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Iodomethane
IUPAC name Iodomethane
Other names Methyl iodide, Monoiodomethane, Methyl iodine, MeI, Halon 10001, UN 2644
Identifiers
CAS number [74-88-4]
PubChem 6328
EINECS number 200-819-5
RTECS number PA9450000
SMILES CI
InChI 1/CH3I/c1-2/h1H3
Properties
Molecular formula CH3I
Molar mass 141. IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to PubChem is a Database of chemical Molecules The system is maintained by the National Center for Biotechnology Information (NCBI a component The EINECS number (for European Inventory of Existing Chemical Substances) is a registry number given to each Chemical substance commercially available in the Registry of Toxic Effects of Chemical Substances ( RTECS) is a Database of Toxicity information compiled from the open scientific literature without reference The IUPAC International Chemical Identifier ( InChI, pronounced "INchee" is a textual Identifier for Chemical substances designed to provide a A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) 94 g/mol
Appearance Clear colourless liquid with acrid odor
Density 2. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 2789 g/cm3 at 20 °C
Melting point

-66. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. 45 °C (206. 70 K)
Boiling point

42. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid 43 °C (315. 58 K)
Solubility in water 14 g/l at 20 °C
log P 1. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Water is a common Chemical substance that is essential for the survival of all known forms of Life. In the fields of organic and Medicinal chemistry, a partition (P or distribution coefficient (D is 51
Vapor pressure 50 kPa at 20 °C

53. Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium 32 at 25. 3 °C 166. 1 kPa at 55 °C
Hazards
EU classification Toxic (T), Carc. Cat. 3
NFPA 704
0
3
1
 
R-phrases R21, R23/25, R37/38, R40
S-phrases (S1/2), S36/37, S38, S45
Flash point -28 °C
Autoignition
temperature		 352 °C
Explosive limits 8. Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws regulations and administrative provisions relating to the classification packaging and labelling The term carcinogen refers to any substance Radionuclide or radiation that is an agent directly involved in the promotion of Cancer or in the fatation of its propagation Symbolism The four divisions are typically color-coded with blue indicating level of Health Hazard, red indicating R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. The flash point of a flammable liquid is the lowest Temperature at which it can form an ignitable mixture in air The autoignition temperature or kindling point of a substance is the lowest temperature at which it will spontaneously ignite in a normal atmosphere without an external 5 - 66%
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Iodomethane, commonly called methyl iodide and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. In Chemistry, the standard state of a material is its state at 1 bar (100 Kilopascals exactly In Chemistry, a methyl group is a Hydrophobic Alkyl Functional group named after Methane (4 A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. This dense volatile liquid is related to methane by replacement of one hydrogen atom by an atom of iodine and its dipole moment is 1. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a 59 D. Refractive index is 1. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium 5304 (20 °C, D), 1. 5293 (21 °C, D). It is miscible with common organic solvents. It is colourless, although upon exposure to light, samples develop a purplish tinge caused by the presence of I2. Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Storage over copper metal absorbs the iodine. Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Methyl iodide is widely used in organic synthesis to deliver a methyl group, via the transformation called methylation. Organic synthesis is a special branch of Chemical synthesis and is concerned with the construction of Organic compounds via Organic reactions Organic In Chemistry, a methyl group is a Hydrophobic Alkyl Functional group named after Methane (4 Methylation is a term used in the chemical sciences to denote the attachment or substitution of a methyl group on various substrates. It is naturally emitted by rice plantations in small amounts. Rice is a Cereal foodstuff which forms an important part of the diet of many people worldwide and as such it is a staple food for many [1]

Contents

Chemical properties

Methyl iodide is an excellent substrate for SN2 substitution reactions. It is sterically open for attack by nucleophiles, and iodide is a good leaving group. See also Intramolecular forces ' Steric effects arise from the fact that each Atom within a Molecule occupies a certain In Chemistry, a nucleophile (literally nucleus lover as in nucleus and phile) is a Reagent that forms a Chemical bond to An iodide Ion is an iodine atom with a &minus1 charge. Compounds with iodine in formal Oxidation state &minus1 are called iodides A leaving group is an Atom or group of atoms that detaches from a chemical substance For example, it can be used for the methylation of phenols or carboxylic acids:[2]

Methylation of a carboxylic acid or phenol with MeI

In these examples, the base (K2CO3 or Li2CO3) removes the acidic proton to form the carboxylate or phenoxide anion, which serves as the nucleophile in the SN2 substitution. Phenol, is a toxic colourless Crystalline Solid with a sweet tarry odor commonly referred to as a "hospital smell" Carboxylic acids are Organic acids characterized by the presence of a Carboxyl group, which has the formula -C(=OOH usually written -COOH or -CO2H In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and Carbonate of potash redirects here For one of potassium carbonate's impure forms see Potash. Lithium carbonate is a Chemical compound with the formula Li2CO3

Iodide is a "soft" anion which means that methylation with MeI tends to occur at the "softer" end of an ambidentate nucleophile. The HSAB concept is an Acronym for 'hard and soft Acids and bases. In Chemistry, a nucleophile (literally nucleus lover as in nucleus and phile) is a Reagent that forms a Chemical bond to For example, reaction with thiocyanate ion favours attack at S rather than "hard" N, leading mainly to methyl thiocyanate (CH3SCN) rather than CH3NCS. Thiocyanate (also known as sulphocyanate or thiocyanide or rhodanide) is the anion − Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 This behavior is relevant to the methylation of stabilized enolates such as those derived from 1,3-dicarbonyl compounds. Methylation is a term used in the chemical sciences to denote the attachment or substitution of a methyl group on various substrates. Enols (also known as alkenols) are Alkenes with a Hydroxyl group affixed to one of the carbon atoms composing the Double bond. Methylation of these and related enolates can occur on the harder oxygen atom or the (usually desired) carbon atom. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the With methyl iodide, C-alkylation nearly always predominates.

MeI is also an important precursor to methylmagnesium iodide or "MeMgI", which is a common reagent. The Grignard reaction, named for the French chemist François Auguste Victor Grignard, is an organometallic Chemical reaction in which Alkyl - Because MeMgI forms readily, it is often prepared in instructional laboratories as an illustration of Grignard reagents. The Grignard reaction, named for the French chemist François Auguste Victor Grignard, is an organometallic Chemical reaction in which Alkyl - The use of MeMgI has been somewhat superseded by the commercially available methyl lithium. Methyllithium is an Organolithium reagent with the empirical formula CH3Li

In the Monsanto process, MeI forms in situ from the reaction of methanol and hydrogen iodide. The Monsanto process is an important method for the manufacture of Acetic acid. Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound Hydrogen iodide (HI is a Diatomic molecule. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a Strong acid. The CH3I then reacts with carbon monoxide in the presence of a rhodium complex to form acetyl iodide, the precursor to acetic acid after hydrolysis. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Rh redirects here For other uses see Rh (disambiguation Rhodium (ˈroʊdiəm is a Chemical element with the symbol Acetyl iodide, C2H3IO also known as ethanoyl iodide, is an Acyl halide derived from Acetic acid. Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste Hydrolysis is a Chemical reaction during which one or more water molecules are split into hydrogen and hydroxide ions which may go on to participate in further reactions Most acetic acid is prepared by this method.

MeI hydrolyzes at 270 °C forming hydrogen iodide, carbon monoxide and carbon dioxide. Hydrogen iodide (HI is a Diatomic molecule. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a Strong acid. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single

Preparation

Iodomethane is formed via the exothermic reaction that occurs when iodine is added to a mixture of methanol with red phosphorus:[3]

5 CH3OH + P + 2. An exothermic reaction is a Chemical reaction that releases Heat. Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 5 I2 → 5 CH3I + H3PO4 + H2O

The iodinating reagent is phosphorus triiodide that is formed in situ. Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Phosphoric acid, also known as orthophosphoric acid or phosphoric(V acid, is a mineral (inorganic acid having the Chemical formula Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as Phosphorus triiodide (PI3 is an unstable red solid which reacts violently with water Alternatively, it is prepared from the reaction of dimethyl sulfate with potassium iodide in the presence of calcium carbonate:[3]

(CH3O)2SO2 + KI → K2SO4 + 2 CH3I

The CH3I can easily be purified by distillation followed by washing with Na2S2O3 (to remove iodine) and then water, aq. Na2CO3. Dimethyl sulfate is a Chemical compound with formula (CH3O2SO2 Calcium carbonate is a Chemical compound with the Chemical formula Ca[[Carbon C]] O 3 Sodium thiosulfate ( Na 2 S 2 O 3 is a colorless Crystalline compound that is more familiar as the Pentahydrate Sodium carbonate (also known as washing soda or soda ash), is a Sodium Salt of Carbonic acid.

Methyl iodide can be formed during nuclear accidents by the reaction of organic matter with the "fission iodine. In Nuclear physics, a nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different from the initial particles Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may "

Choice of iodomethane as a methylating agent

Iodomethane is an excellent reagent for methylation, but there are some disadvantages to its use. It has a high equivalent weight: one mole of MeI weighs almost three times as much as one mole of methyl chloride. Chloromethane, also called Methyl chloride, R-40 or HCC 40 is a Chemical compound of the group of Organic compounds called Haloalkanes. However, the chloride is a gas (as is methyl bromide), making it more awkward to work with than liquid MeI. The Chemical compound bromomethane, commonly known as methyl bromide, is an organic Halogen compound with formula C[[Hydrogen Methyl chloride is a poorer methylating reagent than MeI, though it is often adequate.

Iodides are generally expensive relative to the more common chlorides and bromides, though iodomethane is reasonably affordable; on a commercial scale the toxic dimethyl sulfate is preferred, since it is both cheap and liquid. Dimethyl sulfate is a Chemical compound with formula (CH3O2SO2 The iodide leaving group in MeI may cause side reactions, as it is a powerful nucleophile. Finally, being highly reactive, MeI is more dangerous for laboratory workers than related chlorides and bromides. When considering alternatives to MeI, it is necessary to consider cost, handling, risk, chemical selectivity, and ease of reaction work-up.

Uses

Besides use as a methylation agent, there have been proposals of its use as a fungicide, herbicide, insecticide or nematicide and as a fire extinguisher. Fungicides are Chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores A herbicide is used to kill unwanted Plants Selective herbicides kill specific targets while leaving the desired Crop relatively unharmed An insecticide is a Pesticide used against Insects in all developmental forms A nematicide is a type of Chemical Pesticide used to kill Parasitic Nematodes (roundworms A fire extinguisher is an Active fire protection device used to extinguish or control small fires often in emergency situations Further it can be used as a soil disinfectant, replacing bromomethane (which was banned under the Montreal Protocol), and in microscopy due to properties related to refraction index. The Chemical compound bromomethane, commonly known as methyl bromide, is an organic Halogen compound with formula C[[Hydrogen For other similarly-named agreements see Montreal Convention (disambiguation. In a controversial October 2007 decision, the United States Environmental Protection Agency approved its use as a soil fumigant in some cases, although it cannot yet be used in California (a major potential market) due to lack of state approval. [4]

Toxicity and Biological effects

Iodomethane has an LD50 for oral administration to rats 76 mg/kg, and in the liver it undergoes rapid conversion to S-methylglutathione. In Toxicology, the median lethal dose, LD50 (abbreviation for “Lethal Dose 50%” or LCt50 (Lethal Concentration & Time of a The liver is a vital organ in the human body and is present in Vertebrates and some other animals Glutathione ( GSH) is a Tripeptide. It contains an unusual Peptide linkage between the amine group of Cysteine and the Carboxyl [5] Iodomethane is a possible carcinogen based on its IARC, ACGIH, NTP, or EPA classification. According to IARC it is classified as a group 3 substance (Group 3:The agent is not classifiable as to its carcinogenicity to humans).

Breathing iodomethane fumes can cause lung, liver, kidney and central nervous system damage. It causes nausea, dizziness, coughing and vomiting. Prolonged contact with skin causes burns. Massive inhalation causes pulmonary edema. Pulmonary Edema (American English or oedema (British English is swelling and/or fluid accumulation in the Lungs It leads to impaired gas exchange and may cause

See also

Methylating reagents

References

  1. ^ K. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane Halomethane compounds are molecules of Methane ( C[[hydrogen H]]4 with one or more of the Hydrogen atoms replaced with Halogen atoms Fluoromethane, also known as methyl fluoride, Freon 41, Halocarbon-41 and HFC-41, is a non-toxic liquefiable and flammable Chloromethane, also called Methyl chloride, R-40 or HCC 40 is a Chemical compound of the group of Organic compounds called Haloalkanes. The Chemical compound bromomethane, commonly known as methyl bromide, is an organic Halogen compound with formula C[[Hydrogen Diiodomethane or methylene iodide is liquid Halomethane insoluble in water soluble in Ether and Alcohol. The term 'iodoform' was also used in World War II to refer to Group keys sent to agents in Europe by the Special Operations Executive this usage is unrelated to the chemical Carbon tetraiodide is CI4, a Tetrahalomethane. Being bright red it is a relatively rare example of a highly colored methane derivative Dimethyl carbonate, often abbreviated DMC, is a flammable clear liquid boiling at 90 °C insoluble in water Dimethyl sulfate is a Chemical compound with formula (CH3O2SO2 R. Redeker, N. -Y. Wang, J. C. Low, A. McMillan, S. C. Tyler, and R. J. Cicerone (2000). "Emissions of Methyl Halides and Methane from Rice Paddies". Science 290: 966–969. Science is the Academic journal of the American Association for the Advancement of Science and is considered one of the world's most prestigious Scientific doi:10.1126/science.290.5493.966. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  2. ^ Avila-Zárraga, J. G. , Martínez, R. (January 2001). "Efficient methylation of carboxylic acids with potassium hydroxide/methyl sulfoxide and iodomethane". Synthetic Communications 31 (14): 2177–2183. doi:10.1081/SCC-100104469. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  3. ^ a b King, C. S. ; Hartman, W. W. (1943). "Methyl Iodide". Org. Synth.; Coll. Organic Syntheses is a Scientific journal that since 1921 has provided the Chemistry community with annual collections of detailed and checked procedures Vol. 2: 399.  
  4. ^ "EPA approves new pesticide despite scientists' concerns", Los Angeles Times, October 6, 2007. The Los Angeles Times (also known as the LA Times) is a daily Newspaper published in Los Angeles California and distributed Events 105 BC - Battle of Arausio: The Cimbri inflict the heaviest defeat on the Roman army of Gnaeus Mallius Maximus Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.  
  5. ^ Johnson, M. K. (1966). "Metabolism of iodomethane in the rat". Biochem. J. 98: 38–43. The Biochemical Journal ( Biochem J or BJ is a peer-reviewed academic journal which covers all aspects of Biochemistry, as well as cell and Molecular  

External links

The National Institute for Occupational Safety and Health (or NIOSH) is the United States federal agency responsible for conducting research and making recommendations

Dictionary

iodomethane

-noun

  1. (organic chemistry) The aliphatic halogenated hydrocarbon CH3I that is used in organic synthesis to introduce a methyl group into compounds
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