Basics in Organic Reactions Mechanisms
In organic chemistry, the mechanism of an organic reaction is defined as a complete step-by-step explanation of how a reaction of organic compounds happens. A completely detailed mechanism would relate the first structure of the reactants with the last structure of the products and would represent changes in structure and energy all through the reaction step.
Heterolytic Bond Breaking
Heterolytic bond breaking is also known as heterolysis or heterolytic fission or ionic fission. It is defined as breaking of a covalent bond between two different atoms in which one atom gains both of the shared pair of electrons. The atom that gains both electrons is more electronegative than the other atom in covalent bond. The energy needed for heterolytic fission is called as heterolytic bond dissociation energy.
Polar Aprotic Solvent
Solvents that are chemically polar in nature and are not capable of hydrogen bonding (implying that a hydrogen atom directly linked with an electronegative atom is not found) are referred to as polar aprotic solvents. Some commonly used polar aprotic solvents are acetone, DMF, acetonitrile, DMSO, etc.
Oxygen Nucleophiles
Oxygen being an electron rich species with a lone pair electron, can act as a good nucleophile. Typically, oxygen nucleophiles can be found in these compounds- water, hydroxides and alcohols.
Carbon Nucleophiles
We are aware that carbon belongs to group IV and hence does not possess any lone pair of electrons. Implying that neutral carbon is not a nucleophile then how is carbon going to be nucleophilic? The answer to this is that when a carbon atom is attached to a metal (can be seen in the case of organometallic compounds), the metal atom develops a partial positive charge and carbon develops a partial negative charge, hence making carbon nucleophilic.
![Identify the reagent needed to accomplish the transformation below (enter the appropriate code from the reagent list)
H.
Ph Reagent]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbc96294a-6867-4c53-8945-7b1c26d22cf9%2Ffc13f4f6-3403-4b3b-8f79-9a79c60b233f%2Ff28whz_processed.jpeg&w=3840&q=75)
![Alkyl Halides (X = CI, Br or I): Assume AICI, is present if needed
2 of 2
G
un acid catalyst [H+], or pyridine, is present if needed.
он
OH
OH
CHJOH
AA
BB
DD
EE
FF
GG
HH
Ketones, Aldehydes and Epoxides: Assume "then H,0" is included if a protonation step is needed
K.
P
R
V
Acid Chlorides: Assume AICI, or pyridine is present if needed
YY
zZ
Other Reagents:
11 PCC in CH2C2
21 Br2, FeBr3
22 Mg. Et,0
23 Cl2, AICI3
24 SOCI2, pyridine
25 HNO3, H2SO4
26 fuming H2SO4
1 H3O* (dilute H2SO4) or H3O*, heat
2 conc. H2SO4, heat
3 NaOEt
12 NazCr207, H2S04, H2O
13 BH3•THF or 9-BBN, then H2O2, NaOH
14 Hg(OAc)2, H2O, then NaBH4
15 O3, then Zn, HCI or DMS
16 MCPBA or CH;CO3H
17 Br2, light or NBS, heat
4 t-BUOK
5 H2, Pt
6 H2, Lindlar's catalyst
7 Na, NH3
8 LAH or xs LAH, then H20
9 NABH4, CH3OH
10 NABH,CN, pH 5
27 Fe, HCI; then NaOH
28 Zn(Hg). НCI
29 KCN, or KCN + HCN
30 CO2, then H30*
18 HBr
19 HBr, ROOR
20 PB13
31 (H*]. HOʻ
32 NH3 (1 or 2 equiv.)
33 CH,NH2 (1 or 2 equiv)
34 (CH3)½NH (1 or 2 equiv)
35 EINH2 (1 or 2 equiv)
36 PHCH,NH2 (1 or 2 equiv).
37 LDA, -78 °C
(-H20)
Grignard, Wittig and Gilman Reagents:
Assume "then H,0" is included if a protonation step is needed
MgBr
MeMgBr
EtMgBr
PhMgBr
G1
G2
G3
G4
CuLi
Me,Culi Et,Culi (PHCH2),CULI
38 NaH, 25 °C
39 LIAI(OR);H, then H20
40 DIBAH, then H2O
41 Br2. [H3O*]
42 Br2, NaOH
43 Pyridine
G5
G6
G7
G8
MePh,P=CH2 PhyP=CHCH3 PhyP=CHCO,Et PhyP=CHPH
W1
w2
W3
W4](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbc96294a-6867-4c53-8945-7b1c26d22cf9%2Ffc13f4f6-3403-4b3b-8f79-9a79c60b233f%2Fdw6ntno_processed.jpeg&w=3840&q=75)
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