Iodomethane

Structural formula
General
Surname	Iodomethane
other names	Methyl iodide; Monoiodomethane; Halon 10001;
Molecular formula	CH 3 I.
Brief description	colorless liquid with a pungent ethereal smell
External identifiers / databases
EC number	200-819-5
ECHA InfoCard	100,000,745
PubChem	6328
Wikidata	Q421729
properties
Molar mass	141.94 g mol −1
Physical state	liquid
density	2.28 g cm −3
Melting point	−66 ° C
boiling point	42 ° C
Vapor pressure	441 h Pa (20 ° C); 538 hPa (25 ° C); 630 hPa (30 ° C); 1318 hPa (50 ° C);
solubility	poor in water (8.66 g l −1 at 20 ° C)
Dipole moment	1.62 D (5.4 x 10 -30 C · m )
Refractive index	1.5304
safety instructions
H and P phrases	H: 301 + 331-312-315-319-335-351-410
	P: 273-302 + 352-304 + 340-305 + 351 + 338-308 + 310
MAK	repealed as a suspected carcinogenic effect; Switzerland: 0.3 ml m −3 or 2 mg m −3 ;
Toxicological data	76 mg kg −1 ( LD 50 , rat , oral )
Thermodynamic properties
ΔH f 0	−13.6 ± 0.5 kJ mol −1
	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

Iodomethane , outdated methyl iodide , is an organic halogen compound .

presentation

Iodomethane is formed in an exothermic reaction when iodine is added to a mixture of methanol and red phosphorus . The iodising reagent is phosphorus triiodide , which is formed in situ :

{\ displaystyle \ mathrm {2 \ P + \ 3 \ I_ {2} \ longrightarrow \ 2 \ PI_ {3}}}

{\ displaystyle \ mathrm {3 \ CH_ {3} OH \ + \ PI_ {3} \ longrightarrow \ 3 \ CH_ {3} I + H_ {3} PO_ {3}}}

Alternatively, iodomethane can be made by reacting dimethyl sulfate with potassium iodide in the presence of calcium carbonate :

{\ displaystyle \ mathrm {(CH_ {3} O) _ {2} SO_ {2} \ +2 \ KI \ longrightarrow \ K_ {2} SO_ {4} \ +2 \ CH_ {3} I}}

Methyl iodide / CH ₃ I can be purified from iodine by distillation and subsequent washing with Na ₂ S ₂ O ₃ .

Physical Properties

Bindings in detail

Iodomethane is a colorless, ethereal-smelling liquid at ambient temperature and normal pressure. The compound boils at 42.44 ° 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 = 4.1554, B = 1177.78 and C = −32.058 in the temperature range from 218 to 315.6 K or with A = 4.14897, B = 1223.831 and C = −20.179 in the temperature range from 315.6 to 521 K. The compound is hardly combustible. The explosion range is between 8.5% by volume (500 g / m ³ ) as the lower explosion limit (LEL) and 66% by volume (3870 g / m ³ ) as the upper explosion limit (UEL). The ignition temperature is 355 ° C. The substance therefore falls into temperature class T2.

Chemical properties

Iodomethane reacts with alkali and alkaline earth metals and is used for the methylation (introduction of a methyl group ) of organic substances. Ammonia and amines react with iodomethane to form methylammonium iodides. By repeating this reaction, quaternary ammonium ions can be generated (so-called exhaustive methylation), whereby the amine is released with a base after each step:

Quaternary ammonium ions can no longer be deprotonated by alkalis . Their salts are completely dissociated .

Toxic properties

Iodomethane has been shown to be carcinogenic in animal experiments .

Physiological effect

Like other methylation reagents (example: dimethyl sulfate ), iodomethane is carcinogenic and very toxic . The carcinogenic effect is causally linked to the methylating effect. Methyl iodide is a very good electrophile and therefore easily enters into nucleophilic substitution reactions with the body's own nucleophiles . This leads to a methylation of the DNA , which can then no longer be read correctly by the DNA polymerase during cell division .

Reactions

Monsanto trial

Iodomethane is part of the Monsanto catalytic cycle for the production of acetic acid .

use

Disodium methyl arsonate can be obtained by reacting with sodium arsenite in the presence of sodium hydroxide .

{\ displaystyle \ mathrm {Na_ {3} AsO_ {3} + CH_ {3} I \ longrightarrow CH_ {3} AsNa_ {2} O_ {3} + NaI}}

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Entry on iodomethane in the GESTIS substance database of the IFA , accessed on May 15, 2019(JavaScript required) .
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Permittivity (Dielectric Constant) of Gases, pp. 6-188.
↑ ^a ^b ^c Entry on iodomethane. In: Römpp Online . Georg Thieme Verlag, accessed on September 19, 2014.
↑ Entry on Iodomethane 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 .
↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 74-88-4 or iodomethane ), accessed on November 2, 2015.
↑ AS Carson, PG Laye, JB Pedley, Alison M. Welsby: The enthalpies of formation of iodomethane, diiodomethane, triiodomethane, and tetraiodomethane by rotating combustion calorimetry , in: The Journal of Chemical Thermodynamics , 1993 , 25 (2) , p. 261-269; doi : 10.1006 / jcht.1993.1025 .
^ ^A ^b CS King, WW Hartman: Methyl Iodide In: Organic Syntheses . 13, 1933, p. 60, doi : 10.15227 / orgsyn.013.0060 ; Coll. Vol. 2, 1943, p. 399 ( PDF ).
↑ Boublik, T .; Aim, K .: Heats of Vaporization of Simple Non-spherical Molecule Compounds in Collect. Czech. Chem. Commun. 37, 3513 (1972).
^ ^A ^b 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 E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.
↑ Carsten Schmuck, Bernd Engels, Tanja Schirmeister, Reinhold Fink: Chemistry for Medicine , Pearson Studies, p. 457, ISBN 978-3-8273-7286-4 .
↑ Greener Industry: Ethanoic Acid - Production Method: The Monsanto Process. Accessed May 14, 2019 .
^ PH List, L. Hörhammer: Chemicals and Drugs Part A: NQ . Springer-Verlag, 2013, ISBN 978-3-642-65035-2 , pp. 108 ( limited preview in Google Book search).

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Entry on iodomethane in the GESTIS substance database of the IFA , accessed on May 15, 2019(JavaScript required) .

[CRC90_6_188-2] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Permittivity (Dielectric Constant) of Gases, pp. 6-188.

[roempp-3] Entry on iodomethane. In: Römpp Online . Georg Thieme Verlag, accessed on September 19, 2014.

[CLP_100.000.745-4] Entry on Iodomethane 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 .

[5] Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 74-88-4 or iodomethane ), accessed on November 2, 2015.

[6] AS Carson, PG Laye, JB Pedley, Alison M. Welsby: The enthalpies of formation of iodomethane, diiodomethane, triiodomethane, and tetraiodomethane by rotating combustion calorimetry , in: The Journal of Chemical Thermodynamics , 1993 , 25 (2) , p. 261-269; doi : 10.1006 / jcht.1993.1025 .

[king-7] A ^b CS King, WW Hartman: Methyl Iodide In: Organic Syntheses . 13, 1933, p. 60, doi : 10.15227 / orgsyn.013.0060 ; Coll. Vol. 2, 1943, p. 399 ( PDF ).

[8] Boublik, T .; Aim, K .: Heats of Vaporization of Simple Non-spherical Molecule Compounds in Collect. Czech. Chem. Commun. 37, 3513 (1972).

[Stull-9] A ^b Stull, DR: Vapor Pressure of Pure Substances. Organic and Inorganic Compounds in Ind. Eng. Chem. 39 (1947) 517-540, doi : 10.1021 / ie50448a022 .

[Brandes-10] A ^b E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.

[Schmuck-11] Carsten Schmuck, Bernd Engels, Tanja Schirmeister, Reinhold Fink: Chemistry for Medicine , Pearson Studies, p. 457, ISBN 978-3-8273-7286-4 .

[12] Greener Industry: Ethanoic Acid - Production Method: The Monsanto Process. Accessed May 14, 2019 .

[P._H._List,_L._Hörhammer-13] PH List, L. Hörhammer: Chemicals and Drugs Part A: NQ . Springer-Verlag, 2013, ISBN 978-3-642-65035-2 , pp. 108 ( limited preview in Google Book search).