Alkynes

Group Members

Novella I.C (20)

Nurul Izzatil A. (21)

R. Dandy Y. (22)

Raka S.W.S (23)

Reyan P.B. (24)

Rizqi Cahyo .Y (25)

Rosita Devi (26)

Sabrina Amelia J. (27)

Zaynita A . A (28)

X-1

Alkynes

Alkynes are aliphatic hydrocarbons (straight chain), unsaturated hydrocarbon with a triple bond between two carbon atoms.

Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature.

Like other hydrocarbons, alkynes are generally hydrophobic but tend to be more reactive. It is widely thought to be the greatest of all the functional groups.

Common Formula of Alkynes

CnH2n-2

n : Number of C

Function of Common Formula of Alkynes

• Determine the molecular formula alkynes compounds.

• The molecular structure of these compounds can be described by the molecular formula.

Example :Number of Carbons: 3Index Numbers of Hydrogen : 2(3)-2 = 6-2 = 4Molecular Formula: C3H4

Number of Carbons: 5Index Numbers of Hydrogens: 2(5)-2 = 10-2 = 8Molecular Formula: C5H8

Number of Carbons: 7Index Numbers of Hydrogen: 2(7)-2 = 14-2 = 12Molecular Formula: C7H12

Number of Carbons: 9Index Numbers of Hydrogen: 2(9)-2 = 18-2 = 16Molecular Formula: C9H16

http://chemistry.about.com/od/lecturenoteslabs/tp/Simple-Alkyne-Chains.htm

Nomenclature of

Alkynes

Straight Chain

1. Check the type of bond, if it has a triplicate bond, meaning the compound is an alkyne compound.

2. Count the number of its C atom.3. Write the prefix based on the number

of its C atom and ending with the suffix-una.4. If the number of C atoms alkyne compounds of

more than 3, give the number of each atom in such a way that the smallest number is located on the C atom attached to a triple bond. Then, naming compounds is initiated by the first C atom numbers are bound to triplicate bonds, followed by a dash (-) and the name of the main chain.

http://smartchemistry.wordpress.com/2012/02/14/tata-nama-senyawa-alkuna/

Example

2 - Pentyne

Butyne

Branched Chain1. Check the type of bond, if it has a triplicate

bond, meaning the compound is an alkyne compound.2. Determine the main chain and branch chain. The

main chain is determined from the longest chain of C atoms containing a triplicate bond.

3. Give the number of each atom in such a way that the smallest number is located on the C atom attached to a triplicate bond.

4. The main chain are named by the rules straight chain alkyne compound naming.

5. Branched chain named after the number of C atoms and the structure of the alkyl group.

6. Order in a compound name with a sequence of writing the name of the compound alkanes and alkenes.

http://smartchemistry.wordpress.com/2012/02/14/tata-nama-senyawa-alkuna/

Example

3-methyle-1-butyne (true) 2-methyle-3-butyne (false)

2,2-dimethyle-3-heptyne

Although the determination is wrong because the one of the main chain has the

longest chain, but doesn't through the triplicate.

http://www.chem-is-try.org/materi_kimia/kimia_organik_dasar/hidro-karbon/alkuna/

Determining of the main chain is true(Name: 3,5-dimethyle-3-prophyle-1-hexyne

Triplicate bond More than One

1. Check the type of bond, if it has a triple bond, meaning the compound is an alkyne compound.

2. Count the number of its C atom.3. Count the number of triplicate bond.4. If the number of all triplicate bonds = 2, compound

names end with the suffix-diuna. If the number of all triplicate bonds = 3, compound names end with the suffix-triuna.

5. Give the number of each atom in such a way that the smallest number is located in two or three C atoms bound to the first triplicate bond. Then, naming compounds C atom numbers preceded by the first and second / third that bound to the triplicate bond, followed by a dash (-) and the name of the main chain.

6. If there is a branched-chain, branched chain names similar to the naming of alkyne compounds.

1,3-Pentadiyne

Physical and Chemical

Properties of Alkyne

Physical Properties of Alkyne

• Alkyne is non-polar, have intermolecular forces are weak and have a molecular masssimilar to alkanes and alkenes.

• The higher interest alkyne, the greater the boiling point.

• At room temperature, the first three tribes are gaseous, the next rates are liquid, while the greater rates are in solid shape

Some physical properties of the alkyneNama alkuna

Molecularformula

Mr

Melting point(oC)

Boiling point(0 C)

Density(g/Cm3 )

On phase250 C

Etyne C2H2 26 -81 -85-

Gas

Propyne C3H4 40 -103 -23 - Gas

But-1-yne C4H6 54 -126 8 - Gas

Pen-1-yne C5H8 68 -90 40 0,690 Cair

Hex-1-yne C6H10 82 -132 71 0,716 Cair

Hept-1-yne C7H12 96 -81 100 0,733 Cair

Okt-1-yne C8H14 110 -79 126 0,740 Cair

Non-1-yne C9H16 124 -50 151 0,766 Cair

Dec-1-yne C10H18 138 -44 174 0,765 Cair

Chemical Properties of Alkyne

• With the same amount of C, the alkyne is more reactive than alkanes

• The existence of a triple bond which is owned alkyne allow the addition reactions, polymerization, substitution and combustion

A. Addition reaction of alkynes

In contrast to alkenes, alkynes have triple bonds so the adition reaction can take place in two stages

Example

Alkyne adition with the halogen

• Alkyne adition to the halide acid

Markovnikov  law applicable, H atoms of hydrogen halides into atoms Cdouble bind more H atoms.

B. Polymerization reaction of alkynes

In the etyne addition polymerization reaction (C2H2), two molecules etyne combine to form one molecule vinyl etyne (C4H4)

C. Substitution reaction of alkynes

Substitution on the alkyne reaction involves the release of H atoms bound to the C C bond at the end of the chain of alkyne

2CH CH + 2Na      2CH C-Na + H2   CH C-CH3 + NaI

Etyne   natrium asetilide            propyne

D. Combustion reaction of alkynes

Combustion alkyne with a limited amount of O2, CO or C will result in

2C2H2(g)  +  5O2(g)               4CO2(g)  +  2H2O(g)

Alkyne Isomers

Alkyne Isomers

Type of the alkyne isomers i structure isomers, namely framework/chain isomers and position isomers. Isomers of alkyne is started from alkyne butyne.

Examples of C5H8 isomers :

• Chain isomers

Pen-1-yne 3-methyl but-1-yne

• Position isomers

Pen-1-yne Pen-2-yne

• Alkyne also get isomers with cycloalkene that called functional group isomers

• C4H6 Functional group isomers

CH CH2 CH

CH CH2 CH CH CH3

Cyclobutene 3-methyl cyclopropene

CH C CH2 CH3

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