t-Butyl bromide–dimethyl sulphoxide reactions. Pummerer-like reaction with carboxylic acids and N-protected amino-acids

1981 ◽  
pp. 2737-2739 ◽  
Author(s):  
Arnaldo Dossena ◽  
Rosangela Marchelli ◽  
Giuseppe Casnati
Keyword(s):  
Amino Acids ◽  
Carboxylic Acids ◽  
Dimethyl Sulphoxide ◽  
Butyl Bromide

Microwave-Assisted Esterification of Diverse Carboxylic Acids and Chiral Amino Acids

2008 ◽  
Vol 38 (23) ◽  
pp. 4107-4115 ◽  
Author(s):  
Qian Yang ◽  
Xiao-jian Wang ◽  
Zhi-yu Li ◽  
Li Sun ◽  
Qi-dong You
Keyword(s):  
Amino Acids ◽  
Carboxylic Acids ◽  
Microwave Assisted ◽  
Chiral Amino Acids

Prebiotic synthesis of carboxylic acids, amino acids and nucleic acid bases from formamide under photochemical conditions⋆

2017 ◽  
Vol 132 (7) ◽  
Author(s):  
Lorenzo Botta ◽  
Bruno Mattia Bizzarri ◽  
Davide Piccinino ◽  
Teresa Fornaro ◽  
John Robert Brucato ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nucleic Acid ◽  
Carboxylic Acids ◽  
Prebiotic Synthesis ◽  
Nucleic Acid Bases

Facile synthesis of tert-butyl ester of N-protected amino acids with tert-butyl bromide

1993 ◽  
Vol 34 (46) ◽  
pp. 7409-7412 ◽  
Author(s):  
Pierre Chevallet ◽  
Patrick Garrouste ◽  
Barbara Malawska ◽  
Jean Martinez
Keyword(s):  
Amino Acids ◽  
Butyl Ester ◽  
Facile Synthesis ◽  
Butyl Bromide ◽  
Tert Butyl

ε-Amino acids based on bicyclic skeleton: bicyclo[3.3.0]octane-5-amino-1-carboxylic acids

2006 ◽  
Vol 47 (41) ◽  
pp. 7389-7393 ◽  
Author(s):  
Sung Jin Yeo ◽  
Kyung Seok Jeong ◽  
Hogyu Han ◽  
Jaheon Kim ◽  
Nakcheol Jeong
Keyword(s):  
Amino Acids ◽  
Carboxylic Acids

scholarly journals The Impact of (bio-)organic substances on the ice nucleation activity of the K-feldspar microcline in aqueous solutions

2021 ◽  
Author(s):  
Kristian Klumpp ◽  
Claudia Marcolli ◽  
Thomas Peter
Keyword(s):  
Amino Acids ◽  
Citric Acid ◽  
Carboxylic Acids ◽  
Water Activity ◽  
Active Sites ◽  
Ice Nucleation ◽  
Organic Substances ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Impact

Abstract. Potassium-feldspars (K-feldspars), such as microcline, are considered key dust minerals inciting ice nucleation in mixed phase clouds. Besides the high ice nucleation activity of microcline, recent studies also revealed a high sensi-tivity of microcline towards interaction with solutes on its surface. Here, we investigate the effect of organic and bio-organic substances on the ice nucleation activity of microcline, with the aim to better understand the underlying sur-face interactions. We performed immersion freezing experiments with microcline in solutions of three carboxylic acids, five amino acids and two polyols to represent these compound classes. By means of a differential scanning calorimeter we investigated the freezing of emulsified droplets of microcline suspended in various solutions. Depend-ing on the type of solute, different effects were observed. In the case of carboxylic acids (acetic, oxalic and citric acid), the measured heterogeneous onset temperatures, Thet, showed no significant deviation from the behavior pre-dicted by the water activity criterion, Thet(aw) = Tmelt(aw+Δaw), which relates Thet with the melting point temperature Tmelt via a constant water activity offset Δaw. While this behavior could be interpreted as a lack of interaction of the solute molecules with the surface, the carboxylic acids caused the fraction of heterogeneously frozen water, Fhet(aw), to decrease by up to 40 % with increasing solute concentrations. In combination, unaltered Thet(aw) and reduced Fhet(aw) suggest that active sites were largely deactivated by the acid molecules, but amongst those remaining active are also the best sites with the highest Thet. A deviation from this behavior is citric acid, which showed not only a de-crease in Fhet, but also a decrease in Thet of up to 4 K for water activities below 0.99, pointing to a depletion of the best active sites by interactions with the citrate ions. When neutralized solutions of the acids were used instead, the de-crease in Fhet became even more pronounced. The slope of Thet(aw) was different for each of the neutralized acid solu-tions. In the case of amino acid solutions, we found a decrease in Thet (up to 10 K), significantly below the Δaw-criterion, as well as a reduction in Fhet (up to 60 %). Finally, in case of the investigated polyols, no significant devia-tion of Thet from the Δaw-criterion was observed, and no significant deviation of Fhet in comparison to a pure water suspension was found. Furthermore, we measured the effects of aging on the ice nucleation activity in experiments with microcline suspended in solutions for up to seven days, and tested the reversibility of the interaction with the solutes after aging for 10 days. For citric acid, an ongoing irreversible degradation of the ice nucleation activity was observed, whereas the amino acids showed completely reversible effects. In summary, our experiments demonstrate a remarkable sensitivity of microcline ice nucleation activity to surface interactions with various solutes, underscoring the importance of the history of such particles from source to frozen cloud droplet in the atmosphere.

Unnatural amino acids. 3. Aziridinyl ketones from esters and amides of aziridine-2-carboxylic acids

2007 ◽  
Vol 43 (2) ◽  
pp. 169-174 ◽  
Author(s):  
B. Shtrumfs ◽  
J. Hermane ◽  
I. Kalvinsh ◽  
P. Trapencieris
Keyword(s):  
Amino Acids ◽  
Carboxylic Acids ◽  
Unnatural Amino Acids
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