Concept explainers
Interpretation:
A step by step mechanism for both the transformation of Robinson annulation sequence is to be provided, and the acidity of
Concept introduction:
Electrophiles are electron deficient species that have positive or partially positive charge. Lewis acids are electrophiles that accept electron pair.
Nucleophiles are electron rich species that have negative or partially negative charge. Lewis bases are nucleophiles that donate electron pair.
Free radical is an atom, molecule, or ion that has an unpaired electron that makes it highly chemically reactive.
Substitution reaction: A reaction in which one of the hydrogen atoms of a hydrocarbon or a
Elimination reaction: A reaction in which two substituent groups are detached and a double bond is formed is called elimination reaction.
Addition reaction: It is the reaction in which unsaturated bonds are converted to saturated molecules by the addition of molecules.
A base removes acidic hydrogen and forms an enolate.
The enolate adds to the
A carbon–carbon bond formation occurs by aldol addition and aldol condensation reaction.
An aldol reaction takes place in a protic solvent with a base.
An aldol reaction takes place by acid catalysis, and direct dehydration of
A
A chemical reaction that is catalyzed by a base is called base catalyzed reaction.
Aldol reaction is preferred in basic condition over acidic condition, as after the aldol condensation, acid catalysis promotes the reaction further.
In Robinson annulation reaction, Michael addition, followed by simple aldol condensation, takes place.
The Robinson annulation reaction is used to form one ring on to another.
A resonance structure which stabilize the conjugate base also increases the acidity.
The rules for drawing resonance structures are as:
Only nonbonding electron pairs and pi electrons can participate in conjugation in the formation of various resonating structures.
The single bonds present in the molecule do not break or form in the resonance structures.
The placement of atoms present in the molecule remains fixed.
The octet of all atoms is completely filled.
More the number of resonance structures indicate higher stability of a compound.
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Organic Chemistry
- Nucleophilic aromatic substitution provides one of the common methods for making phenols. ) Show how you would synthesize the following phenols, using benzene or toluene as your aromatic starting material, and explain why mixtures of products would be obtained in some cases. (a) m-cresol (b) p-n-butylphenolarrow_forwardPractice Problem 18.39 Rank the following compounds in order of increasing reactivity toward electrophilic aromatic substitution. Br A B Br Br E Increasing reactivity toward electrophilic aromatic substitutionarrow_forwardNucleophilic aromatic substitution provides one of the common methods for making phenols. Show how you would synthesize the following phenols, using benzene or toluene as your aromatic starting material, and explain why mixtures of products would be obtained in some cases.(a) p-nitrophenol (b) 2,4,6-tribromophenol (c) p-chlorophenolarrow_forward
- (a) How will you obtain the following :(i) Benzaldehyde from Phenol (ii) Benzoic acid from Aniline(b) Give reasons :(i) Aldehydes are more reactive than ketones towards nucleophilic reagents.(ii) Electrophilic substitution in benzoic acid takes place at meta position.(iii) Carboxylic acids do not give the characteristic reactions of carbonyl group.arrow_forwardRank the compounds in each of the following groups in order of their reactivity to electrophilic substitution: (a) Nitrobenzene, phenol, toluene, benzene (b) Phenol, benzene, chlorobenzene, benzoic acid (c) Benzene, bromobenzene, benzaldehyde, anilinearrow_forwardShow how you would synthesize the following compounds, starting with benzene or toluene and any necessary acyclic reagents. Assume para is the major product (and separable from ortho) in ortho, para mixtures.(a) p-aminobenzoic acid (b) 2-methyl-1-phenylbutan-2-ol (c) 5-chloro-2-methylanilinearrow_forward
- When phenyl 3,4-dimethylbenzoate undergoes electrophilic aromatic substitution, one ring reacts much more readily than the other. (a) Which one is it? Encircle the ring (b) Explain your answer. (c) Draw the resulting product/s when it undergoes bromination reaction. Product (c) (a) Explanation (b)arrow_forwardThe following questions concern ethyl (2-oxocyclohexane)carboxylate.(a) Write a chemical equation showing how you could prepare ethyl (2-oxocyclohexane)-carboxylate by a Dieckmann cyclization.(b) Write a chemical equation showing how you could prepare ethyl (2-oxocyclohexane)-carboxylate by acylation of a ketone.(c) Write structural formulas for the two most stable enol forms of ethyl (2-oxocyclohexane)carboxylate.(d) Write the three most stable resonance contributors to the most stable enolate derived from ethyl (2-oxocyclohexane)carboxylate.(e) Show how you could use ethyl (2-oxocyclohexane)carboxylate to prepare 2-methylcyclohexanone.(f) Give the structure of the product formed on treatment of ethyl (2-oxocyclohexane)-carboxylate with acrolein (H2C=CHCH=O) in ethanol in the presence of sodium ethoxidearrow_forward19.73 Propose an efficient synthesis for each of the following transformations: (a) 0-0 (b) (c) Br -arrow_forward
- Compound A undergoes an acid-catalyzed hydrolysis. One of the products (B) that is isolated gives the following 1H NMR spectrum. Identify the compounds A and Carrow_forwardStarting exactly with any acid chloride with exactly with 5 carbon atoms, and using appropriate reagents outline the synthesis of the following molecules: (a) 2,6-dimethyl-4-heptanone (b) 4-propyl-4-octanolarrow_forwardShow how you would synthesize the following compounds, starting with benzene or toluene and any necessary acyclic reagents. Assume para is the major product (and separable from ortho) in ortho, para mixtures. (a) 3-nitro-4-bromobenzoic acid (b) 3-nitro-5-bromobenzoic acid (c) 4-butylphenol (d) 2-(4-methylphenyl)butan-2-olarrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning