Alkanes Flashcards
What’s syn addition ?
If during addition reaction of an alkene the groups are attached on the same side it’s called syn addition.
What’s anti addition ?
If during addition reaction the groups are attached on the opposite direction then the addition is called anti addition.
In case of catalytic addition of H2 what kind of addition takes place ?
Syn addition
If the Alkane is unsymmetrical , then it forms what kind of mixture in addition ?
Racemic mixture , irrespective of syn or anti.
What does Red phosphorous and HI do when they act as catalyst to alchols and compounds containing C=O ?
Red phosphorus and HI reduces them to Alkane
With 1 degree halide , LiAlH4 reacts with which mechanism to form Alkane? What about NaBH4?
With 1 degree halide , LiAlH4 reacts in SN2 mechanism to form Alkane and NaBH4 does not undergo any reaction.
With 2 degree alkyl halide , LiAlH4 reacts with which mechanism to form Alkane? What about NaBH4?
LiAlH4 undergoes SN2 mechanism whereas NaBH4 undergoes SN1 mechanism through carbocation formation of hallide.
With 3 alkyl degree halide , LiAlH4 reacts with which mechanism to form Alkane? What about NaBH4?
LiBH4 will act as a base with 3 degree hallide through elimination reaction whereas NaBH4 will proceed through SN1 mechanism.
Catalytic Hydrogenation Reaction of Alkenes
CH3-CH=CH2–(H2,Pt/Pd/Ni)–> CH3-CH2-CH2.
Energy released during chemisorption is more than energy to break H-H bonds.
Sabatier Sandern’s reaction CnH2n—>?
CnH2n/CnH2n-2—H2,Ni/573K——->CnH2n+2
Alkane preparation by alkene reduction
(CH₃)₂-C=CH₂—Pd-C/C₂H₅OH—> (CH₃)₂CHCH₃
Alkane preparation by alkyl halide reduction
RX + H2–RA–>RH + HX
; X = Halogen
RA= Zn + CH3COOH/ Zn+ HCl
Wurtz Reaction for alkanes
2RI+Na–dry ether–>R-R+NaI
Alkane preparation by alkyl iodide reduction
RI+HI–Red Phosphorous/150 C–>RH-I2
Frankland Reaction ( Alkanes )
RI+Zn+RI—->RR+ZnI2
