294-40-6

Basic information

• Product Name: Cyclopentasiloxane
• Synonyms: 1,3,5,7,9-Pentaoxa-2,4,6,8,10-pentasilacyclodecane;Jeesile CPS 312
• CAS NO: 294-40-6
• Molecular Formula: H10O5 Si5
• Molecular Weight: 230.504
• Mol File: 294-40-6.mol
• Article Data: 3

Chemical Properties

• CAS DataBase Reference: Cyclopentasiloxane(CAS DataBase Reference)
• NIST Chemistry Reference: Cyclopentasiloxane(294-40-6)
• EPA Substance Registry System: Cyclopentasiloxane(294-40-6)

Safety Data

• Hazardous Substances Data: 294-40-6(Hazardous Substances Data)

Synthetic route

Dichlorosilane (4109-96-0) → cyclotetrasiloxane + 1,1,3,3,5,5,7,7,9,9-decahydrocyclopentasiloxane (294-40-6) + 1,1,3,3,5,5,7,7,9,9,11,11-dodecahydro-cyclohexasiloxane (295-01-2)

Conditions	Yield
With water In dichloromethane hydrolysis H2SiCl2 in dichloromethane soln. either with stoich. amt. water at -30 to -20°C or by slow, controlled addn. slight excess water at 0°C; products isolated by GC;	A 6.1% B 22.6% C 12%

water (7732-18-5) + Dichlorosilane (4109-96-0) → cyclotetrasiloxane + 1,1,3,3,5,5,7,7,9,9-decahydrocyclopentasiloxane (294-40-6) + 1,1,3,3,5,5,7,7,9,9,11,11-dodecahydro-cyclohexasiloxane (295-01-2) + cyclooctasiloxane + cycloheptasiloxane (295-47-6)

Conditions	Yield
In diethyl ether SiH2Cl2 and ether was mixed at -40°C, warming to room temp., addn. of H2O dropwise over 7 min, stirring at room temp. for 30 min; further products; not isolated, detected by GLC;

water (7732-18-5) + Dichlorosilane (4109-96-0) → cyclotetrasiloxane + 1,1,3,3,5,5,7,7,9,9-decahydrocyclopentasiloxane (294-40-6) + 1,1,3,3,5,5,7,7,9,9,11,11-dodecahydro-cyclohexasiloxane (295-01-2) + cycloheptasiloxane (295-47-6)

Conditions	Yield
In pentane SiH2Cl2 and ether was mixed at -40°C, warming to room temp., addn. of H2O dropwise over 7 min, stirring at room temp. for 30 min; further products; not isolated, detected by GLC;

Dichlorosilane (4109-96-0) + zinc(II) carbonate (743369-26-8) → cyclotetrasiloxane + 1,1,3,3,5,5,7,7,9,9-decahydrocyclopentasiloxane (294-40-6) + 1,1,3,3,5,5,7,7,9,9,11,11-dodecahydro-cyclohexasiloxane (295-01-2)

Conditions	Yield
In hexane Product distribution / selectivity; Cooling;

Dichlorosilane (4109-96-0) + calcium carbonate → cyclotetrasiloxane + 1,1,3,3,5,5,7,7,9,9-decahydrocyclopentasiloxane (294-40-6) + 1,1,3,3,5,5,7,7,9,9,11,11-dodecahydro-cyclohexasiloxane (295-01-2)

Conditions	Yield
In ethyl acetate Cooling;

lithium carbonate (554-13-2) + Dichlorosilane (4109-96-0) → cyclotetrasiloxane + 1,1,3,3,5,5,7,7,9,9-decahydrocyclopentasiloxane (294-40-6) + 1,1,3,3,5,5,7,7,9,9,11,11-dodecahydro-cyclohexasiloxane (295-01-2)

Conditions	Yield
In ethyl acetate Cooling;

Upstream product

• 7732-18-5 water 
• 4109-96-0 Dichlorosilane 
• 743369-26-8 zinc(II) carbonate 
• 554-13-2 lithium carbonate 

Relevant articles and documents

Process for the manufacture of hydrogen-rich cyclosiloxane

The present invention relates to a for controlled synthesis of hydrogen-rich cyclosiloxanes of the (H2SiO)n type. where n is an integer equal to or greater than 3, by reacting: a.) a halosilane of the H2SiX2 type where X=halogen withb.) a lithium salt, copper(II) salt or a salt of a metal from main group 2 or transition group 2 of the periodic table of the elements, or a mixture of these salts. The ring size is advantageously adjustable to n=3, 4, 5, 6 (especially n=4 to 6), such that larger rings are not formed. In a particularly advantageous embodiment of the process, for the selective preparation of cyclohexasiloxane (H2SiO)6, after the reaction, the solvent is at least partly removed and then solvent is added again.

Cyclic polysiloxanes from the hydrolysis of dichlorosilane

The hydrolysis of H2SiCl2 in dichloromethane solution, either with a stoichiometric amount of water at -30 to -20°C or by slow, controlled addition of a slight excess of water at 0°C, results in the formation of siloxanes of type [H2SiO]n. In the volatile fraction oligomers with n from 4 up to 23 were found. Those with n = 4-6 were isolated by GC and characterized (1H and 29Si NMR, IR, n25D, mass spectroscopy). A brief study was made of the hydrolysis of MeSiHCl2 and Me2SiCl2 under comparable conditions.