Cyclotetrasiloxane, also known as octamethylcyclotetrasiloxane or D4, is a clear liquid with a molecular formula of C4H8O4Si4. It is commonly used as a silicone intermediate, serving as a building block for the synthesis of various silicone-based materials. Additionally, cyclotetrasiloxane finds applications as a lubricant, providing lubrication and surface protection. It is used in diverse industries, including cosmetics and personal care, electronics, and industrial chemicals. Its versatility makes it valuable in the production of silicone rubber, resins, and specialty chemicals.