Name | Methyl iodide |
Synonyms | CH3I Halon 10001 Iodomethane 10domethane Methyl iodide METHYLIODIDE,REAGENT Iodomethane, 2M solution in tert-butyl methyl ether |
CAS | 74-88-4 |
EINECS | 200-819-5 |
InChI | InChI=1/CH3I/c1-2/h1H3 |
Molecular Formula | CH3I |
Molar Mass | 141.94 |
Density | 2.28g/mLat 25°C(lit.) |
Melting Point | −64(lit.) |
Boling Point | 41-43°C |
Flash Point | −18°F |
Water Solubility | 14 g/L (20 ºC) |
Solubility | water: soluble14g/L at 20°C |
Vapor Presure | 24.09 psi ( 55 °C) |
Vapor Density | 4.89 (vs air) |
Appearance | Liquid |
Specific Gravity | 2.280 |
Color | Clear |
Odor | Sweet, ethereal odor (no threshold data available); inadequate warning properties |
Exposure Limit | TLV-TWA 2 ppm (~11 mg/m3) (ACGIH),5 ppm (MSHA and OSHA); carcinogenicity:Animal Limited Evidence (IARC), SuspectedHuman Carcinogen. |
Merck | 14,6087 |
BRN | 969135 |
PH | 5.2 (H2O, 25℃) |
Storage Condition | 2-8°C |
Stability | Light Sensitive |
Sensitive | Light Sensitive |
Refractive Index | n20/D 1.530 |
Physical and Chemical Properties | Colorless flammable body. Melting Point -66.45 ℃, boiling point of 42.4 ℃, relative density of 2.279(20/4 ℃), refractive index of 1.5317. With ethanol, ether miscible, soluble in acetone and benzene, slightly soluble in water. The light changed to red. |
Risk Codes | R21 - Harmful in contact with skin R23/25 - Toxic by inhalation and if swallowed. R37/38 - Irritating to respiratory system and skin. R40 - Limited evidence of a carcinogenic effect R11 - Highly Flammable R39/23/24/25 - R23/24/25 - Toxic by inhalation, in contact with skin and if swallowed. R38 - Irritating to the skin R20/22 - Harmful by inhalation and if swallowed. |
Safety Description | S36/37 - Wear suitable protective clothing and gloves. S38 - In case of insufficient ventilation, wear suitable respiratory equipment. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S9 - Keep container in a well-ventilated place. S24 - Avoid contact with skin. S16 - Keep away from sources of ignition. S7 - Keep container tightly closed. S60 - This material and its container must be disposed of as hazardous waste. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S33 - Take precautionary measures against static discharges. S23 - Do not breathe vapour. S20 - When using, do not eat or drink. S4 - Keep away from living quarters. |
UN IDs | UN 2644 6.1/PG 1 |
WGK Germany | 1 |
RTECS | PA9450000 |
FLUKA BRAND F CODES | 8 |
TSCA | Yes |
HS Code | 29033990 |
Hazard Class | 6.1 |
Packing Group | I |
Toxicity | LD50 orally in rats: 76 mg/kg; LD50 s.c. in mice: 0.78 mmoles/kg (IARC, 1986) |
colorless flammable liquid. Relative density 2. 279(20 ℃). Melting Point -66. 45 °c. Boiling point 42.4 °c. Refractive index 5317. Slightly soluble in water, with ethanol, ether miscible, soluble in acetone and benzene. The light changed to red.
results from the disproportionation of dimethyl sulfate.
products in the pharmaceutical industry for the production of iodomethylmethionine (Vitamin U), analgesics, antidotes and other drugs; In organic synthesis, used as methylating agent to synthesize iodoform; in addition, it is also used as a fire extinguishing agent.
inhalation of this product vapor can produce vertigo, Coma, confusion and other diseases; The eyes, skin irritation. Ammonia is an effective antidote for methyl iodide. The LD50 of rats after oral administration was 220mg/kg.
25kg or 50kg iron drum packaging or glass bottles for external use of wooden cases lined with bedding packaging. Store in a cool, ventilated room, away from heat source and fire, protected from light. With edible raw materials, oxidant Isolation storage.
Henry's Law Constant | 5.06 at 21 °C (Gan and Yates, 1996) |
(IARC) carcinogen classification | 3 (Vol. 41, Sup 7, 71) 1999 |
NIST chemical information | information provided by: webbook.nist.gov (external link) |
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
Overview | methyl iodide is a halogenated hydrocarbon, the molecular formula is CH3I, MeI, is an iodine substitution of methane. Boiling point 42.4 ℃, relative density 2.279(20/4 ℃), room temperature for the density of volatile liquids, dipole moment 1.59D, refractive index 1.5304(20 ℃, D), 1.5293(21 C, D). Methyl iodide can be miscible with common organic solvents, slightly soluble in water, soluble in ethanol, ether, pure colorless, odorous, exposed to sunlight will decompose I2 and purple, this can be removed by the addition of metallic copper. Methyl iodide is present in small amounts in paddy fields. Methyl iodide is a commonly used methylation reagent in organic synthesis. Methyl iodide is an ideal substrate for SN2 substitution reaction. On the one hand, because of its small steric hindrance effect, it is convenient for nucleophilic reagent to attack; On the other hand, iodine ion is a good leaving group. Therefore, methyl iodide can be used to carry out the methylation reaction of phenol and carboxylic acid, and the alkali (K2CO3 or Li2CO3) removes the acidic proton of carboxylic acid or phenol to form carboxylate ion and phenol salt ion, the SN2 reaction then occurs as a nucleophile. |
methyl iodide prepared in laboratory | when iodine is added to the mixture of methanol and red phosphorus, an exothermic reaction will occur to generate methyl iodide: 5 CH3OH P 2.5 I2 → 5 CH3I H3PO4 H2O reaction generated three phosphorus iodide intermediate, played the role of iodination reaction with methanol. Methyl iodide can also be prepared by the reaction of dimethyl sulfate and potassium iodide in the presence of calcium carbonate:(CH3O)2SO2 KI → K2SO4 2 CH3I the reaction product is distilled first, and then washed with Na2S2O3, water and Na2CO3 solution, pure methyl iodide can be obtained. |
methylation reaction | methyl iodide and dimethyl carbonate, dimethyl sulfate, methyl triflate are common methylation reagents, iodine is a "soft" anion, so the methylation reaction in which methyl iodide is involved should also occur in the softer segment of the two nucleophiles. For example, in the reaction with thiocyanate ion, S is softer, so the possibility of attack from S atom is higher than that from N atom, and the product is mainly methyl thiocyanate (CH3SCN) instead of CH3NCS. Further, the reaction between methyl iodide and an enol salt formed from a 1, 3-dicarbonyl compound can also be explained by the above theory. Relative to the carbon atom, the oxygen atom is relatively hard, and the reaction in which methyl iodide participates also almost all produce the product of C- methylation. Methyl iodide methylation has the following disadvantages: its relative molecular mass is large, the mass of one mole of MeI is almost equal to the mass of three moles of CH3Cl; Iodine compounds are still more expensive than chloride and bromide, as a result, the cheaper dimethyl sulfate in industry still has many applications, although its toxicity is much higher than that of methyl iodide; Iodine leaving groups may cause side reactions; methyl iodide is more toxic than the corresponding chlorine compounds and bromine compounds, which is very unfavorable to the production workers. Therefore, in the selection of methylating agents, it is usually necessary to consider the price, source, toxicity, chemical selectivity and ease of reaction and many other factors. |
Use | used as a methylating agent used as a fungicide, herbicide, insecticide or nematicide and a fire-extinguishing agent used as a soil disinfectant, methyl iodide is also used in microscopy as an alternative to methyl bromide (banned by the Montreal Convention) because of its refractive index. The pharmaceutical industry is used for the production of iodomethylmethionine (Vitamin U), analgesics, antidotes and other drugs, and is also used for organic synthesis as methylation reagent, fire extinguishing agent, etc. used as analytical reagent, also used in pharmaceutical industry mainly used as methylation reagent, used in the pharmaceutical industry for iodomethylmethionine (Vitamin U), analgesics, production of phosphoric acid drugs for antidotes |
production method | is obtained by halogenation of dimethyl sulfate. Water, potassium iodide and calcium carbonate were sequentially added to the reaction pot, and the mixture was stirred and heated to completely dissolve the potassium iodide. The temperature was raised to 60-65 ° C., and dimethyl sulfate was added dropwise. The generated methyl iodide was gradually distilled out, and the distillate was collected. When further refined, it can be dried by anhydrous calcium chloride, and several grains of potassium iodide are added for distillation, and the fraction at 41-43 ° C. Can be collected, and the yield is about 90%. |
category | toxic substances |
toxicity grade | high toxicity |
Acute toxicity | inhalation-rat LC50: 1300 mg/m3/4 H; Intraperitoneal-mouse LD50:172 mg/kg |
stimulation data | Skin-rabbit 1000 mg/30 min mild |
flammability hazard characteristics | pyrolysis of toxic iodide gases |
storage and transportation characteristics | The warehouse is ventilated and dried at low temperature; It is stored separately from oxidants and food additives |
fire extinguishing agent | foam, water mist, sand |
Occupational Standard | TLV-TWA 2 PPM (10 mg/m3) |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
immediate life-and health-threatening concentration | 100 ppm |