N-BROMOSUCCINAMIDE A REAGENT USED IN THE SYNTHESIS, IT IS ALSO A SYNTETIC REAGENT AND HERE IN THIS PRESENTATION THE MOLECULAR FORMULA ITS ALTERNATE NAME APLLICATION ARE DISCUSSED.
N-BROMOSUCCINAMIDE A REAGENT USED IN THE SYNTHESIS, IT IS ALSO A SYNTETIC REAGENT AND HERE IN THIS PRESENTATION THE MOLECULAR FORMULA ITS ALTERNATE NAME APLLICATION ARE DISCUSSED.
IMPORTANT NAMED REACTIONS in Organic synthesis with Introduction, General Mechanism, and their synthetic application covering more than 20 named reactions in it.
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Organic Synthesis:
The Disconnection Approach
One Group C-C Disconnection of Alcohol and Alkene
IMPORTANT NAMED REACTIONS in Organic synthesis with Introduction, General Mechanism, and their synthetic application covering more than 20 named reactions in it.
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
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Organic Synthesis:
The Disconnection Approach
One Group C-C Disconnection of Alcohol and Alkene
What is a Heterocyclic Compound?
A heterocyclic compound has at least two different elements as a member of its ring.
The most common hetero atoms found on a cyclic ring are Oxygen (O), Nitrogen (N) and Sulphur (S).
Example:
Nucleic Acid that is present in the body responsible for storing and expressing genetic information, is an example of a Heterocyclic compound.
Essential micronutrient, Vitamins is also an example of a heterocyclic compound.
The majority of drugs, pesticides, dyes, and plastics are examples of heterocyclic compounds.
Classification of Heterocyclic Compounds
Based on the electronic arrangement, we can classify Heterocyclic compounds into two types:
Aliphatic Heterocyclic Compounds
Aromatic Heterocyclic Compounds
Aliphatic Heterocyclic Compounds
Aliphatic heterocyclic compounds are those cyclic heterocycles that do not contain any double bond.
The properties of aliphatic heterocyclic compounds are mainly affected due to ring strain.
Examples of aliphatic heterocyclic compounds are Aziridine, Ethylene Oxide, Thiirane, Oxetane, Azetidine, Thietane, Tetrahydrofuran (THF), Dioxane, Pyrrolidine, Piperidine, etc.
Aromatic Heterocyclic Compound
Aromatic heterocyclic compounds, as the name suggests, are cyclic aromatic compounds.
Aromatic Heterocyclic compounds obey Huckels Rule, i.e.
It should be cyclic.
It should be planar.
It should not contain any sp3 hybridised atoms.
It must have (4n+2) 𝛑 electrons.
Aromatic Heterocyclic compounds are analogous to Benzene.
Examples: Furan, Pyrrole, Thiophene, Indole, Benzofuran, Carbazole, Quinoline, Isoquinoline, Imidazole, Oxazole, Pyrazole, Pyridazine, Pyrimidine, Purine, etc.
Based on structure, we can classify Heterocyclic compounds into five types:
Three-Membered Heterocyclic Compounds
Four-Membered Heterocyclic Compounds
Five-Membered Heterocyclic Compounds
Six-Membered Heterocyclic Compounds
Condensed or Fused Heterocyclic Compounds
Three-Membered Heterocyclic Compounds
These heterocyclic compounds contain three atoms which may be saturated or unsaturated.
Based on the number of heteroatoms present, we can further classify them into two categories:
Retrosynthesis or The Disconnection approach has been discussed in this presentation. Useful Courseware for the Undergraduate and Postgraduate students of Pharmacy , and Chemical Sciences
Purines are the cyclic diureides, consisting of a pyrimidine ring fused with an imidazole ring. Purine m.p. 212-213⁰C is a synthetic compound. Purine is not found naturally, but it’s derivatives, adenine, and guanine are found in nature. These are the building blocks of nucleic acid RNA and DNA. Purine can exist in four tautomeric forms in which the hydrogen atom is attached to the different nitrogen atom, N-1, N-3, N-7, and N-9. Purines are a type of chemical compound found in foods and drinks that are part of a normal diet. A small number of foods contain concentrated levels of purines, such as seafood, organ meats, and alcoholic beverages, especially beer.
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The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
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Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
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Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
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Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
1. lec6 1
Benzofuran (coumarone)
General properties
Benzo furan (1) some times called coumarone , is a colourless liquid b.p.137cº
which may be isoleted from coal tar .Its structure has not been investigated in
detail ,but it has aromatic properties and is best treated as a resonance hybrid
to which 1 is the major contributor ; minor contribution are made by charged
structure such as (1a) and (1b). Benzofuran is much more stable to chemical
attack than furan.
6
5
1
O
1
7
4
3
2
O
+
-
1a 1b
O
-
+
2. lec6 2
Chemical reaction
Oxidation
Benzofuran is much less easily opened than that of furan , but it can be spilt
by the two routes outlined .
O
O3
O
O
O2
C -R
O
OH
Mixture
R = H , OH
C CH
ONa
Na
3. lec6 3
2 – Electrophilic subistitution .
Benzofuran display a lesser tendency for 3 – subistitution for- mylation of
benzofuran reportedly gives only the 2-formly derivative and nitric acid nitration
produced 2 – nitrobenzofuran ;alater study using dinitrogen tetroxide give 3 –
nitrobenzofurane as amajor product togother with smaller percentage of the 2 –
isomer .
O
N2O4
PhH
10c0
O
NO2
+
O
HNO3
CH3COOH
O NO2
O NO2
59 % 14%
4. lec6 4
Treatment of benzofuran with halogens result in 2,3 – addition product with initial
electrophilic attacke taking place at c -2
O
X2
O
x
x
2,3 - dihalobenzofuran
O
(CH3CO)2O
BF3
O C - CH3
O
This is in very marked contrast to indole and thianphthene , where attack takes
place predominantly at position 3 , and has been attributed to the much
greater electronegative of oxygen than that of nitrogen or sulphur .
Some benzofurans even form 2,3 – epoxides with perbenzoic acid .
O O
O
epoxide
C6H5COOH
O
5. lec6 5
Reduction
Benzofuran is easily reduced by hydrogen over Palladium or sodium and alcohol
the 2,3 – dihydroderivative ,which is also known as coumaran
O O
2,3 - dihydroderiv
(coumaran)
red
H2/Pd
-H2
coumaran -2-one is the lacton of 2 – hydroxyphenyl acetic acid
CH2 - COOH
OH
O O
coumaran - 2 - one
(lactone )
-H2O
6. lec6 6
Synthesis of Benzofuran
1- A useful laboratory synthesis starts with coumaran ,and is generally applicable
O O
Br2
O O
H Br
Br
H
HO- K+
K / OH
-HBr
+ -
OH
CH
C - CO2K
Br
+
H
-HBr O COOH
Distile , CaO
-CO2 O
7. lec6 7
COR
O Na
C =O
O
R
CH2CO2Et
Br CH2CO2Et
-NaBr
NaOEt
-H2O
O COOEt
R
Decarboxylation
+H2O O
R
+ CO2 + EtOH
2- An internal claisen reaction may be used to bring about ring closure .
8. lec6 8
3- When the sodium derivative of etheyl salicylate is used the product is ethyl
coumaran -3-one -2-carboxylate which can be decarboxylated giving the best
synthesis of coumaran -3-one
C =O
ONa
OEt
Br CH2CO2Et
-NaBr
NaOEt
-EtOH
C = O
CH - COOEt
O
Decarboxylation
H2O
C =O
O
OEt
CH2- CO2Et
O
O
Coumaran-3-one-2-
carboxylate
Coumaran-3-one
9. lec6 9
Heterocyclic Analogues of benzen
with one hetero atom
The most important ring system of this class , that of pyridine , can be derived
from benzene by the replacement of a carbon and hydrogen atom by one of
nitrogen .This change leaves the aromatic structure of the rings essentially
unaltered .A similar replacement of carbon and halogen atoms by one of oxygen
cannot be envistigated because of valency consideration unless
Oxygen atom subsequently bears appositive charge .
N O O O
Pyridine Pyrylium
cation
1,2 - Pyran 1,4 - Pyran
S
1 - R - Thia (IV) benzene
R
+
S
S
Thiapyrylium
cation
1,4 - Thiapyuran
S
1,2-Thiapyuran
+
10. lec6 10
This is the case with the pyrylium cation , which has aromatic properties ,
Reduction of the pyrylium cation could lead to the non – aromatic 1,2 and 1,4
– pyrans and derivatives of both are known .Sulphur analognes of the pyrylium
salt and pyrans which are called thiapyrulium salt and thiapyrans, respectively,
and some unstable tetravalent sulphur containing compound , the thia (IV)
benzenes , have been prepared recently .
11. lec6 11
Pyridine
Pyridine was discover by Anderson , he isolated this base from bone
oil an he obtained pure picoline (methyl pyridine ) and Lutidine
(dimethylpyridine ) from the same source .
Compound containing the pyridine ring are widely distribute in nature ,
examples being Vatamine B6 and the nicotinamide, adenine ,
dinucleotide phosphate are of great biochemical importance , it also
feature in the structure of many drugs , dyes andalkaloide .
Pyridine is an aromatic compound similar to benzene .The
asymmetry of the ring , greatly increase the number of structural
isomers in comparison with the benzene .
N
.. +
-
N
..
..
+
-
N
..
.. -
N
..
..
N
12. lec6 12
N CH3 N
CH3
N
CH3
CH3
There is only one monomethylbenzene ,but there are three
monomethylpyridine .
Pyridine has 19 possible methyl substitution while benzene
gives rise to only 12 methylsub . benzene .
The position of subistituent around the pyridine ring are numbered (1) or
(2).The cation is called pyridinum and hexa hydropyridine is known as
piperidine .
N
H
N
2
N
1
2
3
4
5
6
1 Pyridinum
+
N
H
Piperidine
13. lec6 13
Structure of pyridine
In pyridine all ring atoms (five carbon and one nitrogen ) , are
sp2hybriization .Two of the sp2 orbitals in each atom overlap with each other to
from C – C an C – N σ bonds .
The third sp2 orbitals on each carbon atom overlap with an S orbital of hydrogen
to form the C – H σ bonds; the third sp2 orbital on nitrogen is occupied by two
electron (lone pair electrone ) i.e .sp2 orbital containing Nitrogen lone pair .All the
six bond in pyridine lie in one plane and the bond angles are approximately equal
to 120 cº .Also each ring atom in pyridine possesses an unhybridized p orbital
containing one electron and these are perpendicular to the plane containing the σ
bonds.
14. lec6 14
The latter overlap between two p orbitals produced a delocalized π molecular
orbital containing six electrons (Aromatic character ) one half of this π molecular
orbital lies above and the other half below the plane of σ bonds . Pyridine show
some aromatic properties because the resulting molecular orbitals satisfies the
Huckel's rule ( n = 1 in 4n+2) .
According to the resonance theory ,pyridine is considered to be hybrid of
five structure as shown before .
Measurement of bond length by x – ray confirms the hybrid nature of the pyridine
molecule .The C – C and C – N bond lengths of 1.39 Aº an 1.57 Aº are
intermediate between those corresponding to a single and double bond .
15. lec6 15
Physical properties
Pyridine is a colour less liquid , b.p 115Cº . It has a very pungent
dour , pyridine is miscible with water and most organic solvent it is very
hygroscopic .Pyridine react with Na and so should be dried over solid
potassium hydroxide or barium oxide .Almost all classes of organic
compound are soluble in pyridine , even many of high melting solids which
scarcely dissolve in solvents such as ethanol and benzene .It is
consequently used as a solvent
