphoric triamide in Thermochim. Acta 211 (1992) 73-84.
12. ↑ ^{a b} Teja, AS; Anselme, MJ: The critical properties of thermally stable and unstable fluids. I. 1985 results in AIChE Symp. Ser., 1990, 86, 279, 115-121.
13. ^ Panneerselvam, K .; Antony, MP; Srinivasan, TG; Vasudeva Rao, PR: Enthalpies of vaporization of N, N-dialkyl monamides at 298.15 K in Thermochimica Acta 495 (2009) 1-4, doi: 10.1016 / j.tca.2009.05.007 .
14. ^ ^{A b} Carl L. Yaws, Marco A. Satyro: Thermophysical Properties of Chemicals and Hydrocarbons - Chapter 7: Enthalpy of Vaporation, Organic Compounds , 1st Edition Elsevier 2008, ISBN 978-0-8155-1596-8 , p. 316, doi: 10.1016 / B978-081551596-8.50012-2 .
15. ↑ Smirnova, NN; Tsvetkova, L. Ya .; Bykova, TA; Marcus, Yizhak: Thermodynamic properties of N, N-dimethylformamide and N, N-dimethylacetamide in J. Chem. Thermodyn. 39 (2007) 1508-1513, doi: 10.1016 / j.jct.2007.02.009 .
16. ^ IM Smallwood: Handbook of Organic Solvent Properties. Arnold, London 1996, ISBN 0-340-64578-4 , pp. 245-247.
17. ↑ Daniel L. Comins, Sajan P. Joseph: Encyclopedia of Reagents for Organic Synthesis ( en ). John Wiley & Sons, Ltd, January 1, 2001, ISBN 978-0-470-84289-8 , doi : 10.1002 / 047084289x.rd335 .
18. ↑ PG Urben; MJ Pitt: Bretherick's Handbook of Reactive Chemical Hazards . 6th Edition, Vol. 1, Butterworth / Heinemann 1999, ISBN 0-7506-3605-X , pp. 131, 441.
19. ↑ ^{a b c d e f} E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.