Organic I Review Workbook: The Toolbox All-Star Molecules

Organic I Review Workbook The Toolboxall Star Molecules Should

Review Basic Geometries/Hybridization/Bonding Questions: a) Does the electronegativity of a carbon atom increase or decrease with increasing p- character? Use acetylene and ethylene as examples to help explain your reasoning. Still stuck? Table 4.1 may provide even more assistance. b) What is more nucleophilic, a carbon-carbon π bond or σ bond? c) What is lower in energy, the π orbital or σ orbital of a C=C bond? d) Are the orbitals described in part c) representative of electrophiles or nucleophiles? e) A lone pair must be in what kind of orbital(s) in order to participate in resonance/conjugation? s, p, sp, sp2 or sp3. Choose all that apply.

Functional Group Recognition / Functional Group Transformation (A+B = C) Alkene, Aldehyde, Glycol, Alkyl halide, Carboxylic Acid, Ketone, Alcohol (alkyl vs aryl), Ether, Nitrile, Amine (1°, 2°, 3°), Ester, Sulfide, Alkyne, Epoxide, Thiol, Amide (1°, 2°, 3°), Enol Questions: a) Which functional groups above contain the carbonyl/acyl group? b) Is the carbonyl/acyl carbon of a ketone electrophilic or nucleophilic? c) All things being equal, which functional group is the most Bronsted acidic (not including the carboxylic acid)? d) The transformation of a functional group can be described as a single functional group starting material (A) being added to a selective environment (B) to generate a new functional group (C). Basically, A+B = C. With this in mind, which functional group(s) was (were) NOT synthesized in the first semester? e) Which functional group has the most electron rich sp2 oxygen? Provide a structure to support your answer. Resonance comes in handy here… f) Is a Bronsted acid a nucleophile or electrophile? A Bronsted base? g) How many atoms are sp2 hybridized in acetic acid? h) How many atoms are sp2 hybridized in phenol? i) How many atoms are sp2 hybridized in heroin?

Structural Relationships and Language - Review all terms and definitions for the following: ï‚· Constitutional isomers vs Conformation isomers vs Configurational Isomers ï‚· Stereoisomers (Diastereomers, Enantiomers) ï‚· Optical Activity, Racemic, Meso ï‚· Determination of Absolute Configuration Questions: a) What term can be used to describe the isomeric relationship above? b) Each molecule above can be described as a vicinal diol. What is a more common and more utilized term for describing a vicinal diol? This functional group will play a vital role as a protection group in Organic 2. (Nothing ever goes away completely). c) Assign the configurations for each chiral center? d) Are both molecules optically active? Explain. e) Provide two different synthetic routes to produce each molecule and determine if a racemic mixture is generated in each case (i.e., you need to come up with 4 reactions in total). If a racemic mixture is not obtained, explain why?

Past, Present and Future: Putting it all together! The reaction below occurs in the presence of H2, Ni or sodium borohydride (NaBH4). A recognition of possibilities and a process of elimination can lead you to the correct answer(s) and expand your knowledge. a) Is the final product chiral? b) What is the index of hydrogen deficiency (IHD) for the starting material? c) Considering the mechanism, provide two different line angle structures (with stereochemistry) for a starting material that agree with the product data. d) What is the isomeric relationship between these two possible starting materials?

Resonance….Resonance….Resonance – Allylic and Benzylic…Practice drawing resonance structures for these systems using line angle representations only. Use systems with a minimum of 4 carbons in their chain or ring.

Bronsted Acids & Bases! Understand the significance of pKa, Ka, etc. a) True/False. Increasing Ka represents increasing acidity. b) When does the pH = pKa? ï‚· Review pKa tables and understand how “The Protocol†impacts acidity and basicity to develop a “feel†for values. For example, rank molecules such as phenol, benzoic acid, acetic acid, acetone, acetaldehyde, acetylene, acetonitrile, ethanol, lactic acid, nitromethane, pyruvic acid, carbonic acid, and ammonium chloride in order of decreasing pKa. Question: Benzoic acid has a lower pKa than acetic acid. Which factors from “The Protocol†explain this difference? Explain. Exercise 6.2: Provide the conjugate acids/bases for reactions like acetylene + LDA and acetic acid + diisopropylamine and determine the favored direction. Exercise 6.3: Consider the structure of ciprofloxacin hydrochloride mono hydrate, a broad-spectrum antibiotic. Answer questions about its form and reactivity, understanding that pharmaceuticals are often administered in protonated acid forms.

General Reactivity Trends: Focus on carbon intermediates like carbocations and radicals. Remember the importance of Bronsted acid/base reactions. Lone pairs on atoms adjacent to p-orbitals are sp2 hybridized. Recognize whether resonance effects or inductive effects dominate in predicting reactivity. Use these guidelines to inform reaction predictions and mechanisms.

“THE TOOLBOX†– Key reagents in Organic 1 for functional group transformations include halogenators, acids, oxidizers, reducers, solvents, substitution systems, carbon sources, and other reagents. Master recognizing these molecules, their structures, and their roles in reactions, especially “STAR MOLECULES”. Practice regioselectivity and stereoselectivity in reactions, including hydration, hydrolysis, and multi-step synthesis, using conditions from the “Chemical Stockroom”. Understanding these reactions and mechanisms prepares you for complex synthesis problems and retrosynthetic analysis. Pay attention to restrictions, conditions, and pathways that lead to desired products, and practice retrosynthesis by deconstructing complex molecules into simpler starting materials with proper conditions and mechanisms. Also focus on multistep synthesis and ring formation, interpreting reaction pathways and stereochemistry. Lastly, develop your skills in organic diagnostics, including recognizing when data or analysis are incorrect, and review mechanisms involving proton transfers, addition, elimination, substitution, and rearrangements, emphasizing electron flow and formal charges. This comprehensive review aims to solidify your foundational knowledge for Organic Chemistry II, enhancing your ability to recognize functional groups, predict transformations, and understand reaction mechanisms deeply.

Paper For Above instruction

Organic chemistry is a complex and interconnected discipline that requires mastery of functional groups, reaction mechanisms, stereochemistry, and the ability to connect concepts across different reactions and pathways. The goal of this review is to synthesize key concepts, focusing on the organization and emphasis on "Star Molecules" that serve as essential reagents and functional groups throughout organic chemistry coursework. These molecules, known by common names, IUPAC nomenclature, line structures, and even personal associations like favorite flavors or songs, form the foundational vocabulary needed for fluency in organic reactions and mechanisms.

Understanding molecular geometries, hybridization, and bonding is fundamental. For example, the electronegativity change in carbon with increasing p-character influences the reactivity and stability of molecules like acetylene and ethylene. Acetylene, with its sp hybridized carbons, exhibits a higher p-character, leading to greater electronegativity and a more linear geometry, while ethylene with sp2 carbons has a somewhat less electronegative carbon. These differences in hybridization influence the energy levels of molecular orbitals; the π orbital of C=C is lower in energy than the σ orbital, and these orbitals are typically associated with nucleophilic or electrophilic behavior in reactions. Lone pairs in p or sp2 orbitals are essential for resonance and conjugation, affecting the stability and reactivity of functional groups such as carbonyls and amines.

Recognizing functional groups—alkenes, aldehydes, ketones, alcohols, acids, esters, and amines—is critical for understanding possible transformations (A+B=C). The carbonyl group's electrophilicity, for example, underpins many nucleophilic addition reactions. Functional groups such as phenols contain electron-rich oxygen atoms capable of resonance stabilization. Acidic behavior, influenced by structures and resonance, is fundamental in determining reactivity, with pKa values offering a quantitative measure. Therefore, recognizing the influence of resonance and inductive effects helps in ranking acidity and predicting reaction pathways.

Stereochemistry and structural relationships, including isomers and configurational options, are core concepts. Enantiomers and diastereomers can be identified and characterized by optical activity, with absolute configuration being assigned through systematic stereochemical methods. Synthetic routes to compounds involve strategic use of reagents, with awareness of racemization potential and stereoselectivity. Furthermore, advanced topics include multistep synthesis, retrosynthesis, and ring formation, which require careful planning and understanding of reaction mechanisms and conditions, especially those available in the “Chemical Stockroom”.

Resonance structures, especially in allylic and benzylic systems, enhance understanding of radical and ionic stability, which influences reaction outcomes. Recognizing the mechanisms—addition, elimination, substitution, and rearrangement—and classifying reactions accordingly enables chemists to design and analyze synthetic pathways effectively. Proton transfer reactions, vital for many steps, demonstrate the importance of acidity and basicity, with pKa guiding predictions of the direction of equilibrium.

In summary, this comprehensive review consolidates the essential knowledge necessary for success in Organic Chemistry II. Mastery involves recognizing functional groups, understanding mechanisms, designing syntheses, and analyzing reactivity trends. The emphasis on "Star Molecules," reaction pathways, and strategic planning will prepare students not only for exams but also for practical problem-solving in organic synthesis and applied chemistry contexts.

References

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