Hexamethyldisiloxane

The IUPAC name of Hexamethyldisiloxane is trimethyl(trimethylsilyloxy)silane. With the CAS registry number 107-46-0 and EINECS 203-492-7, it is also named as Disiloxane, hexamethyl-. The product's categories are Siloxanes; Organics; Si (Classes of Silicon Compounds); Silicon Compounds (for Synthesis); Si-O Compounds; Synthetic Organic Chemistry. It is colorless or yellowish transparent liquid which is stable, but moisture sensitive. It is also highly flammable, so people should keep it away from sources of ignition. When heated to decomposition it emits acrid smoke and fumes. Additionally, this chemical should be sealed in the container and stored in the cool, well-ventilated and dry place.

The other characteristics of this product can be summarized as: (1)ACD/LogP: 4.21; (2)# of Rule of 5 Violations: 0; (3)ACD/LogD (pH 5.5): 4.2; (4)ACD/LogD (pH 7.4): 4.2; (5)ACD/BCF (pH 5.5): 923.51; (6)ACD/BCF (pH 7.4): 923.51; (7)ACD/KOC (pH 5.5): 4615.97; (8)ACD/KOC (pH 7.4): 4615.97; (9)#H bond acceptors: 1; (10)#H bond donors: 0; (11)#Freely Rotating Bonds: 2; (12)Polar Surface Area: 9.23 Å²; (13)Index of Refraction: 1.393; (14)Molar Refractivity: 49.02 cm³; (15)Molar Volume: 205.4 cm³; (16)Polarizability: 19.43×10^-24 cm³; (17)Surface Tension: 15.6 dyne/cm; (18)Enthalpy of Vaporization: 32.61 kJ/mol; (19)Vapour Pressure: 41.4 mmHg at 25°C; (20)Rotatable Bond Count: 2; (21)Exact Mass: 162.089618; (22)MonoIsotopic Mass: 162.089618; (23)Topological Polar Surface Area: 9.2; (24)Heavy Atom Count: 9; (25)Complexity: 76.2.

Preparation of Hexamethyldisiloxane: Adding 62.49g (0.575mol) trimethylchlorosilane to the solution of 72.7g (0.06mol) N, N-dimethylaniline and 7g water and refluxing 1h. Using atmospheric distillation to collect fractions of 98-101 °C. After drying. we can get 43-44g product. The yield is 92-94%. 2(CH₃)₃SiCl+H₂O→(CH₃)₃SiO(CH3)3Si+2HCl

Uses of Hexamethyldisiloxane: It is mainly used as source of the trimethylsilyl functional group (-Si(CH₃)₃) in organic synthesis. It is also used in liquid bandages (spray on plasters) such as cavilon spray, to protect damaged skin from irritation from other bodily fluids. What's more, it is used as a solvent and as a reagent in organic synthesis. For example: it can react with 4-benzoylamino-1H-pyrimidin-2-one to get N-(2-oxo-1-trimethylsilanyl-1,2-dihydro-pyrimidin-4-yl)-benzamide. This reaction which is a kind of alkylation needs reagent (NH4)₂SO₄ and solvent acetonitrile at temperature of 140 °C. The reaction time is 20 hours. The yield is 37%.

People can use the following data to convert to the molecule structure. 
1. SMILES:O([Si](C)(C)C)[Si](C)(C)C
2. InChI:InChI=1/C6H18OSi2/c1-8(2,3)7-9(4,5)6/h1-6H3
3. InChIKey:UQEAIHBTYFGYIE-UHFFFAOYAL

The following are the toxicity data which has been tested.