Search results
Results from the WOW.Com Content Network
Zinc is a strong reducing agent with a standard redox potential of −0.76 V. Pure zinc tarnishes rapidly in air, rapidly forming a passive layer. The composition of this layer can be complex, but one constituent is probably basic zinc carbonate, Zn 5 (OH) 6 CO 3. [8] The reaction of zinc with water is slowed by this passive layer.
Zinin reaction or Zinin reduction involves reduction of nitro aromatic compounds to the amines using sodium sulfide. [1] It is used to convert nitrobenzenes to anilines . [ 2 ] [ 3 ] The reaction selectively reduces nitro groups in the presence of other easily reduced functional groups (e.g., aryl halides and C=C bonds) are present in the molecule.
Related to the preparation of Lucas' reagent, tetrachlorozincates are often generated by combining hydrochloric acid and zinc chloride. A related anion is [Zn 2 Cl 6] 2−, in which again Zn(II) adopts a tetrahedral geometry. [2] Portion of the crystal structure of the salt hexaacetonitrilenickel(II) tetrachlorozincate ([Ni(CH 3 CN) 6] 2+ [ZnCl ...
The oxygen on an aldehyde or ketone coordinates to the zinc to form the six-member chair like transition state 3. A rearrangement occurs in which zinc switches to the aldehyde or ketone oxygen and a carbon-carbon bond is formed 4. Acid workup 5,6 removes zinc to yield zinc(II) salts and a β-hydroxy-ester 7. [5]
The reaction produces a primary, secondary, or tertiary alcohol via a 1,2-addition. The Barbier reaction is advantageous because it is a one-pot process: the organozinc reagent is generated in the presence of the carbonyl substrate. Organozinc reagents are also less water sensitive, thus this reaction can be conducted in water.
The reaction is named after its co-discoverer, John E. McMurry. The McMurry reaction originally involved the use of a mixture TiCl 3 and LiAlH 4, which produces the active reagents. Related species have been developed involving the combination of TiCl 3 or TiCl 4 with various other reducing agents, including potassium, zinc, and magnesium.
The Charette modification replaces the CH 2 I 2 normally found in the Simmons–Smith reaction with aryldiazo compounds, such as phenyldiazomethane, in Pathway A. [30] Upon treatment with stoichiometric amounts of zinc halide, an organozinc compound similar to the carbenoid discussed above is produced. This can react with almost all alkenes and ...
For commercial applications, some effort is made to avoid halide impurities by using acetate salts of zinc: [5] [6] Zn(CH 3 COO) 2 + HCN → Zn(CN) 2 + 2 CH 3 COOH. Zinc cyanide is also produced as a byproduct of certain gold extraction methods. Procedures to isolate gold from aqueous gold cyanide sometimes call for the addition of zinc: