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Announcements:
Third Online Assessment is cancelled
Office Hours this week:Friday 4-5 pm (PP 104)
(or by appointment)
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7. Green Inorganic Chemistry
Chem 281
Dr. Audrey H Moores
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What is Mercury?
What on earth is Mercury?Its YOUR way to express yourself!
Please fill the questionnaire before April 16th.
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!Applicable to science popularisation! Reagents: what the company buys and puts in
the process
! Products: what the company sells, what we buy! The rest: catalysts, additives, solvents, energy! Synthetic strategy
ReagentsProducts
Catalysts
Additives
Solvents
Energy
5 Key elements of a chemical
process
I. Green Chemistry: introduction and definitionsFrom Last Class
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!Silicon: ID
! Silicon is the second most abundant element of the earthcrust. It is mostly present in the form of silicates (n cation m+,SiO4
-), e.g (Fe,Mg)2SiO4: olivine
! 29 Si NMR NMR active (spin of !), routinely used especially for silica containing materials
CHEM 281: Main group chemistry Silicon chemistry
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
I II XIII XIV XV XVI XVII XVIII
H Ne
Li Be B C N O F Ar
Na Mg Al Si P S Cl Kr
K Ca Ga Ge As Se Br Xe
" Silicon is more electropositiveand biggerthan C" Silicon is mostly tetravalentlike C
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
! SiO2 is the major form of silicon! Quartz: crystalline form of SiO2! Sand is mostly composed of small pieces
of quartz
http://www.espaceterreetmateriaux.be/verre_et_cristal.htm
Hexagonal prismaticcrystal lattice
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
http://www.espaceterreetmateriaux.be/verre_et_cristal.htm
Def: Glass:
Non crystallinematerial (glassy phase)
Non crystalline silica(glass panel)
! SiO2 is the major form of silicon! Glass chemistry
! Pure silica "glass melting point: 2300 C! Soda-lime glass: 1500 C (+ Na2CO3)
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
http://en.wikipedia.org/wiki/Float_glass
Corning Museum of Glass (Corning NY, USA)
! Float Glass Production! Raw materials melted (sand, Na2CO3, and additives) - 1500 C! Viscous liquid poured onto a molten tin bath
! bath about 3-4 m wide, 50 m long, 6cm deep! Glass is slid on the tin bath and goes through a gradient of temperature
(from 1100 to 600 C)! Glass annealing to easy tension in glass
SILICACHEMISTRY
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! Tension in Glass! Coolingof glass creates tensions inside the glass matrix. These comes
from the inhomogeneity of the temperature in glass as it is cooling
! These tensions are visible using polarized light.! E.g. glass and plastic objects both show tensions
CHEM 281: Main group chemistry Silicon chemistry
Corning Museum of Glass (Corning NY, USA)
SILICACHEMISTRY
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! Tension in Glass! Cooling causes tensions inside the matrix
! when the glass breaks it does so in more pieces
! The same tensions causes a hardened surface! After any glass fabrication process (float glass process, glass blowing
process or molding): reheating (annealing) is performed to ease the
tensions and afford a more robust glass
CHEM 281: Main group chemistry Silicon chemistry
Corning Museum of Glass (Corning NY, USA)
SILICACHEMISTRY
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! Tempered Glass, Safety Glass! Tempered glass (St Gobain process)! Hot glass (between 500 and 700 C) are subjected to air jets at room
temperature: fast cooling. Tensions are trapped and the surface of glass
is contracted. These tensions create a tougher glass 2 to 5 times tougher
than ordinary glass), but also will make glass breaking into small piecewhen broken. These pieces will not cut the skin. Application: Public
phones, side windows of cars, bus, trains
CHEM 281: Main group chemistry Silicon chemistry
Corning Museum of Glass (Corning NY, USA)
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
Non temperedsafety glass
Ordinary glass
Temperedsafety glass
! Tempered Glass, Safety Glass! Safety glass! May be tempered glass too. It is made of pieces of glass trapping a layer
of polymer. Armored glass are made by multiple layers of this kind.
Application: one layer, car windshields; multiple layers, armored glass
for banks, armored cars, bullet proof vests
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
HF is hazardous: it candissolve your bones too!
! Functionalization of glass surface! Fluoride chemistry: how to dissolve glass
! Glass has good chemical resistance apart from HF, F-canattack Si centers and form very strong Si-F bonds
SILICACHEMISTRY
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! SiO2 is the major form of silicon! Glass chemistry
! Hydrophilicity of glass! Fabrication of hydrophobic glass
CHEM 281: Main group chemistry Silicon chemistry
Hydrophilic Hydrophobic
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
! SiO2 in diatoms algeas! Diatomeous earth, fossilised
diatoms, are used for filtration
(celite)
SILICAINNATURE
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CHEM 281: Main group chemistry Silicon chemistry
http://www.sciencedaily.com/releases/2012/03/120323094036.htm
! E.g. Sugar ribose sensing: The biosensor, described in a paperpublished this week in the scientific journal PLoS ONE,
includes fluorescent proteins embedded in a diatom shell that
alter their glow when they are exposed to a particularsubstance.
! Diatoms applications! Sensing! Catalysis! Remediation
SILICAINNATURE
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CHEM 281: Main group chemistry Silicon chemistry
Polymer precursor (Si(OEt)
4)
Solvent (EtOH/H2O) Soap = surfactant
! Mesoporous structures - array of pores with sizesbetween 1 and 10 nm
! Used in catalysis, sensing
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
! Mesoporous structures - array of pores with sizesbetween 1 and 10 nm
! Used in catalysis, sensing
SILICACHEMISTRY
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CHEM 281: Main group chemistry Silicon chemistry
! Semi conducting properties silicon is a key elementto the fabrication of transistors
! Silicon technology: highly pure monocrystalline Siwafers
! more on semi-conductors Friday with Dr. Sewall!
ELEMENTALSILICON
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! Organic compounds containing Si-C bonds! Si-C polarized towards C! Si mostly tetravalent, tetrahedral
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ORGANOSILICONCOMPOUNDS
Poly(dimethylsiloxane)PDMS
Brook SilenesAdrian Brook - UofT
Silole
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! SiliconesORGANOSILICONCOMPOUNDS
! Reactivity of Si-Cl! reactive bond, forms Si-OH with water
vs.
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CHEM 281: Main group chemistry silicon chemistry
! Silicon vs. Carbon! Berry pseudorotaion! Occurs because Si can be hypervalent!And bipyramidal structures are more flexible
Enantiomers of Si can not beconserved in the presence of
Lewis base solvents (water, THF)
ORGANOSILICONCOMPOUNDS
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!Alcohol Protection! In organic transformations, it is desirable to
protect alcohols - preventing their reactivity as
proton provider.
! Deprotection: acid catalysed methanolysis
CHEM 281: Main group chemistry silicon chemistry
SILICONINORGANICSYNTHESIS
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!Applications of silicon in organic chemistry! For further reading:
CHEM 281: Main group chemistry silicon chemistry
SILICONINORGANICSYNTHESIS
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