I hope You all like it. I hope It is very beneficial for you all. I really thought that you all get enough knowledge from this presentation. This presentation is about materials and their classifications. After you read this presentation you knowledge is not as before.
I hope You all like it. I hope It is very beneficial for you all. I really thought that you all get enough knowledge from this presentation. This presentation is about materials and their classifications. After you read this presentation you knowledge is not as before.
I hope You all like it. I hope It is very beneficial for you all. I really thought that you all get enough knowledge from this presentation. This presentation is about materials and their classifications. After you read this presentation you knowledge is not as before.
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Benzilic acid rearrangement. The benzilic acid rearrangement is formally the 1,2-rearrangement of 1,2-diketones to form α-hydroxy–carboxylic acids using a base. This reaction receives its name from the reaction of benzil with potassium hydroxide to form benzilic acid.
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
Benzene has 6π electrons delocalized in 6p orbitals that overlap above and below the plane of the ring. Because benzene’s six pie electrons satisfy Huckel’s rule, benzene is especially stable. Reaction that keep the aromatic ring intact are therefore favoured
This is Power Point Presentation on Topic "Electrophilic Aromatic Substitution Reactions" as per syllabus of "University of Mumbai" for S.Y. B. Pharmacy (Sem.: IV) students.
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Benzilic acid rearrangement. The benzilic acid rearrangement is formally the 1,2-rearrangement of 1,2-diketones to form α-hydroxy–carboxylic acids using a base. This reaction receives its name from the reaction of benzil with potassium hydroxide to form benzilic acid.
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
Benzene has 6π electrons delocalized in 6p orbitals that overlap above and below the plane of the ring. Because benzene’s six pie electrons satisfy Huckel’s rule, benzene is especially stable. Reaction that keep the aromatic ring intact are therefore favoured
This is Power Point Presentation on Topic "Electrophilic Aromatic Substitution Reactions" as per syllabus of "University of Mumbai" for S.Y. B. Pharmacy (Sem.: IV) students.
Introduction to benzene, orbital picture, resonance in benzene, Huckel‟s rule
Reactions of benzene - nitration, sulphonation, halogenation- reactivity, Friedel- Craft‟s alkylation- reactivity, limitations, Friedel-Craft‟s acylation.
Substituents, effect of substituents on reactivity and orientation of mono substituted benzene compounds towards electrophilic substitution reaction.
Substitution Reactions of Benzene and Other Aroma.pdfajitdoll
Substitution Reactions of Benzene and Other Aromatic Compounds The
remarkable stability of the unsaturated hydrocarbon benzene has been discussed in an earlier
section. The chemical reactivity of benzene contrasts with that of the alkenes in that substitution
reactions occur in preference to addition reactions, as illustrated in the following diagram (some
comparable reactions of cyclohexene are shown in the green box). A demonstration of bromine
substitution and addition reactions is helpful at this point, and a virtual demonstration may be
initiated by clicking here. Many other substitution reactions of benzene have been observed, the
five most useful are listed below (chlorination and bromination are the most common
halogenation reactions). Since the reagents and conditions employed in these reactions are
electrophilic, these reactions are commonly referred to as Electrophilic Aromatic Substitution.
The catalysts and co-reagents serve to generate the strong electrophilic species needed to effect
the initial step of the substitution. The specific electrophile believed to function in each type of
reaction is listed in the right hand column. Reaction Type Typical Equation Electrophile E(+)
Halogenation: C6H6 + Cl2 & heat FeCl3 catalyst ——> C6H5Cl + HCl Chlorobenzene Cl(+) or
Br(+) Nitration: C6H6 + HNO3 & heat H2SO4 catalyst ——> C6H5NO2 + H2O Nitrobenzene
NO2(+) Sulfonation: C6H6 + H2SO4 + SO3 & heat ——> C6H5SO3H + H2O Benzenesulfonic
acid SO3H(+) Alkylation: Friedel-Crafts C6H6 + R-Cl & heat AlCl3 catalyst ——> C6H5-R +
HCl An Arene R(+) Acylation: Friedel-Crafts C6H6 + RCOCl & heat AlCl3 catalyst ——>
C6H5COR + HCl An Aryl Ketone RCO(+) 1. A Mechanism for Electrophilic Substitution
Reactions of Benzene A two-step mechanism has been proposed for these electrophilic
substitution reactions. In the first, slow or rate-determining, step the electrophile forms a sigma-
bond to the benzene ring, generating a positively charged benzenonium intermediate. In the
second, fast step, a proton is removed from this intermediate, yielding a substituted benzene ring.
The following four-part illustration shows this mechanism for the bromination reaction. Also, an
animated diagram may be viewed. Bromination of Benzene - An Example of Electrophilic
Aromatic Substitution There are four stages to this slide show. These may be viewed
repeatedly by continued clicking of the \"Next Slide\" button. To see an animated model of this
reaction using ball&stick models . This mechanism for electrophilic aromatic substitution
should be considered in context with other mechanisms involving carbocation intermediates.
These include SN1 and E1 reactions of alkyl halides, and Brønsted acid addition reactions of
alkenes. To summarize, when carbocation intermediates are formed one can expect them to react
further by one or more of the following modes: 1. The cation may bond to a nucleophile to give
a substitution or addition product. 2. The cation may transfer a proton to a base, g.
a complete description of the particle size distribution of particles in different categories. Sedimentation is a phenomenon that completely work with the size of particles.
A slide with a complete description of Belt and Conveyors. I hope after reading this presentation a reader can completely understand the mechanism of belts and conveyors.
Chemical reaction engineering is that engineering activity which is concerned with the exploitation of chemical reactions on commercial scale.
The areas of different fields of science like:
Oil Refining
Pharmaceuticals
Biotechnology
Chemical Industries
Sustainable Development
Chemical reaction engineering is that engineering activity which is concerned with the exploitation of chemical reactions on commercial scale.
The areas of different fields of science like:
Oil Refining
Pharmaceuticals
Biotechnology
Chemical Industries
Sustainable Development
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
Difference between batch,mixed flow & plug-flow reactorUsman Shah
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
This slide completely describes you about the stuff include in it and also everything about chemical engineering. Fluid Mechanics. Thermodynamics. Mass Transfer Chemical Engineering. Energy Engineering, Mass Transfer 2, Heat Transfer,
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
TOP 10 B TECH COLLEGES IN JAIPUR 2024.pptxnikitacareer3
Looking for the best engineering colleges in Jaipur for 2024?
Check out our list of the top 10 B.Tech colleges to help you make the right choice for your future career!
1) MNIT
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TO KNOW MORE ABOUT COLLEGES, FEES AND PLACEMENT, WATCH THE FULL VIDEO GIVEN BELOW ON "TOP 10 B TECH COLLEGES IN JAIPUR"
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VISIT CAREER MANTRA PORTAL TO KNOW MORE ABOUT COLLEGES/UNIVERSITITES in Jaipur:
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Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
1. 16. Chemistry of
Benzene: Electrophilic
Aromatic Substitution
Based on McMurry’s Organic Chemistry, 7th
edition
2. 2
Substitution Reactions of Benzene
and Its Derivatives
Benzene is aromatic: a cyclic conjugated
compound with 6 π electrons
Reactions of benzene lead to the retention of the
aromatic core
3. 3
Why this Chapter?
Continuation of coverage of aromatic compounds in
preceding chapter…focus shift to understanding
reactions
Examine relationship between aromatic structure
and reactivity
Relationship critical to understanding of how
biological molecules/pharmaceutical agents are
synthesized
4. 4
Electrophilic Aromatic Bromination
Benzene’s π electrons participate as a Lewis base in
reactions with Lewis acids
The product is formed by loss of a proton, which is replaced
by bromine
FeBr3 is added as a catalyst to polarize the bromine reagent
In the first step the π electrons act as a nucleophile toward Br2
(in a complex with FeBr3)
This forms a cationic addition intermediate from benzene and
a bromine cation
The intermediate is not aromatic and therefore high in energy
5. 5
Formation of Product from
Intermediate The cationic addition intermediate
transfers a proton to FeBr4
-
(from Br-
and
FeBr3)
This restores aromaticity (in contrast
with addition in alkenes)
6. 6
Other Aromatic Halogenations Chlorine and iodine (but not fluorine, which is too reactive)
can produce aromatic substitution with the addition of
other reagents to promote the reaction
Chlorination requires FeCl3
Iodine must be oxidized to form a more powerful I+
species
(with Cu2+
from CuCl2)
7. 7
Aromatic Nitration The combination of nitric acid and sulfuric acid produces NO2
+
(nitronium ion)
The reaction with benzene produces nitrobenzene
The Nitro group can be reduced to an Amino group if needed
8. 8
Aromatic Sulfonation Substitution of H by SO3 (sulfonation)
Reaction with a mixture of sulfuric acid and SO3 (“Fuming H2SO4)
Reactive species is sulfur trioxide or its conjugate acid
Sulfonamides are “sulfa drug” antibiotics
9. 9
Alkylation of Aromatic Rings: The Friedel–Crafts
Reaction
Alkylation among most
useful electrophilic
aromatic substitution
reactions
Aromatic substitution
of R+
for H+
Aluminum chloride
promotes the
formation of the
carbocation
10. 10
Limitations of the Friedel-Crafts Alkylation
Only alkyl halides can be used (F, Cl, I, Br)
Aryl halides and vinylic halides do not react (their
carbocations are too hard to form)
Will not work with rings containing an amino group
substituent or a strongly electron-withdrawing group
11. 11
Other Problems with Alkylation
Multiple alkylations can occur because the first alkylation is
activating
Carbocation Rearrangements Occur During Alkylation
Similar to those occuring during electrophilic additions to alkene
Can involve H or alkyl shifts
12. 12
Acylation of Aromatic Rings
Reaction of an acid chloride (RCOCl) and an aromatic ring
in the presence of AlCl3 introduces acyl group, COR
Benzene with acetyl chloride yields acetophenone
Avoids many of the problems of alkylation
Only substitutes once, because acyl group is deactivating
No rearrangement because of resonance stabilized cation
13. 13
Mechanism of Friedel-Crafts Acylation
Similar to alkylation
Reactive electrophile: resonance-stabilized acyl cation
An acyl cation does not rearrange
Can reduce carbonyl to get alkyl product
14. 14
Substituent Effects in Aromatic Rings
Substituents can cause a compound to be (much) more or
(much) less reactive than benzene
Substituents affect the orientation of the reaction – the
positional relationship is controlled
ortho- and para-directing activators, ortho- and para-
directing deactivators, and meta-directing
deactivators.
15. 15
Origins of Substituent Effects
An interplay of inductive effects and resonance effects
Inductive effect - withdrawal or donation of electrons
through a σ bond = Polar Covalent Bonds
Resonance effect - withdrawal or donation of electrons
through a π bond due to the overlap of a p orbital on the
substituent with a p orbital on the aromatic ring
16. 16
Inductive Effects
Controlled by electronegativity and the polarity of
bonds in functional groups
Halogens, C=O, CN, and NO2 withdraw electrons
through σ bond connected to ring
Alkyl groups donate electrons
17. 17
Resonance Effects – Electron Withdrawal
C=O, CN, NO2 substituents withdraw electrons from
the aromatic ring by resonance
π electrons flow from the rings to the substituents
Look for a double (or triple) bond connected to
the ring by a single bond
18. 18
Resonance Effects – Electron Donation
Halogen, OH, alkoxyl (OR), and amino substituents
donate electrons
π electrons flow from the substituents to the ring
Effect is greatest at ortho and para positions
Look for a lone pair on an atom attached to the ring
19. 19
An Explanation of Substituent Effects
Activating groups donate
electrons to the ring,
stabilizing the
carbocation intermediate
Deactivating groups
withdraw electrons from
the ring, destabilizing
carbocation intermediate
20. 20
Ortho/Para-Directing Activators: Alkyl Groups Alkyl groups activate by induction: direct further substitution
to positions ortho and para to themselves
Alkyl group has most effect on the ortho and para positions
21. 21
Ortho/Para-Directing Activators: OH and NH2
Alkoxyl, and amino groups have a strong, electron-
donating resonance effect
Most pronounced at the ortho and para positions
22. 22
Ortho/Para-Directing Deactivators: Halogens
Electron-withdrawing inductive effect outweighs weaker electron-
donating resonance effect
Resonance effect is only at the ortho and para positions,
stabilizing carbocation intermediate
23. 23
Meta-Directing Deactivators Inductive and resonance effects reinforce each other
Ortho and para intermediates destabilized by
deactivation of carbocation intermediate
Resonance cannot produce stabilization
25. 25
Trisubstituted Benzenes: Additivity of Effects
If the directing effects of the two groups are the same, the
result is additive
If the directing effects of two groups oppose each other, the
more powerful activating group decides the principal outcome
Usually gives mixtures of products
26. 26
Meta-Disubstituted Compounds
The reaction site is too hindered
To make aromatic rings with three adjacent
substituents, it is best to start with an ortho-
disubstituted compound
27. 27
Nucleophilic Aromatic Substitution Aryl halides with electron-withdrawing substituents ortho and para
react with nucleophiles (electron withdrawing needed to accept
electrons from the nucleophile)
Form addition intermediate (Meisenheimer complex) that is
stabilized by electron-withdrawal. Halide is leaving group.
28. 28
Benzyne: Substitution of Unactivated Aromatics
Phenol is prepared industrially by treatment of chlorobenzene
with dilute aqueous NaOH at 340°C under high pressure
The reaction involves an elimination reaction that gives a
triple bond in the ring: benzyne
29. 29
Structure of Benzyne
Benzyne is a highly distorted alkyne
The triple bond uses sp2
-hybridized carbons, not the
usual sp
The triple bond has one π bond formed by p–p
overlap and another by weak sp2
–sp2
overlap
30. 30
Oxidation of Aromatic Compounds
Alkyl side chains can be oxidized to CO2H by strong
reagents such as KMnO4 if they have a C-H next to the ring
Converts an alkylbenzene into a benzoic acid, ArR →
ArCO2H
A benzylic C-H bond is required, or no reaction takes place
31. 31
Bromination of Alkylbenzene Side Chains
Reaction of an alkylbenzene with N-bromo-succinimide
(NBS) and benzoyl peroxide (radical initiator) introduces
Br into the side chain only at benzylic position
32. 32
Reduction of Aromatic Compounds Aromatic rings are inert to catalytic hydrogenation under
conditions that reduce alkene double bonds
Can selectively reduce an alkene double bond in the
presence of an aromatic ring
Reduction of an aromatic ring requires more powerful
reducing conditions (high pressure or rhodium catalysts)
33. 33
Reduction of Aryl Alkyl Ketones
Aromatic ring activates neighboring carbonyl group
toward reduction
Ketone is converted into an alkylbenzene by catalytic
hydrogenation over Pd catalyst
34. 34
Synthesis of Trisubstituted Benzenes
These syntheses require planning and consideration of alternative
routes
Ability to plan a sequence of reactions in right order is valuable to
synthesis of substituted aromatic rings