Carbene Formation

Question 1

3 ways

Answer 1

diazomethane (CH2N2)

Simmons-Smith (CH2I2, Zn(Cu))

alpha-elimination, haloethanes (CHCl3, KOH)

Question 2

diazomethane

Answer 2

CH2N2 (light/heat) —> N2 + CH2 (methylene)

toxic, explosive gas

methylene very reactive, leads to side products

Question 3

make Simmons-Smith reagent

Answer 3

CH2I2 + Zn(Cu) (ether) —> I-CH2-Zn-I-Cu complex

called organozinc/iodomethyl zinciodide

Question 4

Simmons-Smith mechanism

Answer 4

alkene + CH2I2Zn(Cu) complex (ether) —> 3 carbon ring (original alkene stereochemistry preserved) + ZnI2 + Cu

Question 5

alpha elimination

Answer 5

chloroform + KOH —> CCl3- + H20

a chlorine leaves on its own forming CCl2 (dicholoro carbene)