Biscitraconimides as Anti-Reversion Agents for Diene Rubbers: Spectroscopic Studies on Citraconimide-Squalene Adducts

1997 ◽  
Vol 70 (1) ◽  
pp. 129-145 ◽  
Author(s):  
R. N. Datta ◽  
A. H. M. Schotman ◽  
A. J. M. Weber ◽  
F. G. H. van Wijk ◽  
P. J. C. van Haeren ◽  
...  
Keyword(s):  
Minor Component ◽  
Spectroscopic Studies ◽  
Model System ◽  
Diels Alder ◽  
Main Reaction ◽  
Reaction Products ◽  
Ene Reaction ◽  
Simple Model System ◽  
Conjugated Polyenes ◽  
Diene Rubbers

Abstract The mechanism of anti-reversion activity of biscitraconimides (BCI) during rubber vulcanization has been investigated. Biscitraconimides form crosslinks by reaction with chain modifications which are formed during the reversion process. These additional crosslinks compensate for the sulfidic crosslinks that are lost during the reversion. To allow structural assignments of the adducts formed between rubber and citraconimides, squalene has been used as a simple model system in combination with the currently used additives and sulphur. The products were identified as Diels—Alder adducts of conjugated polyenes, formed during reversion, with citraconimide. The nuclear magnetic resonance (NMR) spectroscopic assignments of the products are discussed. Furthermore the quantification of squalene-BCI adducts via NMR and mass spectrometry (MS) using 13C labelled 1,3-bis (citraconimidomethyl) benzene (BCI-MX) is described. It was found that under the applied conditions (2 h, 170 °C), approximately 80% of the citraconimide groups are converted into squalene-BCI adducts. Diels—Alder adducts are the main reaction products of the reaction. Products from an ene reaction are formed as minor component (less than 20%).

Nitrosocarbonyl Carbohydrate Derivatives: Hetero Diels–Alder and Ene Reaction Products for Useful Organic Synthesis

Synthesis ◽  
2020 ◽  
Author(s):  
Paolo Quadrelli ◽  
Marco Corti ◽  
Marco Leusciatti ◽  
Mattia Moiola ◽  
Mariella Mella
Keyword(s):  
Organic Synthesis ◽  
Tertiary Amine ◽  
Diels Alder ◽  
Mild Oxidation ◽  
Reaction Products ◽  
Ene Reaction ◽  
Nitrile Oxides

AbstractThe generation and trapping of two new nitrosocarbonyl intermediates bearing carbohydrate-based chiral substituents is achieved by the mild oxidation of the corresponding nitrile oxides with tertiary amine N-oxides. Their capture with suitable dienes and alkenes afforded the corresponding hetero Diels–Alder cycloadducts and ene adducts from fair to excellent yields. The entire methodology looks highly promising by the easy conversion of aldoximes into hydroxymoyl halides, widening the access to nitrosocarbonyls, versatile tools in organic synthesis.

Studies on a New Antireversion Agent for Sulfur Vulcanization of Diene Rubbers

1996 ◽  
Vol 69 (5) ◽  
pp. 727-741 ◽  
Author(s):  
A. H. M. Schotman ◽  
P. J. C. van Haeren ◽  
A. J. M. Weber ◽  
F. G. H. van Wijk ◽  
J. W. Hofstraat ◽  
...  
Keyword(s):  
Crosslink Density ◽  
Alder Reaction ◽  
Diels Alder ◽  
Spectroscopic Methods ◽  
Diels Alder Reaction ◽  
Sulfur Vulcanization ◽  
Cure Time ◽  
Conjugated Polyenes ◽  
Diene Rubbers ◽  
Diene Rubber

Abstract The mechanism of biscitraconimides (BCI) as antireversion agents for sulfur vulcanized diene rubber was investigated choosing squalene as a model substrate. Curing of squalene with sulfur in the presence of accelerator, activator and BCI at 170°C gave BCI bridged adducts. The products were identified by spectroscopic methods as being results of a Diels-Alder reaction of BCI (dienophile) with conjugated polyenes that are formed as a result of reversion. The rate at which the sulfur network degrades is comparable to the rate in which BCI adduct is formed. As a result of this, a nearly constant crosslink density is obtained after optimum cure time (t90). Based on this concept, the advantage of using 1,3-bis-(citraconimidomethyl) benzene (BCI-MX), a representative of the BCI-class, in NR based compounds is examined.

Structural Study of an Unusual Diels-Alder Adduct

1992 ◽  
Vol 45 (12) ◽  
pp. 2089 ◽  
Author(s):  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Structural Study ◽  
Spectroscopic Studies ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Chemical Evidence ◽  
Alder Adduct

The structure of the compound obtained on heating the naturally occurring clerodane furanoditerpene (1) had been formulated as (2) on the basis of spectroscopic studies. A single-crystal X-ray diffraction study on the dihydro derivative of (2) has confirmed this and provides support for the stereochemistry previously assigned to (1) on the basis of chemical evidence.

Antimicrobial Activity of Gaseous Allyl Isothiocyanate

1997 ◽  
Vol 60 (8) ◽  
pp. 943-947 ◽  
Author(s):  
PASCAL J. DELAQUIS ◽  
PETER L. SHOLBERG
Keyword(s):  
Bacterial Species ◽  
Allyl Isothiocyanate ◽  
Model System ◽  
Penicillium Expansum ◽  
Escherichia Coli O157 ◽  
Fluorescent Pseudomonad ◽  
Bacterial Cells ◽  
E Coli ◽  
Simple Model System ◽  
Germination And Growth

A simple model system was constructed to evaluate the microbistatic and microbicidal properties of gaseous allyl isothiocyanate (AIT) against bacterial cells and fungal conidia deposited on agar surfaces. Salmonella typhimurium, Listeria monocytogenes Scott A, and Escherichia coli O157:H7 were inhibited when exposed to 1,000 μg AIT per liter. Pseudomonas corrugata, a Cytophaga species, and a fluorescent pseudomonad failed to grow in the presence of 500 μg AIT per liter. Germination and growth of Penicillium expansum, Aspergillus flavus, and Botrytis cinerea conidia was inhibited in the presence of 100 μg AIT per liter. Bactericidal and sporicidal activities varied with strain and increased with time of exposure, AIT concentration, and temperature. E. coli O157:H7 was the most resistant bacterial species tested.

ChemInform Abstract: Formal [2 + 2 + 2] Cycloaddition Strategy Based on an Intramolecular Propargylic Ene Reaction/Diels-Alder Cycloaddition Cascade.

ChemInform ◽  
2010 ◽  
Vol 42 (1) ◽  
pp. no-no
Author(s):  
Julia M. Robinson ◽  
Takeo Sakai ◽  
Katsuhiko Okano ◽  
Takafumi Kitawaki ◽  
Rick L. Danheiser
Keyword(s):  
Diels Alder ◽  
Ene Reaction

Cyclization of the Ene Reaction Products from Hexafluoracetone Imine: Synthesis of Bis(trifluoromethyl)pyrrolidine Derivatives

Heterocycles ◽  
1995 ◽  
Vol 40 (2) ◽  
pp. 753 ◽  
Author(s):  
Itsumaro Kumadaki ◽  
Tetsuo Shimada ◽  
Akihiro Fujimoto ◽  
Toshiyuki Takagi ◽  
Mayumi Koyama ◽  
...  
Keyword(s):  
Reaction Products ◽  
Ene Reaction

Synthesis of Trifluoromethylated Tetrahydropyrans from Ene Reaction Products of Trifluoromethyl Ketones: Synthesis of Fluorine Analogs of a Sesquiterpene

Heterocycles ◽  
1992 ◽  
Vol 33 (1) ◽  
pp. 51 ◽  
Author(s):  
Itsumaro Kumadaki ◽  
Takabumi Nagai ◽  
Hiroshi Ohtsuka ◽  
Mayumi Koyama ◽  
Akira Ando ◽  
...  
Keyword(s):  
Reaction Products ◽  
Ene Reaction ◽  
Trifluoromethyl Ketones

scholarly journals Zur Reaktivität des Germaethens Me2Ge=C(SiMe3)2: Mechanistische Aspekte der Diels-Aider- und En-Reaktionen [1] / On the Reactivity of Germaethene Me2Ge=C (SiMe3)2: Mechanistic Aspects of Diels Alder and Ene Reactions [1]

1996 ◽  
Vol 51 (6) ◽  
pp. 838-850 ◽  
Author(s):  
Nils Wiberg ◽  
Susanne Wagner
Keyword(s):  
Double Bond ◽  
Energy Difference ◽  
Diels Alder ◽  
Bond Polarity ◽  
Ene Reactions ◽  
Ene Reaction

Abstract Diels-Alder and ene reactions of germaethene Me2Ge=C(SiMe3)2 (2) with butadienes respectively, take place regioselectively, as well as stereoselectively. They are accelerated by an increasing tendency of substituents in butadiene or propene to donate electrons (e.g. 2-methylbutadiene > butadiene; 2-methylpropene > propene), and retarded by an increasing bulkyness of substituents in 1,4- or 1,3-positions (e.g. 1-methylbutadiene > 2-methylbutadiene; 1-vinylpropene > propene). It is concluded from these studies that Diels-Alder and ene reactions of 2 occur - like those of Me2Si=C(SiMe3)2 (1) or of ethenes >C=C< - in a concerted way and are HOMOdiene-LUMOdienophile and HOMOene-LUMOenophile controlled. Thus 2 and 1 behave as carbon analogues. With regard to a specific diene or ene (e.g. anthracene; toluene), 2 is the better dienophile or enophile than 1 or ethenes. With a fixed diene/ene mixture (e.g. butadiene/propene), 2 acts as the better dienophile, while 1 is the better enophile. These results can be explained by the π/π*- energy difference and the double bond polarity decreasing in the direction 1 > 2. Only cis-piperylene gives a [2+2] cycloadduct with 2. besides two [4+2] cycloadducts, and an ene reaction product

scholarly journals Use of Coal Bottom Ash and CaO-CaCl2-Activated GGBFS Binder in the Manufacturing of Artificial Fine Aggregates through Cold-Bonded Pelletization

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5598
Author(s):  
Dongho Jeon ◽  
Woo Sung Yum ◽  
Haemin Song ◽  
Seyoon Yoon ◽  
Younghoon Bae ◽  
...  
Keyword(s):  
Early Stage ◽  
Bottom Ash ◽  
Relative Weight ◽  
Main Reaction ◽  
Reaction Products ◽  
Coal Bottom Ash ◽  
Heavy Metal Leaching ◽  
Granulated Blast Furnace Slag ◽  
Fine Aggregates ◽  
Cementless Binder

This study investigated the use of coal bottom ash (bottom ash) and CaO-CaCl2-activated ground granulated blast furnace slag (GGBFS) binder in the manufacturing of artificial fine aggregates using cold-bonded pelletization. Mixture samples were prepared with varying added contents of bottom ash of varying added contents of bottom ash relative to the weight of the cementless binder (= GGBFS + quicklime (CaO) + calcium chloride (CaCl2)). In the system, the added bottom ash was not simply an inert filler but was dissolved at an early stage. As the ionic concentrations of Ca and Si increased due to dissolved bottom ash, calcium silicate hydrate (C-S-H) formed both earlier and at higher levels, which increased the strength of the earlier stages. However, the added bottom ash did not affect the total quantities of main reaction products, C-S-H and hydrocalumite, in later phases (e.g., 28 days), but simply accelerated the binder reaction until it had occurred for 14 days. After considering both the mechanical strength and the pelletizing formability of all the mixtures, the proportion with 40 relative weight of bottom ash was selected for the manufacturing of pilot samples of aggregates. The produced fine aggregates had a water absorption rate of 9.83% and demonstrated a much smaller amount of heavy metal leaching than the raw bottom ash.

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