Riemer Tiemann reaction

              Reimer Tiemann reaction 

Table contents:

History

About reaction

Mechanism

Comparasion

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History-

Riemer Tiemanm reaction is discovered by karl reimer ( 1845-1883 ) and Ferdinand Tiemann ( 1856-1883 ).

About reaction-

Riemer Tiemann reaction is substitution reaction . This reaction used for the orthoformylation of phenols.

When phenol is treated with chloroform in the presence of sodium hydroxide,an aldehyde group introduced at the ortho position. The reaction is called reimer tiemann reaction.

Mechanism-

1.Deprotonation of chloroform in the presence of strong base ( sodium hydroxide) 

And now chloroform carbanion forms.

2.chloroform carbanion undergoes alpha elimination and now dichlorocarbene formed as product.

3.sodium hydroxide deprotonates the phenol reagent.

4.Negative charged is delocalized into the benzene ring.

5. Nucleophile attack on the dochlorocarbene, forming an intermediate chloromethyl substituted phenol.

6.Finally we achieve hydroxy benzaldehyde.

👉👉 Phenol is converted into hydroxy benzaldehyde via chloroform.Carbene is highly electron deficient due to electron withdrawing nature of its two chlorine group.

Comaparasion to other methods-

Directly we can formylation of aromatic compounds bh various method such as the gattarmann reaction, gattarman koch reaction, and Duff reaction, haak reaction but the safety of reaction the Reimer Tiemann reaction is the most advantage routine in chemical synthesis.

➡️ Riemer Tiemann reaction can be useful to yield phenolic acids by carbon tetrachloride product will be salicylic acid rather than the salycyladehyde.

IITJAM 2022 exam pattern and prepration tips

                              IITJAM

1.What is IITJAM ?

 JAM ( joint admission test ) is an entrance test for masters which is conducted by IIT's or IISC banglore.

If you are interested in research then IITJAM exam is perfect for you . JAM offers you 2000+seats in IITs NITs and IISC for MSC + MSC PHD etc.

2. Subjects for IITJAM ?

There are total 7 subjects ( Physics, chemistry, mathematics, geology, biotechnology,mathematical statics economics ) 

*IISC banglore had added a new subject economics in 2021.

3. Qualification for IITJAM ?

🎓Nationalty - indian/overseas

🎓bechlors In science

🎓In qualifying degree aggregate at least 55% or 5.5 in out 10 for gen/obc.

 50% or 5.0 in out of 10 for sc/st.

Most of institute required maths in the 10+2 level.

4.What is JAM exam pattern ?

It's important to know about exam pattern .Exam paper is divided in three sections, every part/section have different pattern of questions as follows;

👉 Multiple choice question (MCQ) 

   In four options we can choose only one answer.

👉 Multiple Select answer (MSQ)

   In four options we can choose more than one answer.

👉 Numerical answer type (NAT)

  These questions do not have any option.NAT can be any numerical value or decimal or integer value …

5.About exam schedule ?

Time. 3 hours

Mode. online

Exam frequency.  once  a year

IITJAM exam preparation tips:

➡️Solve the previous year question.

➡️ Practice of mock test.

➡️Refer important book's question.

➡️Make short notes.

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friedal craft reaction and mechanism

                  Friedal-craft reaction

Table contents:

History

About reaction

Mechanism

Advantage

Limitations

Example

History-

Friedal craft reaction is discovered by charles friedal ( french scientist ) and james crafts ( American chemist ) in 1877.

About reaction-

Frieda crafts reaction is an electrophilic aromatic substitution reaction including organic coupling reaction. Friedal craft reaction are two type:

-Frieda craft alkylation

-Frieda craft acylation

This reaction involves the replacement of hydrogen atom via an electrophile.

The reactant for this reaction is aluminum trichloride, it is acts as Lewis acid and it is used in generating an electrophile in the process.

👉 Friedal craft alkylation:

This reaction helps in generating alkyl banene via alkyl halide as reactants. The catalyst is aluminum trichloride. Friedal craft alkylation indicate the replacement of an aromatic proton with an alkyl group.

In this reaction carbocation will be generate as intermediate.

Mechanism:

1.The formation of carbocation using Lewis acid aluminium trichloride.

2.Carbocation attack on the aromatic ring.

3.deprotonation of the intermediate will be. And the proton goes to on hydrochloric acid, regenerating aluminium trichloride catalyst.

👉 Frieda craft acylation:

It is the acylation of the aromatic rings, in this reaction involves the addition of the acyl group to aromatic ring. In this reaction reactant is the acid chloride and the catalyst is aluminium trichloride.The reaction is between benzene and acyl chloride under the condition. Lewis acid generate a highly electrophilic acylium kon which is stabilized by resonance.

Mechanism:

Step 1. Forming of acylium ion.

Step 2. Acylium ion attack on the aromatic ring and the aromaticity of the ring.

Step 3. Intermediate complex is deprotonated.

Step 4. Ketone product is formed adding water.

Advantage:

Acylation and alkylation are the advantage of friedal craft reaction.

Limitations:

Friedal craft reaction's limitations are carbocatiom rearrangement and polyalkyaltion . Acylation reaction yields only ketones.  Aryl amines can not be formed in this reaction.

Example

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Sandmayer Reactions , mechamism , example , uses

                       Sandmayer reaction

-Table of contents

: History

: About reaction

: Mechanism

:Uses

: Frenquely asked questions

: Example

-History

Traugott sandmayer ( swiss scientist ) discovered sandmayer  reaction in 1884 

during experiment to synthesize polyacetylene from benzene diazonium chloride and cuprous acetylide.

The product was phenylchloride of the Mr.sandmayer's reaction.

Reactant -aromatic amine

product  - arylhalide

Intermediate- nitrosamine

Reaction type - Radical nucleophilic aromatic substitution

Sandmayer reaction is the substitution reaction of an aromatic amino group.This substitution will be via nucleophile, proceed under Cooper catalysis.

Sanmayer reaction is used in the production of aryl halide.

It is used to transformation on benzene ( hydroxylation,trifluoromethylation,cynation, and halogenation )

-Mechanism

1.Formation of nitrosonium ion

2.Benzenediazonium formation 

Formation of nitrosonium ion

-at first we take sodium nitrate and acid 

-then water is removed in reaction

-nitrosonium ion reacts as an electrophile and it is reacted with an heterocyclic amine to form diazonium salt.

Benzenediazonium ion formation

-amine and nitrosonium ions will make benzenediazonium ion.

Uses:

-one important use is formation of an aryl halide

-It is used as synthesis of chloroform,iodoform etc.

Frenquely asked questions:

1.what type of sandmayer reaction?

 Ans: substitution reaction

2. Difference between sandmayer and gattarman reaction !

 Ans: In sandmayer reaction reactant is CuCl in HCl but in gattarman reaction reactant is CuCl or CuBr in chlorobenzene.

3.What is importance of sandmayer reaction?

 Ans: sandmayer reaction is important for transformation of benzene.

4.what is use of CuCl in sandmayer reaction ?

 Ans: It is react like nucleophile.

Example:

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Coordination compounds

                   Coordination compound

Those compounds that have a central metal which is an atom or ion form a coordinate bond with another neutral or ion, are called coordination-compounds.

Table of contents: 

1.Important terms

2.what is ligands and their types

3.oxidation number 

4.coordination polyhedron

5.homoleptic and heteroleptic complex

1. Key words

 

👉 Doublesalts- They are also called lattice compounds, these compounds are stable in solid state.

 Example - mohar salt

 👉 Complex compounds  - They are stable in both solid and solution states.

 👉 Central Ion - The cation or neutral metal atom that binds two or more anions or molecules is called a central ion.

 The central ion is the receiver.

👉 Coordinate Circles and Ionic Circles - The central metal and ligands are written in square brackets, this square bracket is called coordinate circle.

 The part outside the square bracket is called the ionic circle.

:What is a ligand and its types -

 Anions with single electron pairs are called ligands.

 The atom giving electron in the ligand is called donor atom.

  

1.monodentate ligand - those ligands that have only one donor.

 2. Bidentate ligands - containing two donor atoms.

 3. Tridentate ligand - containing three donor atoms.

 4. Quad ligand- containing four donor atoms.

 5.ambidentate ligand - monoental ligandthat has more than one donor atom.

Example- Nitro

 6. Chalate ligand- Polygonal ligand binds to two or more donor atoms with a central metal and forms a ring.

Example-ethylene diamine and oxalato

Oxidation number

 Rule-

 1. In neutral complex the sum of the charges of the central metal atom and the ligand is zero.

 2. Oxidation number is the sum of charges of metal atoms and ligands.

 Examples-

:Homoleptic and heteroleptic complex -

 In which donor atoms are attached to the same type of donor group, it is called homoleptic.

 In which donor atoms are attached to more than one type of donor groups, it is called heteroleptic complex.

:Coordination polyhedron - The arrangement of the ligands attached to the central metal is called the coordination polyhedron.

                    उपसहसयोंजक यौगिक

वे योगिक जिनमे केंद्रीय धातु जो परमाणु या आयन होता है अन्य उदासीन या आयन के साथ उपसहसयोंजक बन्ध बनाता है, उपसहसयोंजक योगिक कहलाते है। 

विषयसूची:

 1. प्रमुख शब्द

 2. लीगेंड क्या है और उनके प्रकार 

 3. ऑक्सीकरण संख्या

 4. समन्वय फलक

 5.होमोलेप्टिकऔर हेट्रोलेप्टिक कॉम्प्लेक्स 

1.प्रमुख शब्द

👉  द्विक लवण- इन्हें जालक यौगिक भी कहते है ये यौगिक ठोस अवस्था मे स्थायी होते है 

उदाहरण- मोहर साल्ट

👉संकुल योगिक- ये ठोस ओर विलयन अवस्था दोनों में स्थायी होते है।

उदाहरण- 

👉 केंद्रीय आयन - धनायन या उदासीन धातु परमाणु जिससे दो या उससे अधिक ऋणायन या अणु बंधित हो केंद्रीय आयन कहलाता है।

केंद्रीय आयन ग्राही होता है 

👉 समन्वय मंडल और आयनिक मंडल -  केंद्रीय धातु ओर लिगेंड को वर्गाकार कोष्ठक में लिखते है इस वर्गाकार कोष्ठक को समन्वय मंडल कहते है। 

वर्गाकार कोष्ठक के बाहर का भाग आयनिक मंडल कहलाता है। 

: लिगेंड क्या होता है और उसके प्रकार-

 एकांकी इलेक्ट्रान युग्म वाले ऋणायन, लिगेंड कहलाते है।

लिगेंड में इलेक्ट्रान देने वाला परमाणु दाता परमाणु कहलाता है।

1.एक दंतुक लीगेंड- वे लिगेंड जिनमे केवल एक ही दाता होता है। 

2.द्वि दंतुक लिगेंड- जिनमे दो दाता परमाणु हो।

3. त्रिदंतुक लीगेंड- जिनमे तीन दाता परमाणु हो। 

4.चतु दंतुक लीगेड- जिनमे चार दाता  परमाणु हो।

:  ऑक्सीकरण संख्या- 

नियम-

1. उदासीन संकुल में केंद्रीय धातु परमाणु ओर लिगेंड के आवेशों का योग शून्य होता है।

2.ऑक्सीकरण सँख्या धातु परमाणु ओर लिगेंडों के आवेशों का योग होता है। 

उदाहरण-

:होमोलेप्टिक ओर हेटेरोलेप्टिक संकुल-

  जिनमे दाता परमाणु एक ही तरह के दाता समूह से जुड़े होते है होमोलेप्टिक कहलाते है।

जिनमे दाता परमाणु एक से अधिक प्रकार के दाता समूहों से जुड़े रहते है हेटेरोलेप्टिक संकुल कहलाते है।

: समन्वय फलक- केंद्रीय धातु से जुड़े लिगेंडों की व्यवस्था को समन्वय फलक कहते है।