{"id":228006,"date":"2025-06-06T16:54:39","date_gmt":"2025-06-06T16:54:39","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=228006"},"modified":"2025-06-06T16:54:41","modified_gmt":"2025-06-06T16:54:41","slug":"predict-the-major-organic-product-for-the-following-reaction-sequence-1-nacch-thf-2-h2o-h2so4-hgso4-3-hac_-br-4-naccch2ch3-dmso-5-h2-pd-c","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/06\/predict-the-major-organic-product-for-the-following-reaction-sequence-1-nacch-thf-2-h2o-h2so4-hgso4-3-hac_-br-4-naccch2ch3-dmso-5-h2-pd-c\/","title":{"rendered":"Predict the major organic product for the following reaction sequence: 1) NaCCH, THF 2) H2O, H2SO4, HgSO4 3) HaC_ Br 4) NaCCCH2CH3, DMSO 5) H2, Pd\/C"},"content":{"rendered":"\n

Predict the major organic product for the following reaction sequence: 1) NaCCH, THF 2) H2O, H2SO4, HgSO4 3) HaC_ Br 4) NaCCCH2CH3, DMSO 5) H2, Pd\/C<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

Correct Answer: Pentan-2-one (CH\u2083CH\u2082COCH\u2082CH\u2083)<\/strong><\/h3>\n\n\n\n
\n\n\n\n

Step-by-Step Explanation (300 words):<\/strong><\/h3>\n\n\n\n

We are given a multistep organic synthesis starting from 1-bromobutane<\/strong>. Let\u2019s analyze each step of the reaction sequence.<\/p>\n\n\n\n

\n\n\n\n

Step 1: NaC\u2261CH (sodium acetylide), THF<\/strong><\/h4>\n\n\n\n

This is a nucleophilic substitution reaction. Sodium acetylide (NaC\u2261CH<\/strong>) is a strong nucleophile that reacts with the alkyl halide<\/strong> (1-bromobutane) in an S<sub>N<\/sub>2<\/strong> mechanism. The acetylide attacks the electrophilic carbon bonded to Br, displacing the Br\u207b ion.<\/p>\n\n\n\n

Result:<\/strong>
CH\u2083CH\u2082CH\u2082C\u2261CH (1-pentyne)<\/p>\n\n\n\n

\n\n\n\n

Step 2: H\u2082O, H\u2082SO\u2084, HgSO\u2084<\/strong><\/h4>\n\n\n\n

This is acid-catalyzed hydration<\/strong> of the terminal alkyne (1-pentyne)<\/strong> using Hg\u00b2\u207a<\/strong> as a catalyst. This reaction follows Markovnikov\u2019s rule<\/strong>, adding -OH to the more substituted carbon of the triple bond. The initial enol tautomerizes into a ketone<\/strong>.<\/p>\n\n\n\n

Result:<\/strong>
CH\u2083CH\u2082COCH\u2083 (2-pentanone)<\/p>\n\n\n\n

\n\n\n\n

Step 3: NaC\u2261CCH\u2082CH\u2083 (sodium 1-butyne), DMSO<\/strong><\/h4>\n\n\n\n

This step involves the reaction of the carbonyl compound (2-pentanone) with a terminal alkyne anion. The terminal alkyne is deprotonated to form a nucleophilic acetylide anion, which attacks the electrophilic carbonyl carbon of 2-pentanone.<\/p>\n\n\n\n

This yields a tertiary alcohol<\/strong> with an alkyne side chain:<\/p>\n\n\n\n

Result:<\/strong>
CH\u2083CH\u2082C(OH)(CH\u2083)CH\u2082C\u2261CH<\/p>\n\n\n\n

\n\n\n\n

Step 4: H\u2082, Pd\/C<\/strong><\/h4>\n\n\n\n

This is hydrogenation<\/strong> over a palladium catalyst. It fully saturates the alkyne and the alkene (if any), converting the triple bond to a single bond.<\/p>\n\n\n\n

Final Product:<\/strong>
CH\u2083CH\u2082C(OH)(CH\u2083)CH\u2082CH\u2082CH\u2083
This is a tertiary alcohol<\/strong>: 3-hexanol.<\/p>\n\n\n\n

\n\n\n\n

Correction<\/strong><\/h3>\n\n\n\n

However, the correct sequence is slightly different than described above.<\/p>\n\n\n\n

Upon closer inspection of the image, the sequence is:<\/p>\n\n\n\n

    \n
  1. SN2 reaction: CH\u2083CH\u2082CH\u2082Br + NaC\u2261CH \u2192 CH\u2083CH\u2082CH\u2082C\u2261CH<\/li>\n\n\n\n
  2. Hydration of alkyne \u2192 CH\u2083CH\u2082COCH\u2083 (2-pentanone)<\/li>\n\n\n\n
  3. Nucleophilic attack on carbonyl with NaC\u2261CCH\u2082CH\u2083 \u2192 CH\u2083CH\u2082C(OH)(CH\u2083)CH\u2082C\u2261CH<\/li>\n\n\n\n
  4. Hydrogenation of alkyne \u2192 CH\u2083CH\u2082C(OH)(CH\u2083)CH\u2082CH\u2082CH\u2083<\/strong><\/li>\n<\/ol>\n\n\n\n

    \u2705 Final Answer: 3-Hexanol (CH\u2083CH\u2082CH(OH)CH\u2082CH\u2082CH\u2083)<\/strong><\/h3>\n\n\n\n
    \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

    Predict the major organic product for the following reaction sequence: 1) NaCCH, THF 2) H2O, H2SO4, HgSO4 3) HaC_ Br 4) NaCCCH2CH3, DMSO 5) H2, Pd\/C The Correct Answer and Explanation is: Correct Answer: Pentan-2-one (CH\u2083CH\u2082COCH\u2082CH\u2083) Step-by-Step Explanation (300 words): We are given a multistep organic synthesis starting from 1-bromobutane. Let\u2019s analyze each step of […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-228006","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/228006","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=228006"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/228006\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=228006"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=228006"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=228006"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}