scholarly journals Sorption of Hydrogen Chloride and Trifluoroacetic Acid on Poly-l-valine and Poly-l-leucine

1964 ◽  
Vol 239 (5) ◽  
pp. 1442-1446
Author(s):  
W.W. Brandt ◽  
R.S. Budrys
2015 ◽  
Vol 11 ◽  
pp. 37-41 ◽  
Author(s):  
Mingfeng Yu ◽  
Joseph K-H Wong ◽  
Cyril Tang ◽  
Peter Turner ◽  
Matthew H Todd ◽  
...  

The effective and efficient removal of the BF2 moiety from F-BODIPY derivatives has been achieved using two common Brønsted acids; treatment with trifluoroacetic acid (TFA) or methanolic hydrogen chloride (HCl) followed by work-up with Ambersep® 900 resin (hydroxide form) effects this conversion in near-quantitative yields. Compared to existing methods, these conditions are relatively mild and operationally simple, requiring only reaction at room temperature for six hours (TFA) or overnight (HCl).


1983 ◽  
Vol 36 (4) ◽  
pp. 833 ◽  
Author(s):  
A Kirkpatrick ◽  
JA Maclaren

1,1-Disubstituted 1,2,3,4-tetrahydro-β-carbolines are formed by the action of trifluoroacetic acid on enamines derived from tryptamine or tryptophan. With methanolic hydrogen chloride, either cyclization to the corresponding β-carboline derivative, or acidolysis to regenerate the parent amine, occurs. The course of this reaction depends on the substitution pattern. Mixtures of products are not formed. Authentic phenacyl L-tryptophanate hydrochloride has been synthesized.


1985 ◽  
Vol 38 (5) ◽  
pp. 745 ◽  
Author(s):  
RC Cambie ◽  
GR Clark ◽  
TC Jones ◽  
PS Rutledge ◽  
GA Strange ◽  
...  

Penam (4-thia-1-azabicyclo[3.2.0]heptan-7-one) and 2,3-disubstituted penams are prepared conveniently from vic-iodo isothiocyanates beginning with the facile cyclization of the latter with di -t-butyl sodiomalonates. Treatment of the resulting di -t-butyl 2-(thiazolidin-2- ylene ) malonates with trifluoroacetic acid gives t-butyl 2-thiazolin-2- ylacetate derivatives which are reduced to the corresponding thiazolidines with aluminium amalgam. Cleavage of these t-butyl esters with hydrogen chloride affords β-amino acid hydrochlorides, which are cyclized to penam and its derivatives with 1-[3-( dimethylamino ) propyl ]- 3-ethylcarbodiimide hydrochloride. The structures of the (2α,3aβ,7aβ)- thiazolidine (5) and of the tricyclic β- lactam (41) have been confirmed by X-ray crystallography.


2019 ◽  
Author(s):  
Elena Prigorchenko ◽  
Sandra Kaabel ◽  
Triin Narva ◽  
Anastassia Baškir ◽  
Maria Fomitšenko ◽  
...  

Amplification of a thermodynamically unfavoured macrocyclic product through the directed shift of the equilibrium between dynamic covalent chemistry library members is difficult to achieve. We show for the first time that during condensation of formaldehyde and <i>cis</i>-<i>N,N'</i>-cyclohexa-1,2-diylurea formation of <i>inverted-cis</i>-cyclohexanohemicucurbit[6]uril (<i>i-cis</i>-cycHC[6]) can be induced at the expense of thermodynamically favoured <i>cis</i>-cyclohexanohemicucurbit[6]uril (<i>cis</i>-cycHC[6]). The formation of <i>i-cis-</i>cycHC[6] is enhanced in low concentration of the templating chloride anion and suppressed in excess of this template. We found that reaction selectivity is governed by the solution-based template-aided dynamic combinatorial chemistry and continuous removal of the formed cycHC[6] macrocycles from the equilibrating solution by precipitation. Notably, the <i>i-cis</i>-cycHC[6] was isolated with 33% yield. Different binding affinities of three diastereomeric <i>i-cis</i>-, <i>cis</i>-cycHC[6] and their chiral isomer (<i>R,R</i>)-cycHC[6] for trifluoroacetic acid demonstrate the influence of macrocycle geometry on complex formation.


2018 ◽  
Vol 15 (10) ◽  
pp. 891-894 ◽  
Author(s):  
Zhu-Qing Wang ◽  
Meng-Ping Guo ◽  
Yong-Ju Wen ◽  
Xiu-Li Shen ◽  
Mei-Yun Lv ◽  
...  

1985 ◽  
Vol 50 (8) ◽  
pp. 1842-1851 ◽  
Author(s):  
Petr Švec

The course of chlorination of 2,4,6-trichlorophenol (I) in water and approximately 20% sulfuric and hydrochloric acids has been investigated. In all these media the reaction gives primarily 2,4,6,6-tetrachloro-2,4-cyclohexadienone (II) which is subsequently chlorinated under formation of polychlorinated alicyclic ketones or isomerized to give the more stable 2,4,6,6-tetrachloro-2,5-cyclohexadienone (III), the precursor of further arising chlorinated 1,4-benzoquinones. The ratio of the arising polychlorinated alicyclic ketones to chlorinated 1,4-benzoquinones is significantly influenced by concentration of hydrogen chloride in the reaction medium. On the basis of model experiments, the reaction mechanism of exhaustive chlorination of 2,4,6-trichlorophenol has been suggested.


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