Inorganic chemistry Unit-19 Metal Cluster.pdfkoreanhitz70
It's the best notes on the metal cluster of the subject inorganic chemistry. It presents knowledge on borane, diborane, carboranes, their reactions, introduction and classes.
Inorganic chemistry Unit-19 Metal Cluster.pdfkoreanhitz70
It's the best notes on the metal cluster of the subject inorganic chemistry. It presents knowledge on borane, diborane, carboranes, their reactions, introduction and classes.
Hybridization describes the bonding atoms from an atom's point of view. For a tetrahedral coordinated carbon (e.g. methane CH4), the carbon should have 4 orbitals with the correct symmetry to bond to the 4 hydrogen atoms.
Basic principles in organic chemistry --exercise with solutionssuresh gdvm
Basic principles in organic chemistry. basics of organic chemistry, types of organic compounds, effects in organic compounds such as inductive effect, electromeric effect, resonance, hyperconjugation, IUPAC nomenclature
Aldehydes and ketones contain the carbonyl group. Aldehydes are considered the most important functional group. Ketones A carbon double bonded to an oxygen is called a carbonyl group. Compounds in which the carbon of a carbonyl group is bonded to two other carbons
It is about molecular orbital theory specially mo diagram of diatomic atoms,their bond orders,bond lengths and stability and experimental evidences of ionisation energy from PES.
NOMENCLATURE OF ORGANIC COMPOUNDS BY -- KHUSH AHUJAKhushAhuja
In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended[1] by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry (informally called the Blue Book). Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry.
To avoid long and tedious names in normal communication, the official IUPAC naming recommendations are not always followed in practice, except when it is necessary to give an unambiguous and absolute definition to a compound. IUPAC names can sometimes be simpler than older names, as with ethanol, instead of ethyl alcohol. For relatively simple molecules they can be more easily understood than non-systematic names, which must be learnt or looked over. However, the common or trivial name is often substantially shorter and clearer, and so preferred. These non-systematic names are often derived from an original source of the compound. In addition, very long names may be less clear than structural formula.
Hybridization describes the bonding atoms from an atom's point of view. For a tetrahedral coordinated carbon (e.g. methane CH4), the carbon should have 4 orbitals with the correct symmetry to bond to the 4 hydrogen atoms.
Basic principles in organic chemistry --exercise with solutionssuresh gdvm
Basic principles in organic chemistry. basics of organic chemistry, types of organic compounds, effects in organic compounds such as inductive effect, electromeric effect, resonance, hyperconjugation, IUPAC nomenclature
Aldehydes and ketones contain the carbonyl group. Aldehydes are considered the most important functional group. Ketones A carbon double bonded to an oxygen is called a carbonyl group. Compounds in which the carbon of a carbonyl group is bonded to two other carbons
It is about molecular orbital theory specially mo diagram of diatomic atoms,their bond orders,bond lengths and stability and experimental evidences of ionisation energy from PES.
NOMENCLATURE OF ORGANIC COMPOUNDS BY -- KHUSH AHUJAKhushAhuja
In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended[1] by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry (informally called the Blue Book). Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry.
To avoid long and tedious names in normal communication, the official IUPAC naming recommendations are not always followed in practice, except when it is necessary to give an unambiguous and absolute definition to a compound. IUPAC names can sometimes be simpler than older names, as with ethanol, instead of ethyl alcohol. For relatively simple molecules they can be more easily understood than non-systematic names, which must be learnt or looked over. However, the common or trivial name is often substantially shorter and clearer, and so preferred. These non-systematic names are often derived from an original source of the compound. In addition, very long names may be less clear than structural formula.
Benzene is an organic chemical compound with the molecular formula C6H6. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point
5 Production Methods of Benzene cyclic hydrocarbon first isolated by Faraday a natural component of crude oil can be produced using different methods Pyrolysis gasoline, coal tar, Catalytic Reforming, Toluene hydrodealkylation, Toluene disproportionation
To study the properties, nomenclature and the physical as well chemical reactions of aliphatic and alkyl benzene. Might as well as the usage of benzene in our daily life routine
Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma around petrol (gasoline) stations.
It is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced annually.
Although a major industrial chemical, benzene finds limited use in consumer items because of its toxicity
In chemistry, aromaticity is a property of cyclic (ring-shaped), planar (flat) structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to other geometric or connective arrangements with the same set of atoms. Aromatic rings are very stable and do not break apart easily. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, but only aromatic rings have enhanced stability.
Organic chemistry has two main divisions. One division deals with aliphatic (fatty) compounds, the first compounds you encountered in Organic Chemistry I. The second division includes the aromatic (fragrant) compounds, of which benzene is a typical example.
Benzene and its derivatives- According to PCI Syllabus Ganesh Mote
Benzene history, nomenclature, orbital structure, resonance structure, kekule structure,synthetic evidences, structural and analytical evidences, Directive effect of benzene, structure and uses of DDT, BHC, saccharine
1. Introduction
2. History of benzene
3. Nomenclature
4. Orbital structure
5. Kekule structure
6. Resonance structure
7. Resonance energy and stability 8. Structural evidence
9. Synthetic evidence
10. Analytical evidence
11. Aromaticity and huckle rule
12. Method of preparation of benzene
13. Electrophilic substitution of benzene
14. Classification of substituent 15. Directive effect : Ortho and para director, meta director
16. Reaction of monosubstituted benzene
17. Effect of Substituents on reactivity and orientation of monosubstituted benzene towards electrophilic substitution 18. Structure and uses of BHC,DDT, Saccharine and chloramine
Using molecular orbital theory to explain bonding in cyclopropaneDaniel Morton
Following its discovery in 1881 by August Freund cyclopropane fueled the debate of how atoms interact within a molecule. Any bonding model used needed to fit with the following physical properties of cyclopropane.
Contributed by: Travis Kienholz (Undergraduate), University of Utah, 2015
1. The story of benzene
Write the electron configuration of Carbon. How many electrons are there in
Write the electron configuration of Carbon. How many electrons are there in
its outer shell? How many covalent bonds should carbon form?
its outer shell? How many covalent bonds should carbon form?
2. A new hydrocarbon isolated by Michael Faraday in 1825
Carbon = 92% Carbon (Atomic mass = 12)
Hydrogen = ? % (Atomic mass = 1)
Relative molecular mass = 78.
Calculate the empirical formula then the molecular formula
C H Molecular formula
% 92 100-92 = 8
Known RMM / RMM of
% divided by RAM 92 / 12 = 7.67 8/1=8 empirical formula
Divide by smallest 7.67 / 7.67 = 1 8 / 7.67 = 1.04 78 / (12 + 1) = 6
Ratio 1 1
The empirical formula is CH and the molecular formula is C 6H66suggesting that the
The empirical formula is CH and the molecular formula is C 6H suggesting that the
molecule contained aalarge number of double bonds.
molecule contained large number of double bonds.
3. 2 minute challenge: Draw as many possible structures for a hydrocarbon
with the formula C6H6 Make sure the structures satisfy the requirements of 4
bonds per carbon and 1 bond per hydrogen!
In 1865 after a dream about a snake biting its own tale, Kekulé suggested the
following structure for benzene.
Does this structure meet all the requirements of benzene?
4. Problem 1: Lack of reactivity of benzene
Chemists at the time were convinced that benzene (like other alkenes) should react
with bromine in the dark at room temperature.
Bromine water (brown) + alkene → Bromoalkane solution (colourless)
Observation: This did NOT happen with benzene.
Conclusion: Benzene is not a normal alkene
5. Problem 2: Thermodynamic stability of benzene
Enthalpy of hydrogenation (addition of hydrogen) to cyclohexene
was found to be -119kJmol-1
Predict the enthalpy of hydrogenation of benzene
Predict the enthalpy of hydrogenation of benzene
6. Theory verses experiment
Since three double bonds are present in benzene, then the comparable reaction
should liberate 3 times the energy of cyclohexene
= -(3 × 119) = - 357 kJ mol-1
Experimentally determined value for the hydrogenation of benzene
ΔH (hydrogenation) = -208kJ mol-1
Is Benzene more or less stable than expected?
Benzene is (360-208) = 149 kJ mol-1 more stable than otherwise expected, or if it
contained 3 ordinary C=C bonds.
7. E
Benzene
(predicted value)
Difference = 149kJ/mol
-357kJ/mol (3
Benzene (actual value) X –120)
Structure ???
Cyclohexane
-208kJ/mol
progress
8. Problem 3: Bond lengths of benzene
Bond Lengths /nm
C-C cyclohexane 0.154
C=C cyclohexane 0.134
•Compare the length of a single bond to a double bond
•Draw what benzene would look like if the different length double and
single bonds are alternating to form a 6 member ring.
Clue: Its not a perfect hexagon
9. What benzene would look like if it had fixed
alternating double-single bonds…
Different bond lengths in
benzene would cause
distortion
Q. Who is this celebrity?
A. Simon Cowell
10. Direct evidence
1981 an atomic surface probing technique was developed called Scanning
Tunneling Microscopy (STM). The first published STM image showed benzene
with an undistorted hexagonal shape.
www.newton.ex.ac.uk
11. All the bonds in benzene have the same length...
Bond Lengths /nm
C-C cyclohexane 0.154
C=C cyclohexane 0.134
C-C in benzene 0.140
•How does the carbon-carbon bond length of benzene compare to
double and single carbon-carbon bonds?
1. All bonds are of equal length
2. The bond length is between a double bond and a single bond.
• What do these two facts suggest about the structure of benzene?
12. The double-single bonds can’t be fixed in position!
Resonance suggests the two structures rapidly alternate between the two forms.
The resonance explanation suggests that Benzene is in such rapid equilibrium
between the two forms; we detect a ‘blurred’ combination of the two forms.
The electrons from the double bonds are therefore drawn as a circle shared
equally between the carbon atoms.
13. Current theory:
•Some text books still use the word “resonance” to describe the structure of
benzene.
•There is NO evidence to support two rapidly changing forms of benzene.
•Modern organic chemists use the word “conjugation” to describe how the
electrons are delocalized (spread) across the whole molecule…
Valence bond theory explains the
bonding in benzene as a series of
unhybridized p-orbitals which overlap
forming a cloud of electron density above
and below the molecule.
The spreading of electrons STABILIZES the molecule.
14. Drawing benzene
Which drawing most accurately represents
the structure and bonding in Benzene?
Explain
Are any of the pictures completely
incorrect? (i.e. not Benzene) if so which
and why?
Which representation takes longest to
draw? Which is quickest to draw?
In your opinion which picture is best
overall? Why?
•D is incorrect (cyclohexane not benzene!)
•A doesn’t show delocalized electrons and is time consuming to draw
•Organic chemists tend to use B or C if they want to draw mechanisms
15. Questions
1.Describe the 3 problems that scientists faced when trying to explain the
structure and bonding in Benzene.
2.What is the current understanding of the structure and bonding of Benzene?
(answer as if you were talking to a chemist who had never heard of Benzene)
3.How does this current knowledge Q2 better explain the problems you
mentioned in Q1?
4.“We now fully understand benzene” Do you agree or disagree with this claim?
Explain your answer.
5.What is the role of theory and experimentation in the advance of scientific
knowledge? Use the story of benzene to support your answer.
