Name | Tetramethyl ammoniumhydroxid pentahydrate |
Synonyms | TMAH Pentahydrate N,N,N-trimethylmethanaminium hydroxide Tetramethylammonium Hydroxide-D135 D2O Tetramethyl ammoniumhydroxid pentahydrate Tetramethylammonium hydroxide pentahydrate Methanaminium, N,N,N-trimethyl-, hydroide, pentahydrate |
CAS | 10424-65-4 |
EINECS | 629-762-8 |
InChI | InChI=1/C4H12N.6H2O/c1-5(2,3)4;;;;;;/h1-4H3;6*1H2/q+1;;;;;;/p-1 |
InChIKey | MYXKPFMQWULLOH-UHFFFAOYSA-M |
Molecular Formula | C4H23NO6 |
Molar Mass | 181.23 |
Density | 1.829 |
Melting Point | 67-70°C(lit.) |
Water Solubility | soluble |
Vapor Presure | 97 mm Hg ( 20 °C) |
Vapor Density | 1.1 (vs air) |
Appearance | Hygroscopic Crystals |
Color | White |
Odor | Ammonia like |
Merck | 14,9224 |
BRN | 3714235 |
Storage Condition | 0-6°C |
Stability | Stable. Incompatible with strong oxidizing agents, strong acids. |
Sensitive | Air Sensitive & Hygroscopic |
Explosive Limit | 36% |
Physical and Chemical Properties | Colorless crystals (often containing three, five and other crystal water), very easy to absorb moisture, in the air can quickly absorb carbon dioxide, 130 deg C when the decomposition of methanol and trimethylamine, usually used 10%, 25% water (or alcohol) solution and compound containing water of crystallization. |
Risk Codes | R24/25 - R34 - Causes burns R44 - Risk of explosion if heated under confinement R20/21/22 - Harmful by inhalation, in contact with skin and if swallowed. |
Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) |
UN IDs | UN 3423 8/PG 2 |
WGK Germany | 1 |
RTECS | PA0875000 |
FLUKA BRAND F CODES | 3-34 |
TSCA | Yes |
HS Code | 29239000 |
Hazard Class | 8 |
Packing Group | II |
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
Overview | tetramethylammonium hydroxide (TMAH) is the strongest organic base, colorless, odorless. At room temperature, its vapor pressure is low, and it is completely decomposed and gasified at 135~145, and there is no trace residue in the low temperature treatment of high purity products at 140. Tetramethylammonium hydroxide solution is colorless, transparent and slightly ammonia-odorous. The pH value of 1(wt)% solution is 12.9, which is a strong alkali with the same strength as caustic alkali. The aqueous solution of tetramethylammonium hydroxide is concentrated under reduced pressure to obtain 5 hygroscopic needle crystals of crystal water (mp,63oC), and then the concentration and dehydration are continued to change into 3 crystals of crystal water (mp,63oC), then into a water of crystallization of tetramethylammonium hydroxide, 135 ~ 140oC decomposition of trimethylamine and dimethyl ether. |
Use | tetramethylammonium hydroxide is an organic base, which has a very wide range of uses in the field of industrial research. In China, tetramethylammonium hydroxide is mainly used as the main catalyst in the synthesis of silicone products, such as silicone oil, silicone rubber, silicone resin, etc. Although the dosage is not large, it has great influence on the yield and quality of the product. Foreign tetramethylammonium hydroxide is mainly used in polyester polymer, textile, plastic products, food, leather, wood processing, electroplating, microorganism, etc. At present, this product has entered the field of cutting-edge technology, such as in the printing of circuit boards and the manufacturing of microscopes, it can be used as cleaning agent for integrated circuit board and anisotropic etchant for Si-SiO2 interface in semiconductor micromachining technology. With the development of science and technology, the requirement of this type of chemical reagent is increasing day by day, which puts forward higher requirements for the quality and quantity of tetramethylammonium hydroxide. as silicone rubber, methyl silicone oil additives and polarographic analysis reagents. In the aspect of silicone, as the catalyst of dimethyl silicone oil, benzyl silicone oil, silicone diffusion pump oil, solvent-free silicone molding compound, silicone resin silicone rubber and the like. In the analysis, as a polarographic reagent, in the product purification as ashless alkali to precipitate many metal elements, in the organic silicon wafer production is often used as a computer silicon wafer surface brightener, cleaning agents and touch agents. Tetramethylammonium hydroxide as a catalyst, its advantage is, after the reaction is heated to raise the temperature, can be decomposed into gas and drive away does not remain in the product. |
preparation method | There are many preparation methods of tetramethylammonium hydroxide, which are generally generated by reacting tetramethylammonium chloride with silver oxide by using silver oxide method. However, the process of preparing tetramethylammonium hydroxide by this method is complicated, the raw material silver oxide is expensive, and the obtained product contains high impurity ions, such as halogen ions, alkali metal ions, etc, it seriously affects the characteristics of silicone products, and can not meet the requirements of cleaning and corrosion in the electronic field. The new technology of preparing tetramethyl ammonium hydroxide by electrolysis was adopted abroad from the 70's, and the silver oxide method was gradually replaced. The products prepared by electrolysis have good quality and low cost, which can not only meet the needs of silicone production, but also enter the field of electronic industry. |
Brief description of electrolysis process | 1, the principle of using tetramethylammonium chloride as the raw material is that under the action of the electric field force, the chloride ions in the aqueous solution in the anode chamber of the electrolytic cell migrate to the anode direction until the chlorine gas is discharged on the anode. At the same time, due to the selective permeability of the ion exchange membrane, chloride ions cannot diffuse through the ion exchange membrane, and only tetramethylammonium ions can selectively penetrate into the cathode chamber and are enriched therein. The water molecules in the cathode compartment of the electrolytic cell are decomposed into hydrogen and hydroxide ions at the cathode. The latter is combined with the tetramethylammonium ion which migrates from the anode compartment to form tetramethylammonium hydroxide. The concentration of tetramethylammonium hydroxide increased with the increase of the amount of electricity, and finally reached the expected crude concentration. Anode electrochemical reaction:(CH3)4NCl →(CH3)4N Cl ˉ 2Cl ˉ- 2e → Cl2 cathode electrochemical reaction: H2O → H OH ˉ(CH3)4N OH → →(CH3)4NOH2H 2e → H2 ↑ Total reaction: 2(CH3)4NCl 2H2O → 2(CH3)4NOH H2 ↑ Cl2 hydrogen generated in electrolysis, the generated chlorine gas is absorbed by alkali solution to generate sodium hypochlorite, which is the main raw material of bleaching powder. Therefore, the method for preparing tetramethylammonium hydroxide is simple, high purity and no environmental pollution. 2, four methyl ammonium bicarbonate as the raw material electrolysis principle is similar to the four methyl ammonium chloride as the raw material, but no chlorine gas is generated, the anode produces carbon dioxide and oxygen. Total reaction:(CH3)4NHCO3 H2O(CH3)4NOH CO2 ↑h2 |
autoignition temperature | 878 ° F. |