Schwartz reagent

Structural formula
General
Surname	Schwartz reagent
other names	Bis (cyclopentadienyl) zirconium chlorohydride
Molecular formula	C 10 H 11 ClZr
Brief description	white solid
External identifiers / databases
EC number	253-479-5
ECHA InfoCard	100,048,599
PubChem	21879930
Wikidata	Q412819
properties
Molar mass	257.87 g mol −1
Physical state	firmly
Melting point	> 300 ° C
solubility	reacts with water and ethanol
safety instructions
H and P phrases	H: 261-314
	P: 231 + 232-280-305 + 351 + 338-310-422
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

The Schwartz reagent is a chemical compound of zirconium from the group of metallocenes . It is used in organic synthesis for hydrozirconation and was named after the American chemist Jeffrey Schwartz .

history

The Schwartz reagent was first synthesized in 1970 by PC Wailes and H. Weigold. The compound got its name in 1974 when Jeffrey Schwartz developed hydrozirconation with the aid of bis (cyclopentadienyl) zirconium chlorohydride.

Extraction and presentation

The Schwartz reagent can be obtained by hydrogenating zirconocene dichloride with lithium aluminum hydride . The zirconocene dihydride that is also formed can be converted into the mixed compound by reaction with dichloromethane .

use

The Schwartz reagent is used for hydrozirconation. Here, a is carried addition of zirconium and hydrogen of the reagent to an alkene or alkyne . Subsequent oxidative degradation with suitable reagents such as oxygen or bromine can be used to obtain substituted alkanes. The reaction with oxygen results in alcohols , with bromine bromoalkanes .

In addition, various carboxamides , including N, N- alkylamides and Weinreb amides ( N , O -dimethylhydroxylamides), can be reduced to the corresponding aldehydes using the Schwartz reagent . This reaction tolerates many functional groups such as esters and proceeds with high yields under mild reaction conditions.

Individual evidence

↑ ^a ^b Stephen L. Buchwald, Susan J. LaMaire, Ralph B. Nielsen, Brett T. Watson, Susan M. King: Schwartz's reagent Template: link text check / apostrophe In: Organic Syntheses . 71, 1993, p. 77, doi : 10.15227 / orgsyn.071.0077 ; Coll. Vol. 9, 1998, p. 162 ( PDF ).
↑ ^a ^b Data sheet Schwartz reagent from AlfaAesar, accessed on July 6, 2010 ( PDF )(JavaScript required) .
↑ ^a ^b Data sheet bis (cyclopentadienyl) zirconium (IV) chloride hydride from Sigma-Aldrich , accessed on April 23, 2011 ( PDF ).
↑ PC Wailes, H. Weigold: Hydrido complexes of zirconium I. Preparation , in: Journal of Organometallic Chemistry , 1970 , 24 (2), pp. 405-411; doi : 10.1016 / S0022-328X (00) 80281-8 .
↑ Donald W. Hart, Jeffrey Schwartz: Hydrozirconation. Organic synthesis via organozirconium intermediates. Synthesis and rearrangement of alkylzirconium (IV) complexes and their reaction with electrophiles , in: J. Am. Chem. Soc. , 1974 , 96 (26), pp. 8115-8116; doi : 10.1021 / ja00833a048 .
↑ Christoph Elschenbroich: Organometallchemie. 6th edition, Teubner, Wiesbaden 2008, ISBN 978-3-8351-0167-8 , p. 479.
↑ Jonathan M. White, Ashok Rao Tunoori, Gunda I. Georg: A Novel and Expeditious Reduction of Tertiary Amides to Aldehydes Using Cp 2 Zr (H) Cl . In: Journal of the American Chemical Society . tape 122 , no. 48 , December 2000, ISSN 0002-7863 , p. 11995–11996 , doi : 10.1021 / ja002149g ( acs.org [accessed May 24, 2020]).

[orgsyn-1] Stephen L. Buchwald, Susan J. LaMaire, Ralph B. Nielsen, Brett T. Watson, Susan M. King: Schwartz's reagent Template: link text check / apostrophe In: Organic Syntheses . 71, 1993, p. 77, doi : 10.15227 / orgsyn.071.0077 ; Coll. Vol. 9, 1998, p. 162 ( PDF ).

[alfa-2] Data sheet Schwartz reagent from AlfaAesar, accessed on July 6, 2010 ( PDF )(JavaScript required) .

[Sigma-3] Data sheet bis (cyclopentadienyl) zirconium (IV) chloride hydride from Sigma-Aldrich , accessed on April 23, 2011 ( PDF ).

[4] PC Wailes, H. Weigold: Hydrido complexes of zirconium I. Preparation , in: Journal of Organometallic Chemistry , 1970 , 24 (2), pp. 405-411; doi : 10.1016 / S0022-328X (00) 80281-8 .

[5] Donald W. Hart, Jeffrey Schwartz: Hydrozirconation. Organic synthesis via organozirconium intermediates. Synthesis and rearrangement of alkylzirconium (IV) complexes and their reaction with electrophiles , in: J. Am. Chem. Soc. , 1974 , 96 (26), pp. 8115-8116; doi : 10.1021 / ja00833a048 .

[6] Christoph Elschenbroich: Organometallchemie. 6th edition, Teubner, Wiesbaden 2008, ISBN 978-3-8351-0167-8 , p. 479.

[7] Jonathan M. White, Ashok Rao Tunoori, Gunda I. Georg: A Novel and Expeditious Reduction of Tertiary Amides to Aldehydes Using Cp 2 Zr (H) Cl . In: Journal of the American Chemical Society . tape 122 , no. 48 , December 2000, ISSN 0002-7863 , p. 11995–11996 , doi : 10.1021 / ja002149g ( acs.org [accessed May 24, 2020]).