Ethyl 3-oxobutanoate
Acetoacetic acid ethyl ester
Ethyl acetylacetate
3-Oxobutanoic acid ethyl ester
Ethyl acetoacetate is produced industrially by treatment of diketene with ethanol.
The preparation of ethyl acetoacetate is a classic laboratory procedure.[2] It is prepared via the Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.
Structure:
IUPAC Name: ethyl 3-oxobutanoate (ethyl acetoacetate)
Analysis: C6H10O3: MW = 130.14
The molecule contains an oxygen, and from the analysis, contains two double bonds, carbonyls or rings.
The mass spectrum displays a molecular ion and the base peak represents the formation of the acylium ion, indicating the presence of a methyl adjacent to a carbonyl. The presence of an m-45 peak strongly suggests the presence of an ethoxy group.
The 13C spectrum contains six peaks, indicating that all carbons are unique. The quartets at
14 and 24 represent relatively simple methyl groups; the triplets at 59 and 47 represent a CH2 groups bonded to mildly electronegative groups; the singlets at 207 and 172 are in the carbonyl region, and most likely a ketone or aldehyde ( 207) and an ester ( 172).The proton NMR shows evidence for an ethyl group and isolated CH2 and CH3 groups. The methylene of the ethyl group must be next to an electronegative atom (most likely oxygen) suggesting an -OCH2CH3 group. The isolated CH2 must also be flanked by mildly electronegative groups, and the isolated CH3 is in the region often observed for methyls adjacent to carbonyls.
The IR is consistent with a simple saturated hydrocarbon, possibly containing two carbonyls (based on the side peak at
1670 cm-1). The minor peak at 3400 cm-1 is too small to be an -OH.The simplest structure which is consistent with all of these data would be a dicarbonyl compound containing an ethoxy residue and a methyl ketone (based on the presence of the acylium ion in the MS).
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1H NMR
The proton NMR has a quartet coupled to a triplet, indicative of an ethyl group. The CH2 must be adjacent to an electron withdrawing group since it is shifted to
4.1. The two singlets at 2.2 and 3.2 suggest isolated CH2 and CH3 groups and the CH2 must be adjacent to one or more electronegative groups.
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13C NMR
13C NMR Assignments:
13C NMR Data: q-13.6; q-24.2; t-59.2; t-46.6; s-172.0; s-207.1
The 13C spectrum contains six peaks, indicating that all carbons are unique. The quartets at
14 and 24 represent relatively simple methyl groups; the triplets at 59 and 47 represent a CH2 groups bonded to mildly electronegative groups; the singlets at 207 and 172 are in the carbonyl region, and most likely a ketone or aldehyde ( 207) and an ester ( 172).
ethyl acetoacetate CH3COCH2COOCH2CH3
MASS SPECTROSCOPY
Mass Spectrum Fragments:
The mass spectrum consists of a molecular ion at 130, an m-15 peak at 115, which is consistent with loss of a CH3 group, an m-43 peak (loss of acylium), an m-45 peak (loss of CH3CH2O-), and a base peak at m-43(m/e = 43) which suggests the formation of an acylium ion (CH3-C
O). The spectrum is consistent with a molecule which can lose methyl or ethoxy radicals, or can undergo fragmentation to form the acylium radical cation................................
IR
3400-3200 cm-1: no OH peak (too small) 3100 cm-1: no significant peak, suggesting no unsaturated CH 2900 cm-1: strong peak suggesting saturated CH 2200 cm-1: no unsymmetrical triple bonds 1710 cm-1: strong carbonyl with a second peak at 1670 cm-1, suggesting a the possibility of two carbonyls 1600 cm-1: no significant peaks, suggesting no carbon-carbon double bonds
2D [1H,1H]-TOCSY
1D DEPT135
2D [1H,13C]-HSQC
2D [1H,13C]-HMBC
2D [1H,1H]-COSY
2D [1H,13C]-HMQC
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