Experimental and modeling studies on the synthesis and properties of higher fatty esters of corn starch

This paper describes a systematic study on the synthesis of higher fatty esters of corn starch (starch laurate and starch stéarate) by using the corresponding vinyl esters. The reactions were carried out in DMSO using basic catalysts (Na2HPO4, K2CO3, and Naacetate). The effect of the process variables (vinyl ester to starch ratio, catalyst intake, reaction temperature and type of the catalyst) on the degree of substitution (DS) of the starch laurate and starch stearate esters was determined by performing a total of 54 experiments. The results were adequately modeled using a non-linear multivariable regression model (R2≥0. 96). The basicity of the catalyst and the reaction temperature have the highest impact on the product DS. The thermal and mechanical properties of some representative product samples were determined. High-DS products (DS = 2.26-2.39) are totally amorphous whereas the low-DS ones (DS = 1.45-1.75) are still partially crystalline. The thermal stability of the esterlfied products is higher than that of native starch. Mechanical tests show that the products have a tensile strength (stress at break) between 2.7-3.5 MPa, elongation at break of 3-26%, and modulus of elasticity of 46-113 MPa.

From crops to products for crops: preserving the ecosystem through the use of bio-based molecules

In a context of dwindling oil reserves and environmental pressures, the chemical industry needs to innovate by developing new processes for producing bioproducts from raw plant materials. Unsaturated fatty acids from vegetable oils constitute a highly promising renewable resource that can be used to diversify productions, decreasing reliance on petroleum. A starting material rich in oleic acid has been obtained through the selection of high-oleic sunflower varieties and enzymatic hydrolysis of the oil they produce. The double bonds of this unsaturated raw material have been cleaved in green oxidizing conditions involving a biphasic lipophilic-aqueous system including hydrogen peroxide as an oxidant and a peroxo-tungsten complex Q3 {PO2[WO(O2)2]4} as a phase-transfer catalyst (PTC) and co-oxidant. This PTC efficiently transferred oxygen to the substrate in the lipophilic phase. A mono-acid (pelargonic acid) and a di-acid (azelaic acid), with shorter, unusual hydrocarbon chains not present in the natural state, were synthesized and purified through an intensive process. Pelargonic acid was then formulated as an environmentally friendly biocontrol agent for weeds. We extended this green process of oxidative scission to other fatty acids and derivatives, to obtain other short-chain acids with diverse potential applications. This production chain (crops, reaction and purification processes, products, applications) is based on a sustainable development strategy. Dans un contexte de diminution des réserves fossiles et de pressions réglementaires et environnementales, l’industrie chimique tend à innover en développant de nouveaux procédés pour la production de bioproduits d’origine végétale. Les acides gras insaturés d’une huile végétale constitue une ressource renouvelable prometteuse qui peut être utilisée pour diversifier les productions et réduire la dépendance vis-à-vis du pétrole. Dans cet article, une matière première riche en acide oléique a été obtenue par l’hydrolyse enzymatique de l’huile de tournesol hautement oléique, obtenue par sélection variétale. Les doubles liaisons de cette matière première insaturée ont été clivées dans des conditions oxydantes impliquant un système biphasique aqueux-lipophile, avec le peroxyde d’hydrogène comme oxydant et le complexe peroxo-tungtène Q3{PO2[WO(O2)2]4} comme catalyseur de transfert de phase (CTP) et co-oxydant. Ce CTP a permis d’assurer un transfert efficace vers le substrat en phase lipophile. Un mono-acide (acide pélargonique) et un di-acide (acide azélaïque) à chaînes impaires plus courtes, peu présentes à l’état naturel, ont été ainsi synthétisés et purifiés grâce à un procédé intensifié. L’acide pélargonique a été formulé en tant qu’agent de biocontrôle écocompatible. Ce procédé vert de scission oxydante a été appliqué à d’autres acides gras et à leurs dérivés pour obtenir de nouveaux acides à chaînes courtes ayant différentes applications potentielles. Cette filière de production (culture, procédés de transformation et de purification, produits et leurs application) est basée sur une stratégie de développement durable

Nouveaux procédés verts d'oxydation de l'acide oléique

Dans un contexte de raréfaction des ressources pétrolières et de pressions environnementales, l industrie chimique a besoin d'innover en développant de nouvelles filières destinées à l'élaboration de bioproduits, à partir de matières premières d'origine végétale. Les acides gras insaturés obtenus à partir des huiles végétales, constituent ainsi une ressource renouvelable à fort potentiel permettant de diversifier les approvisionnements d'origine pétrolière. Notre intérêt s'est porté sur la réaction de scission oxydative d acides gras insaturés pour conduire à des monoacides et diacides à chaînes courtes et impaires, peu ou pas disponibles à l état naturel. Ce type de chaînes hydrocarbonées est recherché dans l industrie, car elles possèdent des propriétés spécifiques, mais elles ne sont actuellement produites qu'à partir de ressources fossiles. L'objectif était donc de mettre au point un procédé de clivage oxydatif performant, moins onéreux et moins polluant que l ozonolyse, le seul procédé industriel opérationnel. Les conditions oxydantes sélectionnées font appel à l eau oxygénée en tant qu oxydant, associée à un catalyseur de transfert de phase, sans avoir recours à un solvant organique. Plusieurs catalyseurs de transfert de phase Q3{PO4[WO(O2)2]4} ont été préparés à partir de l acide tungstophosphorique, d eau oxygénée et d'un sel d ammonium quaternaire (Q+,Cl-), afin de comparer leur efficacité à transférer l'oxygène vers le substrat en phase organique. Une optimisation des paramètres réactionnels a été effectuée avec le catalyseur le plus performant. De plus, deux protocoles ont été mis au point, pour la préparation in-situ du catalyseur et pour sa récupération en fin de réaction. Le procédé a été généralisé à des dérivés d acides gras dans le but d obtenir d'autres acides à chaînes courtes, répondant à une large gamme d'applications. Le gain environnemental lié à ce nouveau procédé a été évalué par le calcul d indicateurs verts. Afin d envisager un recyclage plus aisé du catalyseur, l anion oxodiperoxotungstate {PO4[WO(O2)2]4}3-, l espèce active du catalyseur, a été supporté sur des résines échangeuses d anions. Deux types de résines macroporeuses ont été testées : des résines commerciales (Amberlite IRA 900 et Lewatit K7367) et des résines modifiées (type Merrifield). Nous avons montré que ces dernières conduisent à de meilleurs rendements de scission oxydative de l acide oléique que les résines commerciales, et ce, malgré la présence de solvants. Cependant, l immobilisation de l anion oxodiperoxotungstate sur les résines commerciales a permis la synthèse en une seule étape d acétals, composés présentant un grand intérêt pour la synthèse de dérivés à haute valeur ajoutée. En utilisant l acétone, à la fois comme réactif et solvant, nous avons obtenu de bons rendements en cétal. De plus, la réaction d acétalisation one-pot de l acide oléique a pu être étendue à d autres solvants (alcools), offrant la possibilité de synthétiser un large panel d acétals. Le procédé développé est particulièrement intéressant car il conduit directement à la synthèse d acétals ou de cétals à partir d un acide gras insaturé biosourcé, en évitant les étapes de réactions intermédiaires.In a context of scarce oil resources and environmental pressures, the chemical industry needs to innovate by developing new production chains aiming the design of bioproducts from biobased raw materials. Unsaturated fatty acids derived from vegetable oils, thus represents renewable resources with a great potential, allowing to diversify petroleum based supplies. Our interest is focused on the oxidative cleavage reaction of unsaturated fatty acids to yield mono-acids and di-acids with shorter and odd hydrocarbon chains, which are not available at a natural state. Such hydrocarbon chains are attractive for industry because they meet specific properties. But, they are currently only produced from fossil resources. Therefore, the objective was to develop an efficient method for oxidative cleavage, less expensive and less polluting than ozonolysis, the only operational industrial process. The selected oxidizing conditions employs hydrogen peroxide as oxidant, together with a phase transfer catalyst, without using an organic solvent. Several phase transfer catalysts Q3{PO4[WO(O2)2]4} were prepared from tungstophosphoric acid, hydrogen peroxide and a quaternary ammonium salt (Q+,Cl-), in order to compare their effectiveness in transferring oxygen to the substrate in the organic phase. An optimization of reaction parameters was carried out with the most performing catalyst. In addition, two protocols have been developed for the in-situ preparation of the catalyst and its recovery after reaction. The method was extended to fatty acids derivatives, in order to obtain other short chain acids, having a wide range of applications. The environmental benefits associated with this new method were evaluated by calculating green indicators. To consider an easier recycling of the catalyst, the oxodiperoxotungstate anion {PO4[WO(O2)2]4}3-, the active species of the catalyst was supported on anion-exchange resins. Two types of macroporous resins were tested: commercial resins (Amberlite IRA 900 and Lewatit K7367) and modified resins (type Merrifield). We showed that the modified resins, lead to the oxidative cleavage of oleic acid with higher yields than commercial ones, despite the presence of solvent. However, the immobilisation of the oxodiperoxtungstate anion on commercial resins allows the one-step synthesis of acetals, compounds of great interest for the synthesis of derivatives with a high added value. Using acetone as both reagent and solvent, we obtained good yields in ketal. Furthermore, the "one-pot" acetalization reaction of oleic acid was extended to other solvents (alcohols) as an opportunity to synthesize a wide range of acetals. The developed process is particularly interesting as it leads to the direct synthesis of ketal or acetals from an unsaturated fatty acid, avoiding the intermediate reaction stepsTOULOUSE-INP (315552154) / SudocSudocFranceF

Conception de biosolvants à partir de la molécule plateforme furfural, en laboratoires virtuel et réel

TOULOUSE-INP (315552154) / SudocSudocFranceF

Fatty Acid Methyl Esters as Biosolvents of Epoxy Resins: A Physicochemical Study

The C8 to C18 fatty acid methyl esters (FAME) have been compared as solvents for two epoxy resin pre-polymers, bisphenol A diglycidyl ether (DGEBA) and triglycidyl paminophenol ether (TGPA). It was found that the solubilization limits vary according to the ester and that methyl caprylate is the best solvent of both resins. To explain these solubility performances, physical and chemical properties of FAME were studied, such as the Hansen parameters, viscosity, binary diffusion coefficient and vaporization enthalpy. Determination of the physicochemical parameters of FAME was carried out by laboratory experimentations and by calculation from bibliographic data. The Hansen parameters of FAME and epoxy resins pre-polymers were theoretically and experimentally determined. The FAME chain length showed a long dependence on the binary diffusion parameters and kinematic viscosity, which are mass and momentum transport properties. Moreover, the vaporization enthalpy of these compounds was directly correlated with the solubilization limits

Effect of fibre configurations on mechanical properties of flax/tannin composites.

Flax reinforced tannin-based composites have a potential to be used in vehicle applications due to the environmental advantages and good mechanical properties. In this paper, the effects of fibre configuration on mechanical properties of flax/tannin composites were investigated for nonwoven and woven fabric lay-up angles (UD, [0°, 90°]2 and [0°, +45°, 90°, -45°]2). The tannin/flax composites were prepared by compression moulding. The manufactured specimens were then characterized for quasi-static tensile properties, dynamic mechanical properties and low-energy impact performance. Failure mechanism was further investigated using microscopy and demonstrated the need for further adhesion improvements. The study shows that the UD fabric reinforced composite performs better in tensile strength and modulus whereas [0°, +45°, 90°, -45°]2 composite provides the best impact energy absorption performance

Recent Progress in Synthesis of Glycerol Carbonate and Evaluation of Its Plasticizing Properties

The state of the art on the glycerol carbonate (GC) synthesis has been updated since the last published reviews in 2012, 2013, and 2016. Three types of reactions continue to be studied: glycerolysis of urea, transcarbonation of DMC, DEC, or cyclic carbonates with glycerol and reaction using CO2. Among these different routes, DMC and glycerol were selected as the raw materials for the GC synthesis in this work since the transcarbonation from these green reagents leads to high yields and selectivities, using mild conditions including a less energy consuming GC separation process. Catalytic conditions using Na2CO3 seem to be a good compromise to achieve a high yield of GC, leading to an easier purification step without GC distillation. Mild temperatures for the reaction (73–78°C) as well as a low waste amount confirmed by the E-factor calculation, are in favor of controlled costs. Plasticizing properties of synthesized GC were compared to the behaviors of a commercial plasticizer and natural dialkyl carbonates, for a colorless nail polish formulation. The resulting films subjected to mechanical and thermal stresses (DMA and Persoz pendulum) showed the high plasticizing effect of GC toward nitrocellulose based films, probably due to hydrogen bond interactions between GC and nitrocellulose. The GC efficiency gives the possibility to decrease the content of the plasticizer in the formulation. Glycerol carbonate can be thus considered as a biobased ingredient abiding by the green chemistry concepts, and safe enough to be used in an ecodesigned nail polish formulation

Glycerol Acetals and Ketals as Bio-based Solvents: Positioning in Hansen and COSMO-RS spaces, Volatility and Stability towards Hydrolysis and Autoxidation

Four recently launched cyclic glycerol acetals or ketals are evaluated as bio-based solvents. Three of them are industrially available and result from the condensation of glycerol with formaldehyde, acetone and isobutyl methyl ketone. The fourth is under development and is prepared by the reaction of glycerol with benzaldehyde under heterogeneous acidic catalysis. Their solvent properties are evaluated through Hansen and COSMO-RS (COnductor-like Screening MOdel for Real Solvents) approaches, in comparison to traditional petrochemical solvents. Dioxolane- and dioxane-type isomers have close solubility parameters; however the nature of the starting aldehyde/ketone significantly impacts the solvency properties. Stability to hydrolysis depends heavily on both the aldehyde/ketone part and on the size of the ring. In acidic medium, acetals are found to be more stable than ketals and glycerol-based ketals are more stable than ethylene glycol-based ketals. In the case of benzaldehyde glycerol acetal, it is shown that the 6-member ring isomer (dioxane-type) is approximately 8 times more stable than the 5-member ring counterpart (dioxolane-type) at low pH. Stability towards autoxidation by O2 is high for formaldehyde and acetone-derived acetals and drops for the other two compounds. Glycerol acetals and ketals are promising potential alternatives to some harmful solvents such as glycol ethers and aniline

Synthesis and characterization of new polyesters based on renewable resources

A series of non-crosslinked biobased polyesters were prepared from pentaerythritol and aliphatic dicarboxylic acids, including fatty acids grafted as side-chains to the backbone of the polymer. The strategy utilized tends to create linear polymers by protecting two of the hydroxyl groups in pentaerythritol by esterification with fatty acids before the polymerization reaction. The solvent-free syntheses were performed under vacuum and catalyzed by the ion-exchange resin Amberlyst 70. The maximum yield was around 98%. Pristine polyesters had average molecular weights of about 104 g/mol according to SEC-MALLS analysis. Melting temperatures and extent of crystallinity were determined by differential scanning calorimetry. By using relatively short fatty acids, such as lauric acid, soft materials were obtained with low crystallinity and a melting point below room temperature, whereas longer side-chains, such as behenic acid, gave brittle polymers with higher melting temperatures and crystallinity. The use of a short chain dicarboxylic acid, such as succinic acid, resulted in closer side-chains and promoted higher crystallinity and melting temperatures. In order to improve the thermal properties of these materials, a series of copolyesters were designed by developing synthetic methods to approach a random- and a block-copolymerization. A wide range of properties was thus obtained according to the composition of these novel copolyesters

Management of upper gastrointestinal bleeding in emergency departments, from bleeding symptoms to diagnosis: a prospective, multicenter, observational study.

BACKGROUND: Upper gastrointestinal bleeding (UGB) is common in emergency departments (EDs) and can be caused by many eso-gastro-duodenal lesions. Most available epidemiological data and data on the management of UGB comes from specialized departments (intensive care units or gastroenterology departments), but little is known from the ED perspective. We aimed to determine the distribution of symptoms revealing UGB in EDs and the hemorrhagic lesions identified by endoscopy. We also describe the characteristics of patients consulting for UGB, UGB management in the ED and patients outcomes. METHOD: This was a prospective, observational, multicenter study covering 4 consecutive days in November 2013. Participating EDs were part of the Initiatives de Recherche aux Urgences network coordinated by the French Society of Emergency Medicine. All patients with suspected UGB in these EDs were included. RESULTS: In total, 110 EDs participated, including 194 patients with suspected UGB (median age 66 years [Q1-Q3: 51-81]). Overall, 104 patients (54%) had hematemesis and 75 (39%) melena. Endoscopy revealed lesions in 121 patients, mainly gastroduodenal ulcer or ulcerations (41%) or bleeding lesions due to portal hypertension (20%). The final diagnosis of UGB was reversed by endoscopy in only 3% of cases. Overall, 67 patients (35%) had at least one severity sign. Twenty-one patients died (11%); 40 (21%) were hospitalized in intensive care units and 126 (65%) in medicine departments; 28 (14%) were outpatients. Mortality was higher among patients with clinical and biological severity signs. CONCLUSION: Most of the UGB cases in EDs are revealed by hematemesis. The emergency physician diagnosis of UGB is rarely challenged by the endoscopic findings