Rudolph H Stehl

US Patent:

41993306, Apr 22, 1980

Filed:

Jan 22, 1979

Appl. No.:

6/005274

Inventors:

Terry J. Nestrick - Midland MI
Rudolph H. Stehl - Midland MI

Assignee:

The Dow Chemical Company - Midland MI

International Classification:

B01D 1508
B01J 3102

US Classification:

55 67

Abstract:

Highly effective chromatographic column packings are prepared by reacting hydroxyl groups on a silica surface with SiCl. sub. 4 and then reacting the chlorosilylated surface with a polyglycol or polymeric glycol ester in a slurry reaction. Residual chlorosilane groups on the reacted surface are neutralized by reaction with methanol or other lower alkanol. The resulting modified silica has a bonded, essentially monomolecular organic surface film which provides thermal stability, uniform efficiency, and rapid analysis when the material is used as a column packing in gas-liquid chromatography.

US Patent:

42760615, Jun 30, 1981

Filed:

May 14, 1980

Appl. No.:

6/149868

Inventors:

Terry J. Nestrick - Midland MI
Rudolph H. Stehl - Midland MI

Assignee:

The Dow Chemical Company - Midland MI

International Classification:

B01D 1508

US Classification:

55 67

Abstract:

Improved packings for columns useful in gas chromatography are made by a multistep process whereby polysiloxane molecules having various organic substituents are chemically bonded to the surface of a siliceous support. The process comprises one or more cycles of successive reactions with an activated support surface of silicon tetrachloride, an organic dichlorosilane, silicon tetrachloride a second time, a polysiloxane polyol, with intermediate hydrolyses where appropriate to provide reactive terminal silanol groups and a final capping reaction with an organic monochlorosilane. The packing as so prepared is further improved by coating with a conventional stationary phase.

US Patent:

42422272, Dec 30, 1980

Filed:

Jul 31, 1979

Appl. No.:

6/062380

Inventors:

Terry J. Nestrick - Midland MI
Rudolph H. Stehl - Midland MI

Assignee:

The Dow Chemical Company - Midland MI

International Classification:

B01J 3102
B01J 4900

US Classification:

252428

Abstract:

Improved packings for columns useful in gas chromatography are made by a multistep process whereby polysiloxane molecules having various organic substituents are chemically bonded to the surface of a siliceous support. The process comprises one or more cycles of successive reactions with an activated support surface of silicon tetrachloride, an organic dichlorosilane, silicon tetrachloride a second time, a polysiloxane polyol, with intermediate hydrolyses where appropriate to provide reactive terminal silanol groups and a final capping reaction with an organic monochlorosilane. The packing as so prepared is further improved by coating with a conventional stationary phase.