Chemistry > Hydrocarbons > 12.0 Methods of Preparation Alkynes
Hydrocarbons
1.0 Introduction
2.0 Alkanes
3.0 Methods of Preparation Alkanes
4.0 Physical Proparties
5.0 Chemical Properties
6.0 Alkenes
7.0 Methods of Preparation Alkenes
7.1 Dehydrohalgoenation
7.2 Dehydration of Alcohols
7.3 Dehalogenation
7.4 Thermal elimination reaction
7.5 By partial reduction of alkynes:
7.6 Wittig Reaction
7.7 Kolbe hydrocarbon synthesis
8.0 Physical Proparties
9.0 Chemical Properties
10.0 Mechanism Of Some Important Reaction Of Alkenes
10.1 Mechanism of halogen addition
10.2 Mechanism of halohydrin formation
10.3 Syn - hydroxylation
10.4 Oxidation reactions of alkenes
11.0 Alkynes
12.0 Methods of Preparation Alkynes
12.1 Industrial source
12.2 Kolbe’s method
12.3 Dehydrohalogenation of 1, 2 – dihalides
12.4 Dehydrohalogenation of 1, 1 – dihalides
12.5 Dehalogenation of tetrahalides or trihalides
12.6 Alkylation of acetylene and terminal alkynes
13.0 Physical Properties
14.0 Chemical Properteis
14.1 Electrophilic addition reactions
14.2 Acidity of Alkynes
14.3 Aromatic Hydrocarbons
14.4 Structure of Benzene
15.0 Modern Concept
15.1 Aromaticity in Benzene and Related Systems
15.2 Huckel’s rule or $\left( {{\bf{4n}}{\text{ }} + {\text{ }}{\bf{2}}} \right)\pi $ electron rule
16.0 Properteis
17.0 Mechanism of Electrophilic Substitution Reactions
17.1 Nitration
17.2 Friedel – Craft Alkylation
17.3 Friedel – Craft Acylation
17.4 Reactions of side chains
18.0 Toluene
19.0 Alkenyl Benzene
12.6 Alkylation of acetylene and terminal alkynes
7.2 Dehydration of Alcohols
7.3 Dehalogenation
7.4 Thermal elimination reaction
7.5 By partial reduction of alkynes:
7.6 Wittig Reaction
7.7 Kolbe hydrocarbon synthesis
10.2 Mechanism of halohydrin formation
10.3 Syn - hydroxylation
10.4 Oxidation reactions of alkenes
12.2 Kolbe’s method
12.3 Dehydrohalogenation of 1, 2 – dihalides
12.4 Dehydrohalogenation of 1, 1 – dihalides
12.5 Dehalogenation of tetrahalides or trihalides
12.6 Alkylation of acetylene and terminal alkynes
14.2 Acidity of Alkynes
14.3 Aromatic Hydrocarbons
14.4 Structure of Benzene
15.2 Huckel’s rule or $\left( {{\bf{4n}}{\text{ }} + {\text{ }}{\bf{2}}} \right)\pi $ electron rule
17.2 Friedel – Craft Alkylation
17.3 Friedel – Craft Acylation
17.4 Reactions of side chains
i.e. an alkyne with $ - C \equiv CH$ at the end of chain. This method is used to prepare higher alkynes.
\[HC \equiv CH + Na\xrightarrow{{Liquid\,\,N{H_3}}}HC \equiv \mathop C\limits^ - \mathop {Na}\limits^ + \xrightarrow{{RX}}HC \equiv CR\]
\[RC \equiv CH + Na\xrightarrow{{Liquid\,\,N{H_3}}}RC \equiv \mathop C\limits^ - \mathop {Na}\limits^ + \xrightarrow{{R'X}}RC \equiv CR'\]
Terminal alkyne
\[C{H_3}C \equiv CH\xrightarrow[{(ii)\,\,C{H_3}C{H_2}I}]{{(i)\,\,Na/liq.\,\,N{H_3}}}C{H_3}C \equiv CC{H_2}C{H_3}(2 - pentyne)\]
Note:
RX and $R'X\,\,should\,\,be\,\,{1^o}$ alkyl halides, since higher secondary and tertiary halides give mainly alkenes when they react with sodium salt of alkynes.
Alkylation can also be done by using Grignard’s reagent.
\[HC \equiv C - Mg - Br + C{H_3}Br\xrightarrow{{}}CH \equiv CC{H_3} + MgB{r_2}\]
