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CHAPTER 23 969 
 
Useful reagents 
 
The following is a list of reagents that appear in this chapter: 
 
Reagents Function 
Li (2 eq.) Used to convert an organohalide into an organolithium compound. 
RLi An organolithium reagent. A very strong nucleophile and a very strong base. 
Mg, Et2O Reagents for converting an organohalide into a Grignard reagent. 
RMgX A Grignard reagent. A very strong nucleophile and a very strong base. 
CuX (0.5 eq.) Used to convert an organolithium compound into a Gilman reagent. 
CH2I2, Zn-Cu, Et2O Reagents for a Simmons-Smith cyclopropanation. 
Bu3SnCl 
Used to convert an organolithium or organomagnesium compound into an 
organostannane. 
Pd(PPh3)4 
A catalyst used for coupling reactions, including Stille coupling, Suzuki 
coupling, Negishi coupling, and the Heck reaction. 
Pd(OAc)2 
A catalyst used for coupling reactions, including Stille coupling, Suzuki 
coupling, Negishi coupling, and the Heck reaction. 
 
Catechol borane. Used to convert an alkyne into a vinyl boronic ester. Also 
used to convert an alkene into an alkyl boronic ester. 
 
9-BBN. Used to convert an alkyne into a vinyl borane. Also used to convert an 
alkene into an alkyl borane. 
B(OMe)3 
Trimethylborate. Used to convert an aryllithium compound into an aryl boronic 
ester. 
ZnBr2 
Zinc dibromide. Used to convert an organolithium or organomagnesium 
compound into an organozinc compound. 
Zn, Et2O 
Zinc and diethyl ether. Used to convert an organolithium or organomagnesium 
compound into an organozinc compound. 
Grubbs catalyst 
Used to achieve alkene metathesis, including ring-opening metathesis and ring-
closing metathesis. 
 
Solutions 
 
23.1. The first compound is an organomagnesium 
compound (CMg bond), while the second compound is 
an organozinc reagent (CZn bond). We must compare 
these two CM bonds to determine which bond has 
greater ionic character. The difference in 
electronegativity between C (2.5) and Mg (1.2) is greater 
than the difference in electronegativity between C (2.5) 
and Zn (1.6). Therefore, the carbon atom of a CMg 
bond is expected to have a greater partial negative 
character, and thus be more nucleophilic than the carbon 
atom of the CZn bond. That is, organomagnesium 
compounds are expected be more nucleophilic than 
organozinc compounds. Indeed, they are. 
 
23.2. Compound A is formed when the iodide group (in 
4-iodotoluene) is replaced with a lithium atom, giving an 
organolithium compound: 
 
 
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