Organic Mechanism
description
Transcript of Organic Mechanism
![Page 1: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/1.jpg)
Organic Mechanism
By: Duyen Vuong 12D
![Page 2: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/2.jpg)
Content • Organic Mechanism • Vinyl polymers• Low density poly(ethene), LDPE
–Free radical formation• High density poly(ethene), HDPE
–Ziegler- Natta catalyst
• Bibliography
![Page 3: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/3.jpg)
Organic mechanisms
• To manufacture of poly(ethene)
• used to make polymers from vinyl monomers
• Mostly covalent bonds
• 2 types: – LDPE– HDPE
![Page 4: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/4.jpg)
Vinyl polymers• from vinyl monomers
(contain double carbon- carbon bonding)
• largest family of polymers
• made from the monomer ethylene/ ethene
• form a long chain of many thousands of carbon atoms containing only single bonds between atoms
![Page 5: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/5.jpg)
Examples of Vinyl Polymers
• polypropylene
• Polystyrene
• poly(vinyl chloride)
• Polyisobutylene/ type of rubber
• poly(methyl methacrylate)
• polytetrafluoroethylene
![Page 6: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/6.jpg)
Objective C.9.1
• Describe the free- radical mechanism involved in the manufacture of low- density polyethene
![Page 7: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/7.jpg)
Low density poly(ethene)
• Carried out at very high pressures (1000-3000 atm)
• At temperature about 500K (227ºC)• Average polymer molecule contains between 4 x
10³ to 4 x 10^4 carbon atoms • With short branches • Has a density of about 0.92g cm^-3• Used mostly for packaging • Formed under free radical formation
![Page 8: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/8.jpg)
Free radical formation
• Definition- molecules with unpaired electrons • Highly reactive due to unpaired electrons• Biology example- PEROXIDATION (producing
ATP inside the body)• Elements example- oxygen (ROS- reactive
oxygen species) , transition metals (Cu- copper, can lose and gain electrons easily)
• Progress= initiate propagation termination
![Page 9: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/9.jpg)
Initiate • First step• Homolytic fission
– when a bond is broken, each of the bonded atoms or groups takes one of the bonding pair of electrons.
–
• Not heterolytic fission – when a bond is broken and two electrons go to one of
the element/compound
• Examples:– Cl2 (UV light) 2Cl·– Br2 2 Br·
![Page 10: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/10.jpg)
Propagation • Each step must have odd number of unshared electrons • Two compounds containing one unshared electron each
never, ever, ever combine • Unpaired electrons wanted will swipe one of themselves
to pair with • Leading us back to the beginning • adding of more and more monomer molecules to the
growing chains • Examples:
– Cl · + CH4 · CH3 + HCL– · CH3 + Cl2 CH3Cl + Cl ·– Cl · + CH4 -> · CH3 + HCL– · CH3 + Cl2 -> CH3Cl + Cl·
![Page 11: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/11.jpg)
Termination • Each of two unpaired compounds form
radical–radical combination (coupling) or a disproportionation
• Examples: – · Cl+ · Cl -> Cl2– · CH3+ · CL-> CH3Cl– · CH3+ · CH3->C2H6
![Page 12: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/12.jpg)
Examples of the free radical formation
![Page 13: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/13.jpg)
![Page 14: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/14.jpg)
![Page 15: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/15.jpg)
OR
![Page 16: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/16.jpg)
![Page 17: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/17.jpg)
Objectives C.9.2
• Outline the use of Ziegler- Natta catalyst in the manufacture of high- density polyethene
![Page 18: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/18.jpg)
High density poly(ethene)
• Carried out at pressures (1-50 atm)• At low temperature about 350K (77ºC)• Using Zieler- Natta catalyst • Maily of linear chains with very little
branching• Higher density 0.96 g cm^-3• More rigid structure• Used to make containers and pipes
![Page 19: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/19.jpg)
Ziegler- Natta catalyst
method of vinyl polymerization• discovered by two scientists: Ziegler and Natta
in the 1950s • Can’t make some other kinds of monomers,
such as poly(vinyl chloride)• Suspension of titanium (III) or titanium (IV)
chloride together with an Alkyl- aluminum compound
• Catalyst and co catalyst:– TiCl3 and Al(C2H5)2Cl – TiCl4 with Al(C2H5)3
![Page 20: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/20.jpg)
Industry process
![Page 21: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/21.jpg)
Chemical process
• TiCl3 can arrange itself into a number of crystal structures
• each titanium atom is coordinated to six chlorine atoms= octahedral geometry
![Page 22: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/22.jpg)
• Ti-
– transition metal
– Have six empty orbitals (4s and five 3d-orbitals )
• Needs 2 electrons to fill up the orbital
• Filled 1 up by Al(C2H5)2Cl
![Page 23: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/23.jpg)
• Combine with vinyl monomer like propylene nth(C3H6)
• two electrons in the π-system of a carbon-carbon double bond fill the left over empty orbital
• Form a complex
![Page 24: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/24.jpg)
• Several pair of electrons shift position
• The propylene monomer migrates
![Page 25: Organic Mechanism](https://reader036.fdocuments.us/reader036/viewer/2022062304/5681444d550346895db0ea2b/html5/thumbnails/25.jpg)
Bibliography• http://www.stopagingnow.com/images/free_radical.jpg• http://img125.imageshack.us/img125/4794/background1qa5.jpg• http://media.photobucket.com/image/background/tatcalaquakhu/Backgrounds10.jpg• http://www.exrx.net/Nutrition/Antioxidants/Introduction.html• http://www.answers.com/topic/monomer• http://69.90.174.246/photos/display_pic_with_logo/90327/90327,1220853365,8.jpg• http://www.adobetutorialz.com/content_images/AdobePhotoshop/ART-D/tutorial402/cool-abstract
-background.jpg• http://www.thegioiwallpaper.com/wallpaper/Background-15/• http://www.ucc.ie/ucc/depts/biochemistry/students/Images/science_background.jpg• http://www.uku.fi/~poso/thc_reseptorissa.jpg.jpg• http://buzzert.zanneth.com/images/wallpaper/Liquid%20Plasma.jpg• http://www.economicexpert.com/a/Ziegler:Natta:catalyst.htm• http://www.exrx.net/Nutrition/Antioxidants/Introduction.html• http://chemistry2.csudh.edu/rpendarvis/Radicals.html• http://www.chem.uky.edu/courses/che230/RBG/handouts/freeradchainrules.html• http://www.sciencecollege.co.uk/SC/reaction_mechanisms/freeradical.jpg• http://www.steve.gb.com/images/molecules/halogen_compounds/chloromethane_
%28free_radical_mechanism%29.png• http://pslc.ws/mactest/ziegler.htm• http://media-2.web.britannica.com/eb-media/60/1660-004-390F09C4.gif• http://pslc.ws/mactest/radical.htm