محلول تترا متیل آمونیوم هیدروکسید 25%

Tetramethylammonium hydroxide solution 25% is a clear, colorless to slightly yellow aqueous solution of the quaternary ammonium base tetramethylammonium hydroxide (TMAH). It is widely used in the semiconductor industry, organic synthesis, and as a strong, non-metallic base in various chemical processes.

🏭⚗️ Production
Tetramethylammonium hydroxide is typically synthesized by methylating ammonia using methyl halides, followed by treatment with a hydroxide source, such as silver oxide or ion-exchange resins, to replace the halide with a hydroxide ion. The resulting tetramethylammonium hydroxide is then diluted to desired concentrations, such as 25%, for commercial and laboratory use. The solution is usually stabilized and stored under strict conditions due to its toxicity and reactivity.

🔬 Properties
The chemical formula of tetramethylammonium hydroxide is (CH₃)₄NOH, with a molar mass of approximately 91.15 g/mol (for the anhydrous base). The 25% solution contains about 250 g of TMAH per liter of water. It is a strong base, highly soluble in water and alcohols, and exhibits high conductivity. The solution is corrosive, has a strong ammonia-like odor, and may darken slightly over time due to decomposition. TMAH decomposes at elevated temperatures and can emit toxic fumes if heated or mixed with incompatible substances.

🧪 Applications
Tetramethylammonium hydroxide 25% solution is widely used in semiconductor fabrication, particularly in anisotropic wet etching of silicon and in photoresist development processes. In organic synthesis, it serves as a non-metallic, strong base for deprotonation and quaternization reactions. It is also used in analytical chemistry, surface cleaning, catalysis, and in the preparation of ionic liquids and other quaternary ammonium compounds. Additionally, it is employed in polymer synthesis and in the preparation of advanced electronic materials.

⚠️ Safety
Tetramethylammonium hydroxide is highly toxic and corrosive, especially in concentrated solutions like 25%. It can cause severe burns to the skin and eyes and is lethal if ingested or absorbed through the skin in sufficient quantities. Inhalation of vapors or aerosols may lead to respiratory tract damage. Extreme care must be taken when handling the solution. Full personal protective equipment—including gloves, chemical splash goggles, and lab coats—must be used, along with appropriate ventilation or a fume hood. TMAH should be stored in tightly sealed containers in a cool, dry, and well-ventilated area away from acids and incompatible materials.