Modification of Preparation of Diazomethane for Methyl Esterification of Environmental Samples Analysis by Gas Chromatography

Ngan, Fung; Toofan, Mahmood

doi:10.1093/chromsci/29.1.8

Cited by 41 publications

(34 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Secondly, the need for distillation and the use of a concentrated ethereal solution of diazomethane presented a considerable hazard owing to the toxic and potentially explosive nature of such a solution. We found that when the bubbler method, hitherto used only for the esterification of acids, [17] was modified to allow the synthesis of diazo ketones, yields as high as 75% (based on 4) could be obtained. In this method, diazomethane is bubbled through a freshly prepared solution of [1,2-13 C 2 ]benzyloxyacetyl chloride in diethyl ether.…”

Section: Discussionmentioning

confidence: 99%

Chemo-Enzymatic Synthesis of Thymidine13C-Labelled in the 2′-Deoxyribose Moiety

Ouwerkerk¹,

Boom²,

Lugtenburg³

et al. 2000

Eur. J. Org. Chem.

View full text Add to dashboard Cite

A synthesis of [3′,4′‐13C2]thymidine (1) is described in which [13C2]acetic acid (2) is converted into the nucleoside in twelve steps with 9% overall yield. D‐2‐Deoxyribose‐5‐phosphate aldolase (DERA, EC 4.1.2.4) and triosephosphate isomerase (TPI, EC 5.3.1.1) are used for the stereocontrolled formation of D‐[3,4‐13C2]‐2‐deoxyribose‐5‐phosphate (8) from [2,3‐13C2]dihydroxyacetone monophosphate (DHAP, 7) and acetaldehyde in 80% yield. The route permits the introduction of isotopically enriched carbon atoms at any position or combination of positions in the furanose ring and the product can be coupled with any of the four naturally occurring base moieties.

show abstract

Section: Discussionmentioning

confidence: 99%

Chemo-Enzymatic Synthesis of Thymidine13C-Labelled in the 2′-Deoxyribose Moiety

Ouwerkerk¹,

Boom²,

Lugtenburg³

et al. 2000

Eur. J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…Mass measurements were the averages of at least 10 consecutive scans. Analysis of Methylated N-Arachidonylglycine-For the production of methyl esters, a solution of diazomethane in ether was prepared from Diazald (Aldrich) using the apparatus and conditions described in the literature (8). This was added in excess to an ether solution of the sample to be methylated and kept at room temperature for 1 h. One drop of glacial acetic acid was then added to consume excess diazomethane.…”

Section: Methodsmentioning

confidence: 99%

Identification of a New Class of Molecules, the Arachidonyl Amino Acids, and Characterization of One Member That Inhibits Pain

Huang

Bisogno

Petros

et al. 2001

Journal of Biological Chemistry

315

347

View full text Add to dashboard Cite

In mammals, specific lipids and amino acids serve as crucial signaling molecules. In bacteria, conjugates of lipids and amino acids (referred to as lipoamino acids) have been identified and found to possess biological activity. Here, we report that mammals also produce lipoamino acids, specifically the arachidonyl amino acids. We show that the conjugate of arachidonic acid and glycine (N-arachidonylglycine (NAGly)) is present in bovine and rat brain as well as other tissues and that it suppresses tonic inflammatory pain. The biosynthesis of NAGly and its degradation by the enzyme fatty acid amide hydrolase can be observed in rat brain tissue. In addition to NAGly, bovine brain produces at least two other arachidonyl amino acids: N-arachidonyl ␥-aminobutyric acid (NAGABA) and N-arachidonylalanine. Like NAGly, NAGABA inhibits pain. These findings open the door to the identification of other members of this new class of biomolecules, which may be integral to pain regulation and a variety of functions in mammals.Molecules found in bacteria that consist of a lipid moiety conjugated to an amino acid have been termed lipoamino acids (1-3). Burstein et al. (4) found that the lipoamino acid Narachidonylglycine (NAGly) 1 causes hot plate analgesia in mice, indicating its possible biological relevance in mammals. NAGly was first synthesized (5) as a structural analog of the endogenous cannabinoid anandamide (6), and it was found to lack affinity for the cannabinoid CB1 receptor. We hypothesized that NAGly may be produced by mammalian tissues because it is composed of the naturally occurring compounds glycine and arachidonic acid. Herein we show that at least three arachidonyl amino acids are natural constituents in mammalian brain: NAGly, N-arachidonyl ␥-aminobutyric acid (NAGABA), and N-arachidonylalanine (NAAla). One member of this group, NAGly, is characterized in detail here. It is synthesized in situ in rat brain tissue from the precursors arachidonic acid and glycine, and it is hydrolyzed by the enzyme fatty acid amide hydrolase (FAAH). NAGly is widely distributed among mammalian tissues, implying multiple functions. One possible physiological function of NAGly is pain suppression, indicated by its marked suppression of formalininduced pain behavior in rats, confirming a previous report of analgesic activity in mice (4). EXPERIMENTAL PROCEDURESTissue Extraction and Purification-The procedure comprised a liquidliquid extraction modified from that described by Folch et al. (7) followed by a series of solid-phase separations. Fresh bovine brain and rat organs were homogenized in the methanol fraction of 20 volumes of 2:1 chloroform:methanol and centrifuged for 15 min at 31,000 ϫ g at 4°C. Chloroform was then added to the supernatant. NaCl (0.2 volume, 0.73%) was mixed with the crude homogenate, and the solution was allowed to separate overnight at 4°C or centrifuged at 1,000 ϫ g for 15 min. The upper phase was discarded and the interphase washed twice. The lower phase was then applied to diethylaminopropyl silica-based...

show abstract

“…Acids 1 and 2 were converted respectively to methyl 2-(4-chloro-2-methylphenoxy) propanoate, 3, and methyl 2-(2,4-dichlorophenoxy) propanoate, 4, by reacting acids with diazomethane. 19 Diazald and diazomethane generation apparatus were purchased from Aldrich (Milwaukee, WI).…”

Section: Methodsmentioning

confidence: 99%

Absolute configurations of chiral herbicides determined from vibrational circular dichroism

Wang

Polavarapu

2005

Chirality

View full text Add to dashboard Cite

Enantiopure herbicides (+)-2-(4-chloro-2-methylphenoxy) propanoic acid, (+)-1 and (+)-2-(2,4-dichlorophenoxy) propanoic acid, (+)-2 were investigated using vibrational circular dichroism (VCD). Experimental absorption and VCD spectra of (+)-1 and (+)-2 in CDCl3 solution in the 2000-900 cm(-1) region were compared with the ab initio predictions of absorption and VCD spectra obtained with density functional theory using the B3LYP/6-31G* basis set for different conformers of (R)-1 and (R)-2. Due to the intermolecular hydrogen bonding, this comparison did not provide unambiguous conclusions. To eliminate intermolecular hydrogen bonding influence, the two acids 1 and 2 were converted to the corresponding methyl esters, namely, (+)-methyl 2-(4-chloro-2-methylphenoxy) propanoate, (+)-3 and (+)-methyl 2-(2,4-dichlorophenoxy) propanoate, (+)-4. The experimental VCD spectra were measured for these esters and ab initio calculations for different conformers of (R)-3 and (R)-4 were carried out. The experimental VCD spectra and corresponding population-weighted theoretical VCD spectra were found to be in excellent agreement, which allowed unambiguous determination of absolute configuration of 3 and 4 as (+)-(R). Since esterification does not invert the configuration, the absolute configuration of the parent acids 1 and 2 is the same as that of corresponding methyl esters.

show abstract

Modification of Preparation of Diazomethane for Methyl Esterification of Environmental Samples Analysis by Gas Chromatography

Cited by 41 publications

References 0 publications

Chemo-Enzymatic Synthesis of Thymidine13C-Labelled in the 2′-Deoxyribose Moiety

Chemo-Enzymatic Synthesis of Thymidine13C-Labelled in the 2′-Deoxyribose Moiety

Identification of a New Class of Molecules, the Arachidonyl Amino Acids, and Characterization of One Member That Inhibits Pain

Absolute configurations of chiral herbicides determined from vibrational circular dichroism

Contact Info

Product

Resources

About