Heterocyclics

<p>One hydrogen is replaced by a lone pair on nitrogen.</p> Signup and view all the answers

<p>Any atom in an organic molecule that is nitrogen, oxygen, or sulfur.</p> Signup and view all the answers

<p>Nicotine</p> Signup and view all the answers

<p>115 °C</p> Signup and view all the answers

<p>They behave as secondary amines.</p> Signup and view all the answers

<p>It lacks hydroxyl groups.</p> Signup and view all the answers

<p>Pyrrolidine</p> Signup and view all the answers

<p>They tie back into the ring, reducing steric hindrance.</p> Signup and view all the answers

<p>Pyridine remains aromatic even in charged states.</p> Signup and view all the answers

<p>Cyclohexane</p> Signup and view all the answers

<p>It is 60 times faster as a nucleophile.</p> Signup and view all the answers

<p>Monocyclic saturated heterocycles.</p> Signup and view all the answers

<p>They are essential in the structure of drugs and biologically active molecules.</p> Signup and view all the answers

<p>sp3 hybridized</p> Signup and view all the answers

<p>Axial and equatorial</p> Signup and view all the answers

<p>Pethidine</p> Signup and view all the answers

<p>Approximately 2/3 of organic compounds</p> Signup and view all the answers

<p>C-N bonds are shorter than C-C bonds</p> Signup and view all the answers

<p>Applies to cyclic systems with (4n+2) p-electrons</p> Signup and view all the answers

<p>It enables piperidine to act as a base</p> Signup and view all the answers

<p>Phenylcyclohexylpiperidine</p> Signup and view all the answers

<p>They are close to 109.5°</p> Signup and view all the answers

<p>sp3 hybridized</p> Signup and view all the answers

<p>Heterocycles are crucial in drug design due to their biological activity and ability to interact with biological targets.</p> Signup and view all the answers

<p>Saturated nitrogen-containing heterocycles behave as secondary amines and act as nucleophiles in addition and substitution reactions.</p> Signup and view all the answers

<p>The pKa value indicates the strength of the acid formed by the heterocycle, influencing its basicity; higher pKa values signify stronger bases.</p> Signup and view all the answers

<p>A heteroatom is any atom in an organic molecule that is not carbon (C) or hydrogen (H).</p> Signup and view all the answers

<p>Fused ring systems with one heteroatom contain a single heteroatom in a ring structure, while those with multiple heteroatoms include two or more heteroatoms in the rings.</p> Signup and view all the answers

<p>The R groups influence the steric hindrance around the nitrogen atom, thus affecting its nucleophilicity and basicity.</p> Signup and view all the answers

<p>Quinuclidine is 60 times faster than triethylamine when acting as a nucleophile.</p> Signup and view all the answers

<p>Five-membered aromatic heterocycles typically include heteroatoms and can exhibit unique stability and reactivity due to their aromatic nature.</p> Signup and view all the answers

<p>Conformation A (equatorial H on N) and Conformation B (axial H on N).</p> Signup and view all the answers

<p>Conformation A is slightly more stable than Conformation B.</p> Signup and view all the answers

<p>The lone pair of electrons on nitrogen allows it to accept protons.</p> Signup and view all the answers

<p>Pyridine has C-N bonds that are shorter than C-C bonds.</p> Signup and view all the answers

<p>Aromatic compounds must be planar, fully conjugated, and contain $(4n+2)$ p-electrons.</p> Signup and view all the answers

<p>Pethidine (Demerol), classified as an analgesic.</p> Signup and view all the answers

<p>Nitrogen in aromatic heterocycles is typically sp2 hybridized.</p> Signup and view all the answers

<p>Heteroaromatic compounds exhibit added stability due to aromaticity.</p> Signup and view all the answers

<p>Nitrogen's higher electronegativity leads to a distortion in bond lengths and creates a dipole.</p> Signup and view all the answers

<p>Carbon atoms in piperidine are sp3 hybridized.</p> Signup and view all the answers

<p>Pyridine is electron deficient due to the permanent dipole towards the nitrogen atom, causing fractional positive charges on the ortho and para carbons.</p> Signup and view all the answers

<p>The lone pair on nitrogen is not delocalized and is available for bonding, which imparts basic properties to pyridine.</p> Signup and view all the answers

<p>Pyridine has a boiling point of 115 °C, which makes it higher than many common organic solvents.</p> Signup and view all the answers

<p>Pyridine undergoes nucleophilic substitution reactions more readily than benzene due to its electron-deficient nature.</p> Signup and view all the answers

<p>The pyridinium cation retains its aromaticity even after it accepts a proton.</p> Signup and view all the answers

<p>The pKa of pyridine is 5.23, indicating that its conjugate acid is as strong as a carboxylic acid.</p> Signup and view all the answers

<p>The presence of the nitrogen atom makes pyridine electron-poor, thus affecting its reactivity profile and favoring nucleophilic substitution.</p> Signup and view all the answers

<p>Pyridine contains a nitrogen atom that replaces one of the carbon atoms in the benzene ring.</p> Signup and view all the answers

<p>Nitrofurantoin</p> Signup and view all the answers

<p>Benzene is more stable due to greater resonance energy.</p> Signup and view all the answers

<p>Quinoline</p> Signup and view all the answers

<p>Pyrrole has the highest resonance energy.</p> Signup and view all the answers

<p>Aromatic amines</p> Signup and view all the answers

<p>Suprofen</p> Signup and view all the answers

<p>It is less basic than quinoline.</p> Signup and view all the answers

<p>It stabilizes the compound.</p> Signup and view all the answers

<p>Their lone pairs contribute to the aromatic system.</p> Signup and view all the answers

<p>C-2 position</p> Signup and view all the answers

<p>Electron density is withdrawn from the nitrogen atom.</p> Signup and view all the answers

<p>Their lone pair is part of the aromatic system.</p> Signup and view all the answers

<p>They follow Hückel's Rule for aromaticity.</p> Signup and view all the answers

<p>sp2, allowing for planar structure.</p> Signup and view all the answers

<p>It makes it resistant to electrophilic attack.</p> Signup and view all the answers

<p>They contain sulfur or oxygen instead of nitrogen.</p> Signup and view all the answers

<p>C-1 position</p> Signup and view all the answers

<p>Antimalarial</p> Signup and view all the answers

<p>Linear tricyclic system</p> Signup and view all the answers

<p>It is an anticoagulant.</p> Signup and view all the answers

<p>Morphine</p> Signup and view all the answers

<p>Aromatic system</p> Signup and view all the answers

<p>Quinine</p> Signup and view all the answers

<p>Six-membered oxygen-containing ring</p> Signup and view all the answers

<p>Deprotonates as a base</p> Signup and view all the answers

<p>Quercetin</p> Signup and view all the answers

<p>The lone pair is part of the delocalized p-electron system, contributing to its aromatic nature and making it unavailable for bonding.</p> Signup and view all the answers

<p>They have 4 p-electrons plus 3 pairs of delocalized p-electrons, satisfying the 4n+2 condition for aromaticity.</p> Signup and view all the answers

<p>It predominantly occurs at the C-2 position (C-5).</p> Signup and view all the answers

<p>Thiophene has a planar structure and follows Hückel's rule with its delocalized p-electrons.</p> Signup and view all the answers

<p>The nitrogen in pyrrole draws electron density towards itself, increasing the electron density in the p-cloud.</p> Signup and view all the answers

<p>Pyrrole is less basic than pyridine because its lone pair of electrons is involved in aromatic stability and not available for bonding.</p> Signup and view all the answers

<p>Planarity is crucial for the overlap of p-orbitals, facilitating aromatic resonance and stabilization.</p> Signup and view all the answers

<p>Their aromatic character and electron-rich nature make them highly reactive towards electrophiles.</p> Signup and view all the answers

<p>C-2 and C-4 positions.</p> Signup and view all the answers

<p>C-1 position only.</p> Signup and view all the answers

<p>Quinine is used as an anti-malarial drug.</p> Signup and view all the answers

<p>It is used as an antibacterial topical antiseptic.</p> Signup and view all the answers

<p>Warfarin is a coumarin, primarily used as an anticoagulant.</p> Signup and view all the answers

<p>Both are widely distributed throughout the plant kingdom.</p> Signup and view all the answers

<p>The lone pair of electrons does not contribute to bonding and can deprotonate as a base.</p> Signup and view all the answers

<p>Basicity influences the reactivity and interaction of these compounds with biological systems.</p> Signup and view all the answers

<p>Coumarin features a benzopyrone structure that allows for aromatic properties.</p> Signup and view all the answers

<p>Quercetin acts as an antioxidant.</p> Signup and view all the answers

<p>Higher resonance energy indicates greater electron delocalization, leading to increased stability of the compound.</p> Signup and view all the answers

<p>The benzene ring is more nucleophilic due to its electron-rich structure, making it more reactive than the electron-deficient pyridine ring.</p> Signup and view all the answers

<p>Fused six-membered rings enhance the stability and reactivity of benzopyridines by maintaining aromatic character.</p> Signup and view all the answers

<p>Isoquinoline has a pKa of 5.14 and quinoline has a pKa of 4.85, indicating isoquinoline is slightly less acidic and more basic than quinoline.</p> Signup and view all the answers

<p>Pyrrole, furan, and thiophene contain heteroatoms that provide unique electronic properties compared to benzene's purely hydrocarbon structure.</p> Signup and view all the answers

<p>Sulfur, nitrogen, and oxygen have varying resonance stabilization effects, with sulfur being more reactive due to its larger atomic size which enhances electrophile attraction.</p> Signup and view all the answers

<p>Heteroatoms can disrupt aromaticity by altering the electron distribution, which can either enhance or reduce stability depending on their position.</p> Signup and view all the answers

<p>Planar aromatic compounds contain a continuous loop of p orbitals with $(4n + 2)$ $ ext{π}$ electrons, satisfying Hückel's rule for aromaticity.</p> Signup and view all the answers

<p>Thymine</p> Signup and view all the answers

<p>Barbiturates lack lone pair electrons available for bonding.</p> Signup and view all the answers

<p>Lower pKa correlates with weaker basicity, influencing binding affinity.</p> Signup and view all the answers

<p>They serve as nucleoside components in antiviral and anticancer agents.</p> Signup and view all the answers

<p>The nitrogen atoms disrupt the delocalization of electrons.</p> Signup and view all the answers

<p>Imidazole</p> Signup and view all the answers

<p>7.1</p> Signup and view all the answers

<p>Ability to donate and accept hydrogen bonds</p> Signup and view all the answers

<p>It is an essential amino acid</p> Signup and view all the answers

<p>Oxacillin</p> Signup and view all the answers

<p>It has a highly symmetrical structure</p> Signup and view all the answers

<p>Imidazole is more basic due to its resonance structure</p> Signup and view all the answers

<p>Pyrazole</p> Signup and view all the answers

<p>Perfect symmetry with equal charge sharing</p> Signup and view all the answers

<p>It facilitates interactions in enzyme mechanisms</p> Signup and view all the answers

<p>The lone pair of electrons contributes to the aromatic pi cloud.</p> Signup and view all the answers

<p>5-Hydroxytryptophan (5-HTP)</p> Signup and view all the answers

<p>It allows substitution at both C-2 and C-3 positions.</p> Signup and view all the answers

<p>2.5, indicating it is a strong base.</p> Signup and view all the answers

<p>Indomethacin</p> Signup and view all the answers

<p>It contributes electrons to the aromatic sextet.</p> Signup and view all the answers

<p>Imidazole has a higher pKa than thiazole.</p> Signup and view all the answers

<p>Electronegativity of the heteroatom.</p> Signup and view all the answers

<p>It plays a crucial role in the aromatic sextet.</p> Signup and view all the answers

<p>Isoxazole</p> Signup and view all the answers

<p>Pyrimidines are crucial for the structure of nucleic acids, including DNA and RNA, specifically exemplified by uracil, thymine, and cytosine.</p> Signup and view all the answers

<p>The lone pair of electrons in indole contributes to the p cloud, making it part of the aromatic system.</p> Signup and view all the answers

<p>The substituents at the 5-position in barbiturates modify their pharmacological properties, affecting their potency and duration of action.</p> Signup and view all the answers

<p>Barbituric acid lacks sufficient substituents that provide the pharmacological activity typically observed in its derivatives.</p> Signup and view all the answers

<p>Substitution primarily occurs at the C-3 position.</p> Signup and view all the answers

<p>In both pyrimidines and barbiturates, the lone pairs on nitrogen are not available for bonding, making them weak bases.</p> Signup and view all the answers

<p>Indole does not act as a base because its lone pair is involved in the aromatic p cloud rather than being available for protonation.</p> Signup and view all the answers

<p>Tryptophan is an essential amino acid and a precursor to serotonin.</p> Signup and view all the answers

<p>Pyrimidones contain a carbonyl group and are derived from pyrimidines, which lack this functional group.</p> Signup and view all the answers

<p>Indomethacin is primarily used as an anti-inflammatory drug.</p> Signup and view all the answers

<p>The pKa values indicate the acidity and basicity of the azoles, affecting their reactivity and role in biological systems.</p> Signup and view all the answers

<p>In both pyrazole and imidazole, the nitrogen at the 1-position contributes electrons to the aromatic sextet, making them non-basic.</p> Signup and view all the answers

<p>LSD mimics serotonin due to its structural similarity, allowing it to interact with serotonin receptors in the brain.</p> Signup and view all the answers

<p>The reactivity differences arise from the electronegativity of the heteroatoms (O in benzofuran and S in benzothiophene).</p> Signup and view all the answers

<p>The pKa values around 7-8 indicate that these compounds can donate protons, thus displaying weak acidic properties in solutions.</p> Signup and view all the answers

<p>Their unique chemical behavior, including varied reactivity and ability to form hydrogen bonds, allows them to interact effectively with biological targets.</p> Signup and view all the answers

<p>AZT, or Zidovudine, is an antiretroviral medication that inhibits reverse transcriptase, which is crucial for HIV replication.</p> Signup and view all the answers

<p>Piperidine acts as a base due to the availability of a lone pair of electrons on the nitrogen atom, which can accept protons.</p> Signup and view all the answers

<p>Trimethoprim is a bacteriostatic antibiotic that inhibits bacterial dihydrofolate reductase, disrupting the synthesis of folate and ultimately hindering bacterial growth.</p> Signup and view all the answers

<p>Imidazole is a stronger base than pyrazole due to the resonance stabilization in imidazole, which allows it to better share the positive charge.</p> Signup and view all the answers

<p>The pKa of imidazole is approximately 7, indicating it is 50% protonated in neutral water.</p> Signup and view all the answers

<p>Imidazole can both donate and accept hydrogen bonds, similar to water, which is crucial for enzyme activity utilizing the imidazole ring.</p> Signup and view all the answers

<p>The symmetry in imidazole's structure leads to equal charge distribution, enhancing stability.</p> Signup and view all the answers

<p>They differ in the positioning of nitrogen atoms within the ring structure, affecting their chemical properties.</p> Signup and view all the answers

<p>Imidazole derivatives are important in medication, acting as base structures in drugs like cimetidine and dantrolene.</p> Signup and view all the answers

<p>In pyrazole, the electron-withdrawing effect makes it a weaker base compared to imidazole, which benefits from resonance.</p> Signup and view all the answers

<p>1,2-Diazines are stable and colorless compounds, making them soluble in water due to their polar nature.</p> Signup and view all the answers

<p>Pyridazine has a pKa of 2.3, pyrimidine 1.3, and pyrazine 0.65, indicating that pyrazine is the strongest acid among them.</p> Signup and view all the answers

<p>Imidazole's basicity allows it to act as a proton acceptor in various biochemical reactions, aiding enzyme catalysis.</p> Signup and view all the answers

<p>C6H4N4 with a fused pyrimidine and pyrazine ring system</p> Signup and view all the answers

<p>It is crucial for the production of healthy red blood cells.</p> Signup and view all the answers

<p>Pteridine combines with PABA to form pteroic acid.</p> Signup and view all the answers

<p>Methotrexate</p> Signup and view all the answers

<p>Location of lone pair electrons on nitrogen atoms</p> Signup and view all the answers

<p>They connect the purine and pyrimidine bases together.</p> Signup and view all the answers

<p>Uracil</p> Signup and view all the answers

<p>Adenine and Thymine</p> Signup and view all the answers

<p>Treatment for leukemia</p> Signup and view all the answers

<p>Theobromine</p> Signup and view all the answers

<p>It serves as a nitrogenous waste excretion method mainly in birds.</p> Signup and view all the answers

<p>Enhances cognitive function and alertness</p> Signup and view all the answers

<p>Acyclovir</p> Signup and view all the answers

<p>They act as constituents of nucleic acids and as signaling molecules.</p> Signup and view all the answers

<p>Purines contain two fused rings while pyrimidines have a single ring.</p> Signup and view all the answers

<p>Adenine pairs with Thymine.</p> Signup and view all the answers

<p>It has two strands with a sugar-phosphate backbone.</p> Signup and view all the answers

<p>They can undergo both electrophilic and nucleophilic attacks.</p> Signup and view all the answers

<p>Catalyzing biochemical reactions.</p> Signup and view all the answers

<p>Adenine.</p> Signup and view all the answers

<p>They differ by the number of phosphate groups.</p> Signup and view all the answers

<p>Cytosine.</p> Signup and view all the answers

<p>Single-stranded structure.</p> Signup and view all the answers

<p>Adenine pairs with Thymine and Guanine pairs with Cytosine.</p> Signup and view all the answers

<p>Uracil replaces thymine in RNA, pairing with adenine.</p> Signup and view all the answers

<p>Xanthine is a degradation product of purines found in DNA.</p> Signup and view all the answers

<p>It is used to treat leukemia and Crohn's disease.</p> Signup and view all the answers

<p>Caffeine acts as a stimulant, enhancing alertness and reducing fatigue.</p> Signup and view all the answers

<p>Gout is the condition caused by uric acid crystals depositing in joints.</p> Signup and view all the answers

<p>Acyclovir is the most commonly used antiviral for Herpes infections.</p> Signup and view all the answers

<p>Azathioprine is used for organ transplantation and autoimmune diseases.</p> Signup and view all the answers

<p>Purines are key constituents of DNA and RNA, and act as hormones and neurotransmitters.</p> Signup and view all the answers

<p>Nucleosides consist of a purine base linked to a sugar, which is crucial for forming nucleotides that make up DNA and RNA.</p> Signup and view all the answers

<p>In purines, nucleophilic attacks occur at the carbon in the 6-membered ring, while both electrophilic and nucleophilic attacks happen at the 5-membered ring.</p> Signup and view all the answers

<p>The four tautomers of purine can interconvert, which affects base pairing in DNA and RNA, influencing genetic coding.</p> Signup and view all the answers

<p>Purines have specific functional groups that can donate or accept protons, allowing them to form hydrogen bonds with complementary pyrimidine bases.</p> Signup and view all the answers

<p>Adenine (A) corresponds to adenosine and guanine (G) corresponds to guanosine.</p> Signup and view all the answers

<p>The sugar-phosphate backbone provides structural integrity and protects the genetic information within nucleic acids.</p> Signup and view all the answers

<p>RNA is typically single-stranded and contains ribose sugar, while DNA is double-stranded and contains deoxyribose sugar.</p> Signup and view all the answers

<p>Fused rings refer to two or more cyclic structures that share common atoms, which can influence their chemical properties and reactivity.</p> Signup and view all the answers

<p>The stability of purines allows them to reliably store and transfer genetic information and energy within cells.</p> Signup and view all the answers

<p>Riboflavin is essential for energy metabolism and is a central component of the cofactors FAD and FMN.</p> Signup and view all the answers

<p>Tricyclic antidepressants typically have a three-ring structure that includes nitrogen atoms with various substituents.</p> Signup and view all the answers

<p>Benzodiazepines enhance the effect of the neurotransmitter GABA at the GABA-A receptor, leading to sedation.</p> Signup and view all the answers

<p>Phenothiazines are characterized by a sulfur atom in their structure and are classified based on the substituent on the nitrogen.</p> Signup and view all the answers

<p>FAD is reduced to FADH2 by accepting electrons and protons during metabolic reactions.</p> Signup and view all the answers

<p>The isoalloxazine ring is critical for the biochemical function of flavin coenzymes, facilitating electron transfer.</p> Signup and view all the answers

<p>FAD and FMN are both derived from riboflavin and serve as important cofactors in redox reactions.</p> Signup and view all the answers

<p>Chlorpromazine is noted for being the oldest typical antipsychotic and belongs to the phenothiazine class.</p> Signup and view all the answers

<p>Pteridine is a component of folic acid (vitamin B9), which is essential for producing healthy red blood cells and is particularly important during rapid cell division and growth.</p> Signup and view all the answers

<p>Pteridine serves as a precursor in the synthesis of pteroic acid, which is a component of folic acid, involved in several anti-cancer drugs.</p> Signup and view all the answers

<p>Pteridine has a bicyclic structure formed by a fused pyrimidine and pyrazine ring system, exhibiting a 10 π electron system which makes it aromatic.</p> Signup and view all the answers

<p>P-aminobenzoic acid (paba) combines with pteridine and glutamic acid to form folic acid, highlighting its importance in the synthesis process.</p> Signup and view all the answers

<p>Anti-cancer drugs use pteridine derivatives like methotrexate to inhibit folic acid metabolism, essential for cancer cell growth.</p> Signup and view all the answers