Aldol condensation: A simple teaching model for organic laboratory<\/h1>\n

link<\/p>\n

http:\/\/pubs.acs.org\/doi\/abs\/10.1021\/ed055p540<\/a><\/p>\n

To synthesize trans-dibenzalacetone from acetone and benzaldehyde using NaOH as the catalytic base in a 1:1 water\/ethanol solvent<\/p>\n

Procedure<\/p>\n

Prepare a 0.5M NaOH (20 mmol) solution in 40 mL of distilled water and prepare a 1M solution of benzaldehyde (40 mmol) in 40 mL of ethanol. Mix the two solutions throughly. Add 0.8 g (1.1 mL, 15 mmol) of acetone to the reaction mixture and stir for 30 minutes. Recover the product by suction filtration using a Buchner funnel.<\/p>\n

Amount: 3.044 g
\nAppearance: Bright yellow crystals
\nMelting Point: 103-104\u00b0C (lit mp 113\u00b0C)<\/p>\n

Purity: Very pure sample of trans-dibenzalacetone<\/p>\n

This procedure produced pure trans-dibenzalacetone without having to recrystallize. The two characteristic doublets of trans-dibenzalacetone had coupling constants of 16.25Hz (located at 7.7ppm) and 15.5Hz (located at 7.1ppm). These coupling constants of near 15Hz indicates that the trans product was recovered.<\/p>\n

The limiting reagent was the acetone (0.8 g, 15 mmol) and the precent yield of this reaction was 87%. An excess of benzaldehyde (1.33 equivalent) was used and the benzaldehyde was dissolved into the ethanol prior to being introduced into the reaction mixture.<\/p>\n

3.044 g of pure trans-dibenzalacetone was produced in a yield of 87%<\/p>\n

Mech-Dibenzalacetone is readily prepared by the crossed Aldol condensation between benzaldehyde and acetone under alkaline conditions.\u00a0Acetone is a carbonyl compound that contains alpha hydrogens. Therefore, it can\u00a0participate in the various condensation reactions that involve removal of an alpha^{\u00a0<\/sup>hydrogen. Benzaldehyde, on the other hand, does NOT contain any alpha\u00a0hydrogens. The following sequence of reactions indicates the pathway for the formation of dibenzalacetone.<\/p>\n}

 <\/p>\n

<\/p>\n

The carbanion produced by this step reacts with the more active benzaldehyde rather than with a second molecule of acetone. Thus, the next step becomes:<\/p>\n

 <\/p>\n

<\/p>\n

Because a 2:1 molar ratio of benzaldehyde is used, the reaction continues.<\/p>\n

<\/p>\n

The overall balanced equation is:<\/p>\n

<\/p>\n","protected":false},"excerpt":{"rendered":"

Aldol condensation: A simple teaching model for organic laboratory link http:\/\/pubs.acs.org\/doi\/abs\/10.1021\/ed055p540 To synthesize trans-dibenzalacetone from acetone and benzaldehyde using NaOH as the catalytic base in a 1:1 water\/ethanol solvent Procedure Prepare a 0.5M NaOH (20 mmol) solution in 40 mL of distilled water and prepare a 1M solution of benzaldehyde (40 mmol) in 40 mL… Continue reading Aldol condensation: A simple teaching model for organic laboratory<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts\/65"}],"collection":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/comments?post=65"}],"version-history":[{"count":2,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts\/65\/revisions"}],"predecessor-version":[{"id":149,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts\/65\/revisions\/149"}],"wp:attachment":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/media?parent=65"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/categories?post=65"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/tags?post=65"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}