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Organic Chemistry (Chemistry for Changing Times, 11e) Chapter 9 Flashcards

9.1 Foundations and Definitions

  • Organic chemistry is defined as the chemistry of the compounds of carbon

  • Approximately what percentage of known compounds are classified as organic? Answer: ≈ 95%.

  • The most unique property of carbon is its ability to bond to carbon (catenation) and to other kinds of atoms. Answer: D.

  • An organic compound is best defined as: A) a compound containing carbon.

  • The first organic compound to be synthesized in a chemist’s laboratory was urea. Answer: C.

  • The first recorded synthesis of an organic compound in a scientific laboratory was by Friedrich Wöhler in 1828. Answer: C.

  • The element whose atoms have a unique ability to bond to each other and to other kinds of atoms is carbon (not sodium, sulfur, or nitrogen). Answer: B.

  • Carbon is almost always tetravalent (forms four bonds). Answer: D.

  • The unique aspect of a saturated hydrocarbon is that it must contain only single bonds (no multiple bonds). Answer: B.

  • The simplest alkane is methane (CH₄). Answer: C.

  • Petroleum jelly is a mixture of higher carbon number hydrocarbons (not low or moderate). Answer: C.

  • The formula CH₃CH₂CH₃ corresponds to propane. Answer: C.

  • A compound containing only carbon and hydrogen and with no double bonds is an alkane. Answer: A.

  • The formula CH₃CH₃ corresponds to ethane. Answer: B.

  • The formula CH₃CH₂CH₂CH₃ corresponds to butane. Answer: D.

  • How many different structural isomers are there for C₄H₁₀? Answer: 2.

  • How many different structural isomers for C₅H₁₂? Answer: 3.

  • How many structural isomers for C₆H₁₄? Answer: >4.

  • Not a reason for the great variety of organic molecules: carbon atoms can form more than four bonds (this statement is not true; carbon forms up to four bonds). Answer: B.

  • Alkanes are often called saturated hydrocarbons. Answer: B.

  • Compounds with the same number and kinds of atoms but with different structures are isomers. Answer: C.

  • CH₃CH₃ and CH₃CH₂CH₃ are isomers. Answer: D.

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9.2 Alkanes, Isomerism, and Nomenclature

  • Name the three-carbon alkane: propane. Formula:

    • Formula: C3H8

    • Name: propane.

  • The two-carbon alkane: ethane. Formula: C2H6.

  • The four-carbon alkane: butane. Formula: C4H{10}.

  • The general formula for alkanes (saturated, single bonds): CnH{2n+2}.

  • The general formula for cycloalkanes (ring, no double bonds): CnH{2n}.

  • Petroleum jelly: higher carbon number hydrocarbons (relative to methane, ethane).

  • The condensed structural formula comparisons (example):

    • Ethane: CH3CH3

    • Propane: CH3CH2CH_3

  • The concept of structural isomers: same molecular formula, different connectivity.

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9.3 Cycloalkanes and Ring Structures

  • Cyclopropane: formula C3H6.

  • Cyclohexane: formula C6H{12}.

  • Cyclopentane: formula C5H{10}.

  • General formula for cycloalkanes: CnH_{2n} (ring, no multiple bonds).

  • Propane, benzene, acetylene, and 2-butene are all hydrocarbons. Answer: D.

  • The general formula for a cycloalkane is discussed in. See above.

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9.4 Alkenes, Alkynes, and Aromatics

  • A saturated hydrocarbon contains only single bonds. Answer: B.

  • Alkanes are saturated; alkenes and alkynes are unsaturated (contain at least one multiple bond).

  • The general formula for alkenes (with one double bond) is CnH{2n}.

  • The general formula for alkynes (with one triple bond) is CnH{2n-2}.

  • The simplest alkene is ethene (ethylene): CH2=CH2.

  • The simplest alkyne is acetylene: C2H2.

  • Benzene (an aromatic hydrocarbon) has the formula C6H6.

  • Benzene’s ring structure and aromaticity are distinct from typical cyclic alkenes; it is not simply a cyclic diene.

  • Acetylene, ethylene, propane, and benzene are all hydrocarbons (but benzene is aromatic).

  • Important commercial compound: ethylene (ethylene, CH2=CH2).

  • Propyne (an alkyne) has formula C3H4.

  • Propyne and other alkynes are hydrocarbon compounds containing carbon–carbon triple bonds.

  • A cyclic hydrocarbon with six carbons and one double bond has formula C6H{10}.

  • A cyclic hydrocarbon with seven carbons and two double bonds has formula C7H{12} or C7H{10} depending on the exact structure; in the quiz, the listed answer corresponds to C7H{10}.

  • General formulas and specific examples for cycloalkenes and alkynes are included throughout.

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9.5 Benzene, Aromaticity, and Related Compounds

  • Benzene is an aromatic hydrocarbon with a ring of carbon atoms; it has unique stability and reactivity compared to typical alkenes.

  • The structure of benzene was proposed by Kekulé in 1865.

  • Aromatic compounds contain benzene rings or benzene-like properties.

  • Molecular formula for benzene: C6H6.

  • Substituted benzene and phenol: phenol is benzene with a hydroxyl group attached (C₆H₅OH).

  • The phrase “benzene-like” refers to aromatic stability and delocalized electrons; benzene does not behave like a typical cyclic alkene in its reactions.

  • True/False insight: benzene has a ring of carbon atoms and is aromatic; it does not necessarily undergo the same addition reactions as other unsaturated hydrocarbons.

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9.6 Chlorinated Hydrocarbons, CFCs, and Environmental Impact

  • Chlorinated hydrocarbons have been used as insecticides (DDT, PCBs) and solvents.

  • CFCs (chlorofluorocarbons) are typically gases or liquids with low boiling points; found in refrigerators and other applications.

  • On earth’s surface chlorofluorocarbons are relatively unreactive, but in the high-energy environment of the stratosphere they contribute to ozone depletion.

  • Phosgene (COCl₂) was produced from carbon tetrachloride (CCl₄) and used in warfare; such chemistry led to cessation of many uses of carbon tetrachloride.

  • Perfluorocarbons are hydrocarbons in which all hydrogen atoms are replaced by fluorine; used in various specialized applications.

  • General summary: environmental and health concerns drive restrictions on CFCs and chlorinated hydrocarbons; summarizing uses and drawbacks is covered in

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9.7 Functional Groups, General Formulas, and the Role of R

  • In organic chemistry, functional groups determine chemical properties; the symbol R stands for an alkyl group (a generic hydrocarbon chain). Answer: D.

  • Alcohols are characterized by the hydroxyl functional group, OH (or ROH when written as an alkyl alcohol). Answer: A.

  • Organic compounds are commonly classified by functional group rather than state, color, or odor. Answer: B.

  • The functional groups give compounds characteristic chemical and physical properties (e.g., reactivity, polarity, boiling point). Answer: C.

  • The condensed formula for methanol is CH3OH or, in some conventions, CH4O; commonly written as methanol with formula CH_3OH.

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9.8 Alcohols, Methanol, Ethanol, and Applications

  • Wood destructive distillation yields methanol as the primary component of the resulting liquid mixture. Answer: A.

  • Most methanol today is produced by the synthesis of carbon monoxide and hydrogen at high temperature and pressure: CO + 2H2 \rightarrow CH3OH (industrial methanol synthesis).

  • The intoxicating alcohol in beverages is ethanol. Answer: A.

  • A bottle of rum labelled 80 proof contains 40% ethanol by volume. Answer: B.

  • Distillation of fermented grain yields 95% ethanol; the corresponding proof is 190 (percent twice the percent by volume). Answer: C.

  • Excessive ingestion of ethanol can lead to physiological addiction, memory loss, and liver deterioration. Answer: D.

  • Ethanol acts as a mild depressant. Answer: B.

  • What is the percent alcohol by volume in a 36 proof beverage? Answer: 18%.

  • Fetal alcohol syndrome is caused by CH₃CH₂OH (ethanol). Answer: B.

  • Citronellol, C₁₀H₁₉OH, is an alcohol used in perfumery. Answer: A.

  • A homologous series of alcohols contains the same number of carbon atoms but varying numbers of hydroxyl groups? Answer: C (different carbon counts with same OH count is not the case; the correct statement is that each step adds a CH₂; see).

  • The main ingredient in most antifreezes is ethylene glycol. Answer: B.

  • Glycerol is an alcohol with three hydroxyl groups. Answer: C.

  • Compounds with a hydroxyl group attached directly to a benzene ring are called phenols, which are a subset of alcohol/phenol chemistry. Answer: D.

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9.9–9.10 Ethers, MTBE, and General Ether Chemistry

  • Ethers have two alkyl groups attached to an oxygen atom: R–O–R′. Answer: A.

  • MTBE (methyl tert-butyl ether) has been used as a gasoline additive; its structure is CH3OC(CH3)_3. Its general structure is an ether (ROR′).

  • Diethyl ether is a primary example of an ether with general structure R–O–R′ (ethyl groups).

  • The general formula ROR′ denotes an ether.

  • Diethyl ether is not used as a general anesthetic due to flammability, side effects, and availability of better anesthetics. Answer: D.

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9.11–9.12 Aldehydes, Ketones, Carboxylic Acids

  • Aldehydes and ketones share a common functional group: the carbonyl group, C=O. Answer: D.

  • The general formula for a ketone is RCO(R') or more explicitly RCOR'. Answer: C.

  • The simplest aldehyde is formaldehyde (CH₂O) and the simplest ketone is acetone (CH₃COCH₃). The quiz items include acetone and acetaldehyde as examples.

  • The carboxylic acid functional group is carboxyl, with the general formula RCOOH. Answer: D.

  • Vinegar is a solution of acetic acid in water. Answer: A.

  • Salts of carboxylic acids (e.g., sodium benzoate) are used in foods as preservatives. Answer: D.

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9.13–9.14 Esters, Amides, Amines, and Nucleophilic/Amine Chemistry

  • Esters are formed by the reaction of a carboxylic acid with an alcohol; general formula for an ester is RCOOR'. Answer: D.

  • Flavors isolated from foods are often esters. Answer: B.

  • An analgesic is a substance that acts as a pain reliever. Answer: D.

  • The compound formed by the reaction of ethanol with acetic acid is ethyl acetate. Answer: Ethyl acetate (structure: CH3COOCH2CH_3).

  • The compound formed by the reaction of ethanol with formic acid is ethyl formate. Answer: Ethyl formate (structure: HCOOCH2CH3).

  • Amines are derivatives of ammonia; the compound CH₃NH₂ is methylamine. Answer: A.

  • The tertiary amine (CH₃)₃N is trimethylamine. Answer: C.

  • When an amine dissolves in water, the solution is typically basic (pH > 7). Answer: C.

  • The simplest aromatic amine is aniline (C₆H₅NH₂). Answer: A.

  • The reaction between a carboxylic acid and an amine yields an amide. Answer: B.

  • Amino acids are multifunctional and contain both carboxyl and amine groups. They are the building blocks of proteins. Answer: A and D.

  • Amines, amino acids, and related structures are discussed in and connected to biological relevance (proteins, nucleic acids).

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9.15 Heterocyclic Compounds

  • Organic compounds with rings that contain atoms other than carbon are called heterocyclic compounds. Answer: B.

  • The non-carbon atom(s) commonly found in heterocyclic compounds include nitrogen, oxygen, and sulfur (and sometimes others). Answer: C.

  • Alkaloids (morphine, caffeine, nicotine, cocaine) are heterocyclic amines. Answer: A.

  • Compounds related to the heterocycles pyrimidine and purine are constituents of nucleic acids (DNA/RNA). Answer: B.

  • A question on identifying a heterocyclic compound among options was included in the True/False/Multiple-Choice section (correct option C in that item).

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True/False (Selected Concepts)

  • A compound with formula CnH{2n+2} is not an alkene; it’s an alkane. True.

  • A compound with at least one double bond is aromatic. False; not all compounds with a double bond are aromatic (aromaticity has specific criteria).

  • Benzene has a hydroxyl group attached to the ring? False; benzene is C₆H₆; phenol has a hydroxyl group attached to a benzene ring.

  • Chlorinated hydrocarbons have been used as insecticides. True.

  • A compound containing an -NH₂ group is an amine. True.

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Short Answer Questions (Selected Highlights)

  • Feature of carbon that explains why 95% of known compounds contain carbon: ability to form chains (carbon–carbon bonds) and branch into many structures.

  • Formula and name of the three-carbon alkane: C3H8; propane.

  • Formula and name of the two-carbon alkane: C2H6; ethane.

  • How many distinct isomers for C₄H₁₀? 2 isomers (n-butane and isobutane).

  • How many distinct isomers for C₅H₁₂? 3 isomers (n-pentane, isopentane, neopentane).

  • How many distinct isomers for C₆H₁₄? > 4 isomers (including multiple branched forms).

  • Oxidation states and typical reactivity patterns of alkanes vs alkenes/alkynes; alkanes are relatively inert and non-polar; alkenes/alkynes are more reactive due to π bonds (double/triple bonds).

  • The general rule: esters are formed from carboxylic acids and alcohols (condensation), with the general formula RCOOR'.

  • Important solvents and reagents: methanol, ethanol, acetone, etc., with emphasis on methanol production via synthesis gas (CO/H₂) and ethanol as beverage alcohol.

  • Common industrial and environmental notes: CFCs and ozone depletion; benzene toxicity concerns; phosgene history.

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Short Essay Topics (Study Prompts)

  • Comment on the statement that carbon can form an almost infinite number of molecules of various shapes, sizes and compositions. Recount how carbon’s tetravalence and ability to catenate enable vast diversity ().

  • Although benzene is a cyclic hydrocarbon with apparent alternating double bonds, it does not act as a typical cyclic alkene due to aromatic stabilization. Discuss using Kekulé’s structure and delocalized electrons ().

  • Draw a structure that is an isomer of benzene and explain isomerism and aromaticity concepts ().

  • Explain what a functional group is and why it simplifies the study of organic chemistry ().

  • Provide the structural formula of diethyl ether and explain its role as an ether ().

  • Compare aldehydes and ketones: define carbonyl group and give examples (e.g., acetaldehyde vs acetone) ().

  • Structurally relate aldehydes/ketones to carboxylic acids/esters; use general formulas to explain the similarity and difference ().

  • Identify two amines with formula C2H7N and name them; discuss amines’ basicity and pH behavior in water ().

  • List three isomers for formula C3H9N (amines) and discuss heterocyclic compounds in the context of biological molecules ().

  • Propose three isomers for formula C4H7N and discuss their structural diversity ().

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Key Formulas and Concepts (Summary)

  • Alkanes (saturated, single bonds): CnH{2n+2}

  • Cycloalkanes: ring hydrocarbons with formula CnH{2n}

  • Alkenes (one or more C=C): general formula CnH{2n}

  • Alkynes (one or more C≡C): general formula CnH{2n-2}

  • Aromatic hydrocarbon: benzene ring, formula C6H6; typical example of aromatic stability (electronic delocalization).

  • Benzene structure and Kekulé proposal (1865).

  • Functional groups and representations:

    • Alcohols: ROH; hydroxyl group (OH).

    • Ethers: ROR'; ether oxygen linking two carbon groups.

    • Emergent ethers example: MTBE CH3OC(CH3)3; diethyl ether CH3CH2OCH*2CH3.

    • Esters: RCOOR'; formed from carboxylic acids and alcohols; flavors.

    • Aldehydes and ketones: carbonyl group C=O; aldehyde RCHO; ketone RCOR'.

    • Carboxylic acids: RCOOH; carboxyl group; acetic acid in vinegar.

    • Amides: formed from carboxylic acids and amines (amide link).

    • Amines: derivatives of ammonia; RNH2, R2NH, R_3N (primary, secondary, tertiary); basic in water; pH>7.

    • Amino acids: contain carboxyl and amine groups; building blocks of proteins.

  • Nomenclature and symbols:

    • R denotes an alkyl group (alkyl substituent).

    • Condensed structural formulas illustrate connectivity (e.g., CH₃CH₃ for ethane; CH₃CH₂CH₃ for propane).

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Quick Reference: Example Compounds

  • Methane: CH_4 (alkane)

  • Ethane: CH3CH3 (alkane)

  • Propane: CH3CH2CH_3 (alkane)

  • Ethene (ethylene): CH2=CH2 (alkene)

  • Ethyne (acetylene): C2H2 (alkyne)

  • Benzene: C6H6 (aromatic)

  • Ethyl formate (formed from ethanol + formic acid): CH3CH2OCOH (ester)

  • Ethyl acetate (formed from ethanol + acetic acid): CH3COOCH2CH_3 (ester)

  • Methylamine: CH3NH2 (primary amine)

  • Trimethylamine: (CH*3)_3N (tertiary amine)

  • Methanol: CH_3OH (alcohol; solvent; industrial feedstock)

  • Ethanol: CH3CH2OH (drinking alcohol; biosynthesis via fermentation)

  • Formaldehyde: H_2CO (aldehyde)

  • Acetone: CH3COCH3 (ketone)

  • Acetic acid: CH_3COOH (carboxylic acid)

  • Glycerol: HOCH2CH(OH)CH2OH (triol)

  • MTBE: CH3OC(CH3)_3 (ether; gasoline additive)

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Connections to Broader Topics

  • Foundational principles: carbon’s tetravalence enables chain formation, branching, rings, and diverse functional groups; this underpins the vast diversity of organic chemistry ().

  • Real-world relevance: petroleum products, plastics, pharmaceuticals, fragrances, polymers, and environmental concerns (CFCs, chlorinated hydrocarbons, ozone depletion) highlighted in and.

  • Ethical and practical implications: limitations and health hazards of benzene and chlorinated solvents; regulation and safer alternatives are a key part of modern chemistry ().

  • Foundational tools: use of functional group concepts to predict reactivity, spectroscopy, and synthesis pathways; the concept of R groups () streamlines discussion of vast chemical space.

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Notes on Formulae and Notation (LaTeX)

  • General hydrocarbon formulas:

    • Alkanes: CnH{2n+2}

    • Cycloalkanes: CnH{2n}

    • Alkenes: CnH{2n}

    • Alkynes: CnH{2n-2}

  • Functional group notations:

    • Alcohols: ROH

    • Ethers: ROR'

    • Esters: RCOOR'

    • Aldehydes: RCHO

    • Ketones: RCOR'

    • Carboxylic acids: RCOOH

    • Amides: RCONH_2 (general form; discussed in )

  • Aromatic compounds: benzene ring, typical formula C6H6; aromatic stability arises from delocalized electrons.

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End of Chapter 9 Summary

  • This set of notes consolidates the major concepts, definitions, formulas, and representative examples from the transcript. Use the above as a compact reference to accompany the full MCQ/short-answer material for exam preparation.

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