Propose a mechanism for the reaction of pent-1-yne with

Problem 43SP Deduce the structure of each compound from the information given. All unknowns in this problem have molecular formula C8H12. a) Upon catalytic hydrogenation, unknown W gives cyclooctane. Ozonolysis of W, followed by reduction with dimethyl sulfide, gives octanedioic acid, HOOC—(CH2)6—COOH. Draw the structure of W. (b) Upon catalytic hydrogenation, unknown X gives cyclooctane. Ozonolysis of X, followed by reduction with dimethyl sulfide, gives two equivalents of butanedial, O CH—CH2CH2—CH O. Draw the structure of X. (c) Upon catalytic hydrogenation, unknown Y gives cyclooctane. Ozonolysis of Y, followed by reduction with dimethyl sulfide, gives a three-carbon dialdehyde and a five-carbon dialdehyde. Draw the structure of Y. *(d) Upon catalytic hydrogenation, unknown Z gives cis-bicyclo[4.2.0]octane. Ozonolysis of Z,followed by reduction with dimethyl sulfide, gives a cyclobutane with a three-carbon aldehyde (—CH2—CH2—CHO) group on C1 and a one-carbon aldehyde (—CHO) group on C2. Draw the structure of Z.

Problem 22P Disiamylborane adds only once to alkynes by virtue of its two bulky secondary isoamyl groups. Disiamylborane is prepared by the reaction of BH3–THF with an alkene. (a) Draw the structural formulas of the reagents and the products in the preparation of disiamylborane. (b) Explain why the reaction in part (a) goes only as far as the dialkylborane. Why is not formed?

Problem 2P For each molecular formula, draw all the isomeric alkynes, and give their IUPAC names. Circle the acetylenic hydrogen of each terminal alkyne. (a) C5H8 (three isomers) (b) C6H10 (seven isomers)

Problem 7P Show how you might synthesize the following compounds, using acetylene and any suitable alkyl halides as your starting materials. If the compound given cannot be synthesized by this method, explain why. (a) hex-1-yne (b) hex-2-yne (c) hex-3-yne (d) 4-methylhex-2-yne (e) 5-methylhex-2-yne (f) cyclodecyne

Problem 10P When 2,2-dibromo-1-phenylpropane is heated overnight in fused KOH at 200 °C, the major product is a foul-smelling compound of formula C9H8. Propose a structure for this product, and give a mechanism to account for its formation.

Problem 9P Show how you would synthesize 2-phenylhex-3-yn-2-ol, starting with acetophenone (PhCOCH3) and any other reagents you need. (“2-ol” means there is an OH group on C2.)

Show how you would synthesize each compound, beginning with acetylene and any necessary additional reagents. ________________ Equation Transcription: Text Transcription: H-CC-CH_{2}OH OH CH_{3}-CC-CH-CH_{2}CH_{2}CH_3 OH CH_{3}-C-CC-H Ph OH CH_{3}CH_{2}-C-CC-CH_{3} CH_{3}

Muscalure, the sex attractant of the common housefly, is cis-tricos-9-ene. Most syntheses of alkenes give the more stable trans isomer as the major product. Devise a synthesis of muscalure from acetylene and other compounds of your choice. Your synthesis must give specifically the cis isomer of muscalure. Equation Transcription: Text Transcription: CH_{3}(CH_{2})_7 C=C (CH_{2})_{12}CH_3

Give IUPAC names for the following compounds. Equation Transcription: Text Transcription: Ph CH_{3}-C{equiv}C-CH-CH_3 H_{3}C C=C CH_3 C{equiv}C-CH_{2}CH_{3} (CH3)3C-C{equiv}C-CH(CH_{3})CH_{2}CH_3 CH_{3}-CBr_{2}-C{equiv}C-CH_3 CH_3 CH_{3}-C{equiv}C-C-OH CH_{2}CH_{3} CH_{2}-C{equiv}C-CH_3

The application box in the margin of page 401 states, “The addition of an acetylide ion to a carbonyl group is used in the synthesis of ethchlorvynol, a drug used to cause drowsiness and induce sleep.” Show how you would accomplish this syn-thesis from acetylene and a carbonyl compound. Equation Transcription: Text Transcription: OH CH_{3}CH_{2}-C-C{equiv}CH CHCl

Give common names for the following compounds. (a) \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}_{2} \mathrm{CH}_{3}\) (b) \(\mathrm{Ph}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}\) (c) 3-methyloct-4-yne (d) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{CH}_{3}\) Equation Transcription: Text Transcription: CH_{3}-C{equiv}C-CH_{2}CH_{3} Ph-C{equiv}C-H (CH_{3})_{3}C-C{equiv}C-CH(CH_{3})CH_{2}CH_{3}

Oxidative cleavages can help to determine the positions of the triple bonds in alkynes. (a) An unknown alkyne undergoes oxidative cleavage to give adipic acid and two equiva- lents of acetic acid. Propose a structure for the alkyne. (b) An unknown alkyne undergoes oxidative cleavage to give the following triacid plus one equivalent of propionic acid. Propose a structure for the alkyne. Equation Transcription: Text Transcription: O_3 H_{2}O HOOC-(CH_{2})_{3}-COOH+2CH_{3}COOH O_3 H_{2}O COOH HOOC-(CH_{2})_{7}-CH-COOH+CH_{3}CH_{2}COOH

Problem 3P What reaction would acetylene likely undergo if it were kept at 1500 °C for too long?

Problem 11P When 2,2-dibromo-1-phenylpropane is heated overnight with sodium amide at 150 °C, the major product (after addition of water) is a different foul-smelling compound of formula C9H8 . Propose a structure for this product, and give a mechanism to account for its formation.

Problem 33SP Predict the products of reaction of pent-1-yne with the following reagents. (a) 1 equivalent of HCl (b) 2 equivalents of HCl (c) Excess H2, Ni (d) H2, Pd/BaSO4, quinolone (e) 1 equivalent of Br2 (f) 2 equivalents of Br2 (g) cold, dilute KMnO4 (h) warm, concd. KMnO4,NaOH (i) Na, liquid ammonia (j) NaNH2 (k) H2SO4/HgSO4,H2O (l) Sia2BH, then H2O2, -OH

Problem 1P (a) Count the elements of unsaturation in the three structures shown above (parsalmide, ethynyl estradiol, and dynemicin A). (b) Draw structural formulas of at least two alkynes of each molecular formula. (1) C6H10 (2) C8H12 (3) C7H8

Problem 12P Show how you would convert (a) oct-3-yne to cis-oct-3-ene (b) pent-2-yne to trans-pent-2-ene (c) cis-cyclodecene to trans-cyclodecene (d) but-1-yne to cis-hex-3-ene

Problem 14P In the addition of just 1 mole of bromine to 1 mole of hex-1-yne, should the hex-1-yne be added to a bromine solution or should the bromine be added to the hex-1-yne? Explain your answer.

Problem 13P The fragrance of (Z)-1-phenylhex-2-en-1-ol resembles that of roses, with a delicate citrus edge. Show how you would synthesize this compound from benzaldehyde (PhCHO) and any other reagents you need.

Problem 15P Propose a mechanism for the entire reaction of pent-1-yne with 2 moles of HBr. Show why Markovnikov’s rule should be observed in both the first and second additions of HBr.

Predict the products formed when \(\mathrm{CH}_{3} \mathrm{CH}_{2}-\mathrm{C} \equiv \mathrm{C}:^{-} \mathrm{Na}^{+}\) reacts with the following compounds. (a) ethyl bromide (b) tert-butyl bromide (c) formaldehyde (d) cyclohexanone (e) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CHO}\) (f) cyclohexanol (g) butan-2-one, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COCH}_{3}\) Equation Transcription: Text Transcription: CH_{3}CH_{2}-CC:^{-}Na^+ CH_{3}CH_{2}CH_{2}CHO CH_{3}CH_{2}COCH_{3}

Show how you would accomplish the following synthetic transformations. Show all intermediates. (a) 2,2-dibromobutane ? but- 1-yne (b) 2,2-dibromobutane ? but 2-yne (c) but- 1-yne ? oct-3-yne (d) trans-hex-2-ene ? hex-2-yne (e) 2,2-dibromohexane ? hex-1-yne (f) cyclodecyne ? cis-cyclodecene (g) cyclodecyne ? trans-cyclodecene (h) hex-1-yne? hexan-2-one, \(\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) (i) hex-1-yne ? hexanal, \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CHO}\) (j) trans-hex-2-ene ? cis-hex-2-ene Equation Transcription: Text Transcription: CH_{3}COCH_{2}CH_{2}CH_{2}CH_{3} CH_{3}(CH_{2})_{4}CHO

Show how you would synthesize the following compounds from acetylene and any other needed reagents: a) 6-phenylhex-1-en-4-yne (b) cis-1-phenylpent-2-ene (c) trans-1-phenylpent-2-en Equation Transcription: Text Transcription: CH_{2}Ph OH OH CH_{2}CH_{3}

Problem 19P When pent-2-yne reacts with mercuric sulfate in dilute sulfuric acid, the product is a mixture of two ketones. Give the structures of these products, and use mechanisms to show how they are formed.

Problem 20P The hydroboration–oxidation of internal alkynes produces ketones. (a) When hydroboration–oxidation is applied to but-2-yne, a single pure product is obtained. Determine the structure of this product, and show the intermediates in its formation. (b) When hydroboration–oxidation is applied to pent-2-yne, two products are obtained. Show why a mixture of products should be expected with any unsymmetrical internal alkyne.

For each compound, give the product(s) expected from (1) \(\mathrm{HgSO}_{4} / \mathrm{H}_{2} \mathrm{SO}_{4}\)-catalyzed hydration and (2) hydroboration–oxidation. (a) hex-1-yne (b) hex-2-yne (c) hex-3-yne (d) cyclodecyne Equation Transcription: Text Transcription: HgSO_{4}/H2SO_{4}

The following functional-group interchange is a useful synthesis of aldehydes. (a) What reagents were used in this chapter for this transformation? Give an example to illustrate this method. (b) This functional-group interchange can also be accomplished using the following sequence. Propose mechanisms for these steps. (c) Explain why a nucleophilic reagent such as ethoxide adds to an alkyne more easily than it adds to an alkene. Equation Transcription: Text Transcription: R-C{equiv}C-H R-CH_{2}C-H R-C{equiv}C-H NaOCH_{2}CH_{3} CH_{3}CH_{2}OH C=C OCH_{2}CH_{3} H_{3}O^+ R-CH_{2}-C-H

Using any necessary inorganic reagents, show how you would convert acetylene and isobutyl bromide to (a) meso-2,7-dimethyloctane-4,5-diol, \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}\) (b) \(\pm\)-2,7-dimethyloctane -diol Equation Transcription: Text Transcription: (CH_{3})_{2}CHCH_{2}CH(OH)CH(OH)CH_{2}CH(CH_{3})_{2} (+/-)

Show how you would convert the following starting materials into the target compound. You may use any additional reagents you need. Equation Transcription: Text Transcription: CH_{2}Br HC{equiv}CH C{equiv}C

Predict the major product(s) of the following reactions: (a) phenylacetylene + 2 HBr (b) hex-1-yne + 2 HCl (c) cyclooctyne + 2 HBr *(d) hex-2-yne + 2 HCl Equation Transcription: Text Transcription: 2 HBr 2 HCl 2 HBr 2 HCl

Problem 17P Propose a mechanism for the reaction of pent-1-yne with HBr in the presence of peroxides. Show why anti-Markovnikov orientation results.

Problem 18P Show how hex-1-yne might be converted to (a) 1,2-dichlorohex-1-ene (b) 1-bromohex-1-ene (c) 2-bromohex-1-ene (d) 1,1,2,2-tetrabromohexane (e) 2-bromohexane (f) 2,2-dibromohexane

Show how you would synthesize the following compounds, starting with acetylene and any compounds containing no more than four carbon atoms. (a) hex-1-yne (b) hex-2-yne (c) cis-hex-2-ene (d) trans-hcx-2-cne (e) 1,1 -dibromohexane (f) 2,2 -dibromohexane (g) pentanal, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CHO}\) (h) pentan-2-one, \(\mathrm{CH}_{3}-\mathrm{CO}-\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) (i) ()-3,4-dibromohexane (j) meso-butan- 2,3 -diol (k) 2-methylhex-3-yn-2-ol Equation Transcription: Text Transcription: CH_{3}CH_{2}CH_{2}CH_{2}CHO CH_{3}-CO-CH_{2}CH_{2}CH_{3}

When treated with hydrogen and a platinum catalyst, an unknown compound X absorbs 5 equivalents of hydrogen to given-butylcyclohexane. Treatment of X with an excess of ozone, followed by dimethyl sulfide and water, gives the following products: Propose a structure for the unknown compound X. Is there any uncertainty in your structure? Equation Transcription: Text Transcription: H-C-CH-CH_{2}-C-C-H H-C-C-H H-C-C-OH H-C-OH

When compound Z is treated with ozone, followed by dimethyl sulfide and washing with water, the products are formic acid, 3-oxobutanoic acid, and hexanal. Propose a structure for compound Z. What uncertainty is there in the structure you have proposed? Equation Transcription: Text Transcription: O_{3} (CH_{3})_{2}S, H_{2}O H-C-OH CH_{3}-C-CH_{2}-C-OH CH_{3}(CH_{2})_{4}-C-H

Problem 30SP Using hex-1-ene as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.) (a) 1,2-dibromohexane (b) hex-1-yne (c) 2,2-dibromohexane (d) hex-2-yne (e) hexan-2-one (f) hexanal (g) pentanoic acid (h) pentanal (i) undec-6-yn-5-ol

Problem 23P Predict the product(s) you would expect from treatment of each compound with (1) dilute, neutral kMnO4and (2) warm, basic KMnO4 then dilute acid. (a) hex-1-yne (b) hex-2-yne (c)hex-3-yne (d) 2-methylhex-3-yne (e) cyclodecyne

Problem 4P The boiling points of hex-1-ene (64 °C) and hex-1-yne (71 °C) are sufficiently close that it is difficult to achieve a clean separation by distillation. Show how you might use the acidity of hex-1-yne to remove the last trace of it from a sample of hex-1-ene.

Predict the products of the following acid–base reactions, or indicate if no significant reaction would take place. (a) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+\mathrm{NaNH}_{2}\) (b) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+\mathrm{CH}_{3} \mathrm{Li}\) (c) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+\mathrm{NaOCH}_{3}\) (d) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+\mathrm{NaOH}\) (e) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}:^{-} \mathrm{Na}^{+}+\mathrm{CH}_{3} \mathrm{OH}\) (f) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}:^{-} \mathrm{Na}^{+}+\mathrm{H}_{2} \mathrm{O}\) (g) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}:^{-} \mathrm{Na}^{+}+\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}\) (h) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}+\mathrm{NaNH}_{2}\) (i) \(\mathrm{CH}_{3} \mathrm{OH}+\mathrm{NaNH}_{2}\) Equation Transcription: Text Transcription: H-C{equiv}C-H+NaNH_2 H-C{equiv}C-H+CH_{3}Li H-C{equiv}C-H+NaOCH_3 H-C{equiv}C-H+NaOH H-C{equiv}C:^{-} Na^{+}+CH_{3}OH H-C{equiv}C:^{-} Na^{+}+H_{2}O H-C{equiv}C:^{-} Na^{+}+H_{2}C=CH_2 H_{2}C=CH_{2}+NaNH_2 CH_{3}OH+NaNH_2

Problem 6P Show the reagents and intermediates involved in the other order of synthesis of dec-3-yne, by adding the ethyl group first and the hexyl group last.

Develop syntheses for the following compounds, using acetylene and compounds containing no more than four carbon atoms as your organic starting materials. (a) 3-methylnon-4-yn-3-ol (“3-ol” means there is an OH group on C3.) (b) cis-1-ethyl-2-methylcyclopropane Equation Transcription: Text Transcription: OH C3 CH_{3}CH_2 CH_{2}CH_{2}CH_3

Using cyclooctyne as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.) (a) cis-cyclooctene (b) cyclooctane (c) trans-1,2-dibromocyclooctane (d) cyclooctanone (e) 1,1-dibromocyclooctane (f) 3-bromocyclooctene (g) cyclooctane-1,2-dione Equation Transcription: Text Transcription: HO OH

Problem 27SP Write structural formulas for the following compounds (includes both old- and new-style names). (a) 2-octyne (b) ethylisopentylacetylene (c) ethynylbenzene (d) cyclohexylacetylene (e) 5-methyl-3-octyne (f) trans-3,5-dibromocyclodecyne (g) 5,5-dibromo-4-phenylcyclooct-1-yne (h) (E)-6-ethyloct-2-en-4-yne (i) 1,4-heptadiyne (j) vinylacetylene (k) (S)-3-methyl-1-penten-4-yne