The document discusses organomagnesium halides (Grignard reagents). It describes how Grignard reagents are useful synthetic intermediates for carbon-carbon bond formation and are sources of nucleophilic carbanions. It summarizes several reactions of Grignard reagents including additions to carbonyl compounds, substitutions of alkyl/alkenyl/aryl halides, synthesis of ethers, amines, aldehydes and more. It also discusses the mechanisms and applications of important Grignard reactions such as the Bouveault, Benary, Bodrous, Dzhemilev and Kulinkovich reactions.
Organolithium compounds and their preparation.pptxZaeem36
Here, the detailed explanation of organolithium compounds in this presentation you will find out about:
organolithium introduction
-Preparation
-Properties
-And their useful Reactions,
for more projects and any kind of presentations you can contact us at:
zaeem.bzn@gmail.com
This PPT is usefull for aspirants of JEE-IIT, CSIR-NET and UPSC exams in CHEMISTRY section. It is also usefull for grduates and Post graduates students of Indian Universities.
Organolithium compounds and their preparation.pptxZaeem36
Here, the detailed explanation of organolithium compounds in this presentation you will find out about:
organolithium introduction
-Preparation
-Properties
-And their useful Reactions,
for more projects and any kind of presentations you can contact us at:
zaeem.bzn@gmail.com
This PPT is usefull for aspirants of JEE-IIT, CSIR-NET and UPSC exams in CHEMISTRY section. It is also usefull for grduates and Post graduates students of Indian Universities.
SMILES REARRANGEMENT [REACTION AND MECHANISM]Shikha Popali
THE SMILES REARRANGMENT IS THE PROCESS OF REARRANGING OF ELEMENTS OF THE STRUCTURE, WHERE IN THIS PRESENTATION HOW TO REARRANGE IS EXPLAIN WITH ITS MECHANISM
SMILES REARRANGEMENT [REACTION AND MECHANISM]Shikha Popali
THE SMILES REARRANGMENT IS THE PROCESS OF REARRANGING OF ELEMENTS OF THE STRUCTURE, WHERE IN THIS PRESENTATION HOW TO REARRANGE IS EXPLAIN WITH ITS MECHANISM
Coupling Reactions Part 2 - Shafna Jose, St. Mary's College, ThrissurShafnaJose
Suzuki – Miyaura coupling, Sonogashira coupling ,Stille coupling, Negishi coupling
Suzuki Miyaura- Pd catalyzed cross coupling reaction of organoboron compounds with organic halides.
Sonogashira coupling - coupling of a terminal alkynes with aryl or vinyl halides with a Pd catalyst,a Cu(1) co-catalyst and an amine base.
Stille coupling- Pd catalyzed cross coupling reaction involving organotin based reagents and organohalides.
Coupling reaction involves the joining of two chemical species with the help of a metal catalyst.
An important type of coupling reaction is the reaction of an organic halide with an organometallic compound which facilitates the formation of a new carbon-carbon bond.
Diel's-Alder and Gattermann Koch ReactionsPRUTHVIRAJ K
n organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a pericyclic reaction with a concerted mechanism
The delocalization of σ-electron in to adjacent π orbital or p-orbital is called hyperconjugation. The contributing structures involving sigma electrons of C - H bond do not show any covalent bond between C and H. Hyperconjugation, therefore, is also called as "no bond resonance" or "Baker-Nathan effect
Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. Compounds that contain an indole ring are called indoles.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
2. • The organomagnesium halides (RMgX), known as
Grignard reagents.
• (RMgX ) are useful synthetic intermediates in organic
chemistry for carbon-carbon bond formation.
• They may be regarded as polar compounds and are
sources of nuleophilic carbanions.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
3. General
• Although the Grignard reagents are usually formulated
as R-Mg-X, but in reality they are a mixture of a variety
of species.
• The ratio of the species in solution varies with the
organic group, the halogen, the solvent, the concentration
and the temperature.
• It is believed that in case of organo-magnesium chlorides
(R-Mg-Cl) in diethyl ether, the predominant species over a
wide range of concentrations is a solvated, halogen-
bridged dimer -1 (as shown in next slide).
•The degree of association varies as the halide is changed
to Br or I.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
4. • However, in case of THF, due to the highly coordinating
nature of the solvent, there is a lesser degree of association.
• Therefore, monomeric species dominate in THF, however,
there are significant concentrations of R2Mg, MgX2 and
R-Mg-X in equilibrium.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
5. Preparation
• The RMgX are prepared by the action of Mg on alkyl, aryl
or vinyl halides in either dry ether or THF, and the
resultant solution is used for the subsequent reactions.
• In case the reaction is sluggish, small amount of iodine is
added to initiate the reaction.
• The rate of the formation of the organomagnesium halides
can be significantly accelerated by sonication.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
6. Reactions with Carbonyl Compounds
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
7. Mechanism
• Being nucleophilic in nature, the R-Mg-X undergo 1,2-
addition to the carbonyl group of aldehydes, ketones,
esters, anhydrides, acid chlorides and amides.
• In these reactions, the alkyl, aryl or vinyl group having
carban-ionic character become attached to the carbonyl
carbon and the Mg-X to the oxygen of the carbonyl
group to give a complex (addition product).
• These addition products on decomposition with proton
source give the corresponding alcohols.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
8. The mechanism of this reaction is usually depicted to consist
of the following steps-
•Complexation of the organomagnesium species with the
substrate.
•The next step involves nucleophilic attack of organic
moiety of Grignard reagent on the electron deficient
carbon of carbonyl group via a molecular complex.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
9. •The intermediate formed in the above step is hydrolyzed to
give a tertiary alcohol. However, if the carbonyl group is
attached with a leaving group (i.e., if R1= OR) then the
tetrahedral adduct can break down to regenerate a C=O
group that undergoes a fast second addition step.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
11. A number of methods have been devised to stop the reaction at the
aldehyde or ketone stage. Such protocols involve the formation of a
masked carbonyl compound, which releases the desired compound on
hydrolysis.
Mechanism cont….
Scheme-3
H+ / H2O
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
12. Mechanism cont….
In case of reaction of Grignard reaction with carbon
dioxide, the reaction stops at the carboxy-late (RCO2
-)
stage as it is resistant to further nucleo-philic attack
Scheme-4
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
13. • Grignard reactions are prone to undergo side reactions.
• The reaction of a sterically hindered ketone with a
Grignard reagent having a β-H shows a tendency
towards reduction of the carbonyl group.
Scheme-5
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
14. Reactions with Epoxides
• Epoxides react with R-Mg-X to afford a primary alcohol with the
lengthening of the carbon chain by two carbon atoms.
• However, in this case of substituted epoxides, the attack of the alkyl,
aryl or vinyl caban-ion takes place from the less substituted ring
carbon (steric factor) atom of the epoxides.
Scheme-6
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
15. Reactions with Alkyl/Alke-nyl/Aryl Halides
Alkyl, alke-nyl as well as aryl triflates, bromides, and iodides can proceed
substitution reactions with R-Mg-X in the presence of transition metal
catalysts. For examples, CoCl2 catalyzes the cross-coupling of Ph-Mg-Br
with benzyl bromide in 87% yield (Kharasch reaction).
Scheme-7
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
16. • The coupling of alkenyl halides with R-Mg-X can be successfully
carried out in the presence of NiCl2(dppe) in high yield.
• In these reactions the existing configuration of the stereo-genic
double bond is completely retained.
• These reaction conditions are also compatible for the cross-
coupling aryl halides/triflates with aryl-magnesium halides.
Scheme-8
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
18. The C-C cross-coupling of secondary R-Mg-X may occur in analogy
to the reaction of the primary R-Mg-X, but they may also lead to the
unexpected reactions depending on the catalytic system due to steric
hindrance that could lead to iso-meriazation of the C-C coupling.
Scheme-10
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
20. Synthesis of Ethers
R-Mg-X with lower halogenated ethers produce higher ethers.
Scheme-11
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
21. Synthesis of Stilbene
The synthesis of stilbene can be accomplished by the reaction
of benzyl-magnesium bromide(PhCH2MgBr) with benzal-
dehyde, followed by dehydration under acidic or basic
conditions.
Scheme-12
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
22. Synthesis of Alkyl cyanide
The reaction of alkyl-magnesium halides with cyanogens or
cyanogens chloride gives alkyl cyanides .
Scheme-13
chloride
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
23. Synthesis of Primary Amines
The reaction of chloramines with organomagnesium halides
gives primary amines.
Scheme-14
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
24. Scheme-15
Synthesis of Deutrated Hydrocarbons
Deutrated hydrocarbons can be synthesized by the
reaction of organomagnesium halides with D2O
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
25. Scheme-16
Benary Reaction
It provides an effective method for the synthesis of α,β-
unsaturated carbonyl compounds from -β (N,N-
dialkylamino)-vinyl ketone and Grignard reagent by 1,4-
addition followed by hydrolysis and elimination of the
dialkylated amine.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
26. Bodrous Reaction
This reaction provides a method for the preparation of substituted amides
from aliphatic or aromatic esters and an aminomaganesium halide which
can be obtained from a primary or secondary amine and Grignard reagent
at room temperature.
Scheme-17
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
27. Scheme-18
Bouveault Reaction
Primary alkyl halide can be converted into aldehydes with
an additional carbon via the formation of Grignard reagent
followed by reaction with N,N-disubstituted formamide and
hydrolysis.
Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
28. Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
Scheme-19
Dzhemilev Reaction
It involves the reaction of alkenes with Grignard reagent to
give alkyl magnesium halide in the presence of Cp2ZrCl2.
This method had found wide application in organic and
organometallic synthesis.
29. Dr. Mishu Singh
Pt. D. D. U Govt. Girls P.G. College, Lucknow
Scheme-19
Kulinkovich Reaction
The reaction of esters with di-alkyl-dialkoxy-titanium
reagents, generated in situ from Grignard reagents bearing
hydrogen in β-position and titanium(IV) alkoxides such as
titanium isopropoxide, gives cyclopropanols.
