Alkynes презентация

Alkynes Group memers: Garapov arman Dobrednev gleb Zhumabayev yernur Orazbaev anuar Toyghambaev akzhol

Alkynes(or acetylenes) Hydrocarbons that  contain the carboncarbon triple bond  –C (triple)C- are called  alkynes General formula: CnH2n-2 (n>1) Alkynes are named by using the –yne suffix in place of the –ane suffix of alkanes.  Each triple bond  contains one sigma (σ)  and two pi (π) bonds.   Because of the π bonds in  their structure alkynes  are unsaturated  hydrocarbons. 

NOMENCLATURE The naming of alkynes is similar to that of other hydrocarbons. Alkynes may contain more than one triple bond. Alkenynes

CYCLOALKYNES Alkynes may be cyclo compounds (cycloalkynes). The simplest stable cycloalkyne at room temperature is cyclononyne.

ISOMERISM The triple bond may be in different locations in an alkyne, so alkynes can exhibit structural isomerism. For the first two members of alkynes there is only one possible position for bond, so for these cases there is no isomerism. Alkynes, alkadienes and cycloalkenes containing the same number of carbon atoms are isomers of each other.

PHYSICAL PROPERTIES Similar to alkanes, alkenes : Insoluble in water. BUT  Soluble in organic solvents Density less than water 

CHEMICAL PROPERTIES Alkynes are unsaturated compounds and their chemical properties are similar to alkenes. Alkynes undergo combustion reactions and addition reactions, as alkenes do. In addition, alkynes undergo substitution reactions with metals.

COMBUSTION REACTIONS Alkynes produce CO2 and H20 when they're burnt with a sufficient amount of oxigen. The general combustion reaction is:

 ADDITION REACTIONS Addition reactions occur by breaking the π bonds of the triple bond. Hydrogen, halogens, hydrogen halides and water may give addition reactions with alkynes. ADDITION OF HYDROGEN :       Two hydrogen molecules are added to one triple bond using a nickel, platinum or palladium catalyst. Alkenes are the intermediate products. 

PREPERATION OF ALKYNES Alkynes can be synthesized from metallic acetlylides and alkyl halides.

ACETYLENE Acetylene, the first member of the alkyne series, is one of the major chemicals used in industry. Physical properties: Very light odor Colorless Soluble in water Soluble in acetone Boiling point -83* C Can be liquified at 1*C Chemical properties: It burns with a bright flame Explodes at about 15 atm pressure

ALKYNYL GROUP Alkynyl groups are formed from alkynes by removing one H atom. The most common alkynyl groups are ethynyl, 1–propynyl, and 1–butynyl

USES OF ALKYNES Histrionicotoxin toxic alkyne present in South American frogs used to make poison-tipped arrows Ichthyothereol highly toxic alkyne found in the leaves of a Brazilian herb used to kill fish Calicheamicin and Esperamicin extremely toxic to cells breaks double strand of DNA researchers are trying to use it to develop a cancer fighting drug Capillin natural plant fungicide