chromium

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Tetrakis(neopentyl)chromium is prepared essentially by a method disclosed in U.S. Pat. No. 3,875,132. The base catalyst is prepared by dispersing tetrakis(neopentyl)chromium in heptane solution onto Davison 952 MS-ID silica, predried at 1300° F. for 5 hours in a fluid bed, in such a ratio as to give 1% chromium by weight on the dry basis in the impregnated catalyst. The base catalyst thus prepared is activated, in one case, by the method of Example 8 and, in the other case, by the method of Example 9 which includes further treatment of the activated catalyst at 1200° F. for a period of 15 minutes with dry air. The base catalyst is prepared

Conditions: temp:150.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Chromium metal (1.0 g, 99.95% purity) pieces were suspended in water (20 mL) and hydrogen bis-triflimide (HNTf2) (5 g) was added. This mixture was heated under reflux for 144 hours. The resultant mixture was cooled, filtered and concentrated on a rotary evaporator to give a green solid. The solid were heated at 150° C. at 1 mmHg to remove the residual water and hydrogen bis-triflimide. The solid was thought to contain an oxo chromium bis-triflimide species CrO(NTf2) from the mass of HNTf2 produced in drying process. The unpurified chromium(III) bis-triflimide was found to display catalytic activity in Friedel-Crafts reactions, and was similar in activity to Zn(NTf2)2. This mixture was heated under reflux for 144 hours filtered concentrated on a rotary evaporator to give a green solid to remove the residual water and hydrogen bis-triflimide produced in drying process

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Four olefin polymerization catalyst samples were then prepared by slurrying 0.4 gram portions of each of the activated silica supports made as in the preceeding paragraph with 20 mg. portions of bis(cyclopentadienyl)chromium [II] (chromocene) in about 100 ml. of n-hexane. The slurries were stirred for about 30 minutes to allow the chromium compound to deposit on the activated supports. Control A was prepared as in the preceeding paragraph from silica treated as in A but without adding any (NH4)2SiF6. were then prepared Control A was prepared as in the preceeding paragraph from silica treated as in A but

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a wet chemical step, the cadmium stannate layer is treated with a solution containing chromium and/or chromium oxide, e.g. an aqueous solution of concentration from 1 to 10000 ppm chromium. Heat treatment at between about 100° C. and about 750° C. can be subsequently applied. In this way, either the cadmium stannate layer is impregnated with chromium/chromium oxide or a surface coating of chromium/chromium oxide is produced on the cadmium stannate layer. an aqueous solution of concentration from 1 to 10000 ppm chromium Heat treatment at between about 100° C. and about 750° C.