The Chemistry of the 2-Imidazolines and Imidazolidines.

Ferm, Robert J.; Riebsomer, J. L.

doi:10.1021/cr60170a002

Cited by 94 publications

(43 citation statements)

References 49 publications

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“…This is an example of the usual method of synthesis of 2-substituted 2-imidazolines, namely the cyclization reaction of ethylenediamine with a carboxylic acid or rather one of its derivatives. 3 The reaction sequence in Scheme 1 is rather unsuitable for our labelling purpose (too many steps) but the approach in general is convenient to the extent that [ 11 C]carboxylic acids are normally easy to make in good yields from [ 11 C]carbon dioxide and the appropriate Grignard reagent. Its disadvantage lies in the fact that the radioactivity introduction is to be followed by at least one chemical step, but this drawback looks inevitable for this type of molecule in any case.…”

Section: Resultsmentioning

confidence: 99%

Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐¹¹C] imidazole: the I₂ imidazoline receptor ligand [¹¹C] benazoline

Roeda

Hinnen

Dollé

2003

Labelled Comp Radiopharmac

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SummaryBenazoline (2-naphthalen-2-yl-4,5-dihydro-1H-imidazole) is a selective highaffinity ligand for the imidazoline I 2 receptor. This compound was labelled with carbon-11 (T 1=2 =20.4 min) at the number two carbon atom of its 2-imidazoline ring. Cyclotron-produced [11 C]carbon dioxide reacted with 2-naphthylmagnesium bromide to give 2-[carboxyl-11 C]naphthoic acid in 60% radiochemical yield. The latter was heated with a mixture of ethylenediamine and its dihydrochloride at 3008C to give [ 11 C]benazoline in 16% overall yield, relative to [ 11 C]carbon dioxide and with a specific radioactivity of 54 GBq/ mmol, decay corrected for end of irradiation. The procedure requires about 45 min from end of cyclotron irradiation. This method should be extendable to other imidazolines.

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Section: Resultsmentioning

confidence: 99%

Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐¹¹C] imidazole: the I₂ imidazoline receptor ligand [¹¹C] benazoline

Roeda

Hinnen

Dollé

2003

Labelled Comp Radiopharmac

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“…Fatty imidazolines and fatty amides are used widely or are precursors for surface-active compounds (1,2). Industrially, imidazolines are prepared in a thermal reaction between diethylene triamine (DETA) with fatty acids, triglycerides, or methyl esters of fatty acids (3,4).…”

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confidence: 99%

Thermal reactions of fatty acids with diethylene triamine

Herrington

1997

J Americ Oil Chem Soc

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The relative reactivities of the primary and secondary amino groups of diethylene triamine with fatty acids depend on the thermal reaction conditions. Without solvents, the primary amines are more reactive than the secondary amine for steric reasons, and the reaction results mainly in the 1,3-diamide. However, in dilute solution, the secondary amine shows higher reactivity than the primary amines, and the reaction proceeds probably by way of the 1,2-diamide, which forms imidazolines under much milder conditions than from the 1,3-diamide. The hydrolysis of imidazoline to the 1,2-diamide as the major product confirmed the higher reactivity of the secondary amine. JAOCS 74, 61-64 (1997).Fatty imidazolines and fatty amides are used widely or are precursors for surface-active compounds (1,2). Industrially, imidazolines are prepared in a thermal reaction between diethylene triamine (DETA) with fatty acids, triglycerides, or methyl esters of fatty acids (3,4). However, the literature of this fatty acid-DETA reaction is contradictory. It is claimed that DETA reacts with fatty acids to form fatty acid monoamides 3 (Scheme 1), which can cyclize to imidazoline compounds 4 that contain a free primary amine group (5). Even though no structural evidence is given, the preparation of compounds 3 and 4 is still claimed in recent patents (6,7). Other researchers have reported that the reaction of DETA with fatty acids does not take place in a 1:1 molar ratio; hence fatty acid monoamides 3 and the related imidazoline derivatives 4 are unlikely (3,4,8). Additionally, discrepancies exist in the literature over the mechanism of the reaction, in particular the relative reactivities of the primary and secondary amines (3,4,8,9). To clarify the mechanism of this important thermal acylation reaction and to prepare fatty amides or imidazoline compounds that contain a free primary amine group, we have studied the reaction of fatty acids 1 and DETA 2, and report here the results of our studies. MATERIALS AND METHODS Materials and instrumentation.Melting points were measured with an Electrothermal IA9300 digital apparatus. Infrared (IR) spectra were recorded on a (CO 2 -free, dry airpurged) Digilab FTS-7 Fourier transform infrared (FTIR) spectrophotometer (Biorad, Cambridge, MA). 1 H nuclear magnetic resonance (NMR) (300 MHz) spectra (CDCl 3 ) were obtained with a Bruker AC-300 instrument (Bruker, Germany) (Me 4 Si as reference). Mass spectra were measured in a Varian VG70-250S double-focusing magnetic-sector instrument (VG Analytical, Manchester, England) at 15 ev. A model 8452A diode-array spectrophotometer (HewlettPackard, Palo Alto, CA) was used for quantitative analysis of the Schiff base-forming reactions. The analysis procedure was as follows: 20-60 mg of fatty amine compound was dissolved in 2 mL CHCl 3 in a 10-mL volumetric flask. Glacial acetic acid (0.35 mL) and salicylaldehyde (0.60 mL) were added, and the flask was placed in a water bath at 30°C. After 1 h, the solution was made up to 10.0 mL with CHCl 3 , and the absorption at 4...

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“…Primary amides are known to dehydrate to the corresponding nitrile upon pyrolysis. [30,44] 1,2-Diamines are known [40,41] to react with carboxylic acids to yield 2-alkyl-4,5-dihydroimidazoles. 2-Heptadecyl-4,5-dihydroimidazole (6) can be prepared from EBS by heating for 3 days at 240°C to 260°C, albeit in low yield.…”

Section: E Reaction Mechanismsmentioning

confidence: 99%

Lubricant pyrolysis during sintering of powder metallurgy compacts

Baum

Becker

Lappas

et al. 2004

Metall Mater Trans B

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The chemistry surrounding the pyrolysis of N,NЈ-ethylenebisstearimide (EBS) compacted with iron powder is described for the first time. Heat treatment is carried out in a 5 vol pct hydrogen atmosphere (balance nitrogen) over the 100°C to 850°C range. The exhaust from the furnace is monitored by Fourier transform infrared and dispersive ultraviolet absorption spectroscopy; condensable materials are analyzed by gas chromatography/mass spectrometry (GC/MS). A wide range of analytes emitted from the preceding process were characterized. The aliphatic CH stretch in the 3000 to 2700 cm Ϫ1 range and the asymmetric CO stretch in gaseous CO 2 at 2350 cm Ϫ1 are excellent indicators of the extent of delubrication. A bimodal CO emission phase is observed in the temperature window between delubrication and sintering. Three major large molecule reaction products, along with five minor compounds, are identified by GC/MS. A preliminary reaction mechanism is inferred based on product analysis and known organic chemistry. It appears that hydrolysis of EBS competes with ␥-H abstraction yielding an N-vinyl amide and stearamide, which undergoes further reaction. Hydrolysis affords stearic acid, which decarboxylates to heptadecane, and 2-heptadecyl-4,5-dihydroimidazole via ring closure of the corresponding amino-amide.

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The Chemistry of the 2-Imidazolines and Imidazolidines.

Cited by 94 publications

References 49 publications

Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐¹¹C] imidazole: the I₂ imidazoline receptor ligand [¹¹C] benazoline

Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐¹¹C] imidazole: the I₂ imidazoline receptor ligand [¹¹C] benazoline

Thermal reactions of fatty acids with diethylene triamine

Lubricant pyrolysis during sintering of powder metallurgy compacts

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The Chemistry of the 2-Imidazolines and Imidazolidines.

Cited by 94 publications

References 49 publications

Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐11C] imidazole: the I2 imidazoline receptor ligand [11C] benazoline

Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐11C] imidazole: the I2 imidazoline receptor ligand [11C] benazoline

Thermal reactions of fatty acids with diethylene triamine

Lubricant pyrolysis during sintering of powder metallurgy compacts

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Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐¹¹C] imidazole: the I₂ imidazoline receptor ligand [¹¹C] benazoline

Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐¹¹C] imidazole: the I₂ imidazoline receptor ligand [¹¹C] benazoline