36-notes.pdf

8/14/2019 36-notes.pdf

1/28

Announcements:

Third Online Assessment is cancelled

Office Hours this week:Friday 4-5 pm (PP 104)

(or by appointment)

8/14/2019 36-notes.pdf

2/28

7. Green Inorganic Chemistry

Chem 281

Dr. Audrey H Moores

8/14/2019 36-notes.pdf

3/28

3

What is Mercury?

What on earth is Mercury?Its YOUR way to express yourself!

Please fill the questionnaire before April 16th.

8/14/2019 36-notes.pdf

4/28

!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

8/14/2019 36-notes.pdf

5/28

8/14/2019 36-notes.pdf

6/28

!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

8/14/2019 36-notes.pdf

7/28


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

8/14/2019 36-notes.pdf

8/28


! 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

8/14/2019 36-notes.pdf

9/28


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

8/14/2019 36-notes.pdf

10/28


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

8/14/2019 36-notes.pdf

11/28

! 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



SILICACHEMISTRY

8/14/2019 36-notes.pdf

12/28

! 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



SILICACHEMISTRY

8/14/2019 36-notes.pdf

13/28

! 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



SILICACHEMISTRY

8/14/2019 36-notes.pdf

14/28


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

8/14/2019 36-notes.pdf

15/28


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

8/14/2019 36-notes.pdf

16/28

! SiO2 is the major form of silicon! Glass chemistry

! Hydrophilicity of glass! Fabrication of hydrophobic glass


Hydrophilic Hydrophobic

SILICACHEMISTRY

8/14/2019 36-notes.pdf

17/28


! SiO2 in diatoms algeas! Diatomeous earth, fossilised

diatoms, are used for filtration

(celite)

SILICAINNATURE

8/14/2019 36-notes.pdf

18/28


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

8/14/2019 36-notes.pdf

19/28


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

8/14/2019 36-notes.pdf

20/28

8/14/2019 36-notes.pdf

21/28


! Mesoporous structures - array of pores with sizesbetween 1 and 10 nm

! Used in catalysis, sensing

SILICACHEMISTRY

8/14/2019 36-notes.pdf

22/28


! 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

8/14/2019 36-notes.pdf

23/28

! Organic compounds containing Si-C bonds! Si-C polarized towards C! Si mostly tetravalent, tetrahedral

23

ORGANOSILICONCOMPOUNDS

Poly(dimethylsiloxane)PDMS

Brook SilenesAdrian Brook - UofT

Silole

8/14/2019 36-notes.pdf

24/28

24

! SiliconesORGANOSILICONCOMPOUNDS

! Reactivity of Si-Cl! reactive bond, forms Si-OH with water

vs.

8/14/2019 36-notes.pdf

25/28

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

8/14/2019 36-notes.pdf

26/28

!Alcohol Protection! In organic transformations, it is desirable to

protect alcohols - preventing their reactivity as

proton provider.

! Deprotection: acid catalysed methanolysis


SILICONINORGANICSYNTHESIS

8/14/2019 36-notes.pdf

27/28

!Applications of silicon in organic chemistry! For further reading:


SILICONINORGANICSYNTHESIS

8/14/2019 36-notes.pdf

28/28

28

36-notes.pdf

Documents