Synthesis and characterization of poly(ether-<Emphasis Type="Italic">block</Emphasis>-amide) copolymers/multi-walled carbon nanotube nanocomposite membranes for CO<Subscript>2</Subscript>/CH<Subscript>4</Subscript> separation

One of the effective techniques for improving separation properties of polymeric membranes is incorporation of suitable nanoparticles into their matrices. This study presents the preparation of three types of nanocomposite membranes comprising three grades of poly (ether-block-amide) (Pebax 1074, Pebax 1657 and Pebax 2533) and modified multi-walled carbon nanotubes (MWCNTs) with different loadings (1, 1.5, 2 and 2.5 wt%). The prepared membranes were characterized by field emission scanning electron microscopy (FESEM), attenuated total reflection-Fourier transfer infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD). Permeation of CO₂ and CH₄ gases through the prepared membranes was measured at the pressure range of 2-8 bars and 25 °C. The results showed that the incorporation of MWCNTs into the polymers matrices improves CO₂/CH₄ selectivity. Further, Pebax 1074/MWCNT nanocomposite membrane exhibits better performance for CO₂/CH₄ separation compared to the neat Pebax and the two other nanocomposite membranes.     

Synthese substituierter 2-Nitrophenylhydrazone von 2-Oxodicarbonsäureestern und Untersuchung ihres Tautomerie- und Absorptionsverhaltens

Synthesis of Substituted 2-Nitrophenylhydrazones of 2-Oxodicarboxylic Acid Esters and Investigation of Their Tautomerism and Absorption Behaviour 32 Substituted 2-nitrophenylhydrazones of diethyl oxalacetate, 2-oxoglutaric acid and its 1-mono- and 1,5-dialkyl esters, resp., have been synthesized from substituted 2-nitrophenylhydrazines and 4,6-dinitro-1,3-dihydrazinobenzene and the carbonyl compounds named above. ¹H-n.m.r. spectra prove all products to have the constitution of hydrazones and not that of azo compounds or enhydrazines and also allow the assignation of the E- and Z-configuration, resp., to the hydrazone diastereomers. The absorption behaviour of all hydrazones is discussed with comparison of the different substitution patterns. Unexpectedly, the 4,6-dinitro-1,3-bishydrazones 27 – 32 show very high lg ϵ_max values (at about 4.8) due to their crossed two chromophoric systems.     

Cycloadditionen. 23 [1]. Zur Thermischen Reaktivität von S-(1-Naphthyl)- und S-(9-Anthryl)-2-methyl-buta-2,3-dienthiosäureestern

Cycloadditions. 23. The Thermal Reactivity of S-(1-Naphthyl) and S-(9-Anthryl)2-methyl-2,3-butadienethioates Heating of the S-(1-naphthyl)esters of 2-methyl-2,3-butadiene thioacid and of 2-methyl-4,4-diphenyl-2,3-butadiene thioacid ( 3a resp. 3b ) furnishes mixtures of the Diels-Alder products 5a, b and the cyclobutenone 7 and the naphthol derivative 8 , resp. The corresponding S-(9-anthryl) esters 4a, b are not isolable; under the conditions of their synthesis (allenecarboxylic acids 1a u. b , 9-thioanthrol 2b , DCC and DMAP) they isomerise spontaneously to the Diels-Alder products 9 .     

Structure-activity relations of β-adrenergic agents

A review of the structure-activity relations in aryloxypropanolamine β-adrenoceptor drugs is presented. The effect of substitution in various parts of the molecule on β₁/β₂ selectivity and degree of partial agonism is discussed. Cardiac (β₁) selectivity is achieved by hydrophilic compounds with either p-amide substitution in the aryl ring, or a hydrogen bonding group in the amine side chain. Lipophilic compounds with branched chains tend to be β₂ selective. Partial agonist activity may also be controlled by hydrogen bonding groups in the side chain and by aromatic substitution. Here 3,4-dihydroxyl groups give full agonists, mono-and des-hydroxy (OH) groups partial agonists. The size of any o-substituent is critical and a plot of Taft's steric factor versus partial agonism gives a linear relation. By manipulation of the above factors all combinations of selectivity and agonist activity may be achieved.     

Diels‐Alder‐Adducts of Dichloromethylenepropanedinitrile; Reactions with Nucleophiles

Upon treatment with aqueous alkali, the Diels—Alder adducts 2 and 4 of dichloromethylenepropane‐dinitrile ( 1 ) with cyclopentadiene and anthracene resp. are converted into 3‐chloro‐bicyclo[2.2.1]hepta‐2,5‐diene‐2‐carbonitrile ( 3 ) and 12‐chloro‐9,10‐dihydro‐ethenoanthracene‐11‐carbonitrile ( 5 ), resp. The reaction may be brought about by other nucleophiles as well and involves the fragmentation of an intermediate β‐chloroimidate anion. 3 is a educt for substituted norbornenes such as cyanoketone 18 .     

Orthoamide. LI. Push-Pull-Butadiene und Heterocyclen aus CH2-aciden Verbindungen und Orthoamiden von Alkincarbonsäuren

Orthoamides. LI. Push-Pull-Butadienes and Heterocycles from Alkyne Carboxylic Acid Orthoamides and CH₂-acidic Compounds The acetylides 4b, 4f react with N,N,N′,N′,N″,N″-hexamethylguanidiniumchloride ( 5 ) to give the orthoamides 6b, 6f , resp. From CH₂-acidic compounds and the orthoamides 6a, c, e can be obtained the push-pull-substituted butadienes 8a–8aj . The 2,3,5-trimethyl-thiadiazolium salt 9 does not condense with 6e , as other CH₂-acidic compounds do, instead the vinylogous guanidinium salt 10a is produced. On heating, the ketenaminals 8d, aa cyclize to give the pyridone-carbonitriles 11a, b , resp. From 4-amino-coumarins 12 and the orthocarboxylic acid amideacetals 13a, b and the ketenaminal 16 resp., the amidines 14a–c and the heterocyclic compounds 15a–c resp., are formed. The enamines 17a–c, 19a, b react with the orthoamides 6a–f to give the pyridine derivatives 18a–1, 20a–h and 21a, b , resp. Analogously, from 6-aminouracil 22 and 6a, b, e, f are formed the pure 7-dimethylaminopyrido[2,3-d] pyrimidines 23a, b or mixtures of compounds 23c, d and the isomeric 4-dimethylamino-pyrido[2,3-d]pyrimidines 24a, b resp., which can be separated via their salts 25a,b/26a,b . The heterocyclic compounds 30a–d, 32a,b can be prepared from the pyrazole derivatives 28, 31 resp. and the orthoamides 6a–f .     

Synthesen auf der Basis von 2-Oxoglutarsäure. II Zur Synthese von Heterocyclen durch Reaktionen von 3-Brom-2-oxoglutarsäuredimethylester mit Binucleophilen

Organic Syntheses Based on 2-Oxoglutaric Acid. II. On the Synthesis of Heterocycles by Reactions of Dimethyl 3-bromo-2-oxoglutarate with Binucleophiles Reactions of dimethyl 3-bromo-2-oxoglutarate 2 with binucleophiles to form heterocycles proceed on two different pathways depending on the type of reactant. Thus, strong S-nucleophiles like thioureas and thiocarbohydrazide substitute initially the bromine atom and form 2-aminothiazoles 3 – 7 and the 1,3,4-thiadiazine 8 . However, o-phenylendiamines reacted to form the brominated quinoxaline-2(1H)-one derivatives 9 and 10 , resp.     

Orthoamide. LIV [1] Beiträge zur Chemie azavinyloger Orthoamid‐Derivate der Ameisensäure

Orthoamides. LIV. Contributions to the Chemistry of Azavinylogous Orthoformic Acid Amide Derivatives The azavinylogous aminalester 3 reacts with primary amines to give amidines 5 and 6 . In the reaction of 3 with aniline the azavinylogous amidine 7 is produced additionally to the amidine 5c . Ethylendiamine is formylated at both aminogroups, the bis‐amidine 8 thus formed is transformed to the salts 9a , b . Benzoxazole and benzimidazole can be prepared from 3 and o‐aminophenol and o‐phenylenediamine, resp. carboxylic acid amides, urea, thiourea, aromatic acid hydrazides 17 and the sulfonylhydrazide 19 are formylated by 3 at nitrogen to give N‐acylated formamidines 14 , 16 , 18 , 20 . From 3 and aliphatic acid hydrazides 17 and alkylhydrazines, resp., can be obtained 1,2,4‐triazole 21 and 1‐alkyl‐1,2,4‐triazoles 22a , b , resp. N,N‐dimethylcyanacetamide ( 32 ) reacts with 3 and the orthoamide 4a , resp., to give a mixture of the formylated compound 34 and the amidine 33 . The reaction conditions are of low influence on the ratio in which 33 and 34 are formed. The orthoamide 4b and 32 react to afford a mixture of the amidine 35 and the enamine 36 . Hydrogensulfide acts on 3 giving N,N‐dimethylthioformamide ( 37 ). From 3 and 1‐alkynes 41 can be prepared the amidines 42 . Hydrolysis of 42b affords phenylpropiolaldehyde ( 43 ). The alkylation of the aminalester 3 gives rise to the formation of vinylogous amidiniumsalts 1c and 1d , resp., additionally is formed the amide acetal 2a . The salt 1d can also be prepared from 3 and borontrifluoride‐ether. Iodide reacts with N,N‐dimethylformamide acetals 12a , b in an unclear, complicated manner giving orthoesters 53 , N,N‐dimethylformamide, alkyliodides, alcohols, ammoniumiodides 46 and carbondioxide. The action of halogens on 3 affords the salts 1a , b , c , e , f depending on the chosen stoichiometric ratio. Aromatic aldehydes are suited for trapping azavinylogous carbenes formed on thermolysis of 3 — 1,3‐oxazoles 69 are the reaction products. From 3 and propionaldehyde the amidine 65 can be obtained with low yield. Carbondisulfide transforms 3 to the azavinylogous salt 66 . The preparation of the azavinylogous orthoamide 4a is described. The thermolysis of 3 and 4a , resp., gives rise to the formation of the triaminopyrimidine 67 . Treatment of 1a with lithiumdiisopropylamide affords the triaminopyrazine 68 , which can also be obtained by thermolysis of 3 in the presence of sodium hydride. Azavinylogous carbenes are thought to be the intermediates.     

LINK Synthesis with 3-Hydroxy-1H-pyrazoles: 3-Carboxyisoalkyloxy-1H-pyrazoles – bicyclic acylpyrazolium salts and γ-Lactams – 3-Carboxyisoalkyloxy-4,5-dihydro-1H-pyrazol-5-ones

1-Substituted 3-hydroxy-1H-pyrazoles 1 react with chloroform, NaOH, and aceton resp. butan-2-one O-regiospecifically to yield 2-methyl-2-[(1H-pyrazol-3-yl)oxy]-propanoic resp. -butanoic acids 14 via a dichlorocarbene ( 12 )–dichlorooxirane ( 9 ) pathway. Chlorides 17 of 14 easily cyclize to N-acylpyrazolium salts 18/19 , which quantitatively afford esters 22–26 and amides 27–29 of 14 . Enantiomers of the butanoic acid 14th , obtained via their diastereomeric cholesterol esters, differ in their stimulus to peroxisome proliferation. At 140 °C pyrazolium salts 18 undergo thermolysis to bicyclic β-oxa-γ-lactams 30–32 . 3-Carboxyisoalkylamino-pyrazoles similarly give 1H-β-aza-γ-lactams 34 . Reactions of 14 with surplus SOCl₂ result in 6-chloro- 37 resp. 7-chloro-β-oxa-γ-lactams 38 via chlorosulfinylation and extrusion of SO, and in 4,4-bispyrazolyl-sulfoxide 39 . A mild introduction of additional O-functions into pyrazoles affording 4,5-dihydro-3-hydroxy-5-oxo-1H-pyrazoles 52–57 is presented. Biological effects of the new pyrazoles are protection against shock and ADP-induced thromboembolism, reduction of serum lipids and improvement of blood flow.     

Darstellung und Reaktionen von α-Halogenbenzyl-silanen

Preparation and Reactions of α-Halogenobenzyl-silanes α-Bromobenzyl-dimethylchlorosilane 3 , bis-(α-bromobenzyl)-dimethylsilane 8 and the corresponding α-chlorobenzyl-compounds 5 and 13 have been prepared by reaction of benzyl-dimethylchlorosilane 1 resp. dibenzyl-dimethylsilane 2 with N-bromosuccinimid and sulfurylchlorid. The α-halogenobenzyl-dimethylchlorosilanes 3 and 5 have been treated with water, alcohols and phenol, to give the corresponding silanols 15 and 16 , siloxanes 17 and 18 , alkoxy- and phenoxysilanes 19 and 20 . Reactions of 3 with brenzcatechin, o-aminophenol and o-aminobenzylalcohol give 6- resp. 7- membered silaheterocycles 21 – 23 .     

Preparation and properties of 2-Dialkylamino-5-haloacetyl-thiazoles and 4-(2-Dialkylamino-5-thiazolyl)-thiazoles

By the reaction of N-acylthioureas 7 with 1,3-dichloroacetone 9 2-dialkylamino-5-chloroacetyl-thiazoles 11 are available. These compounds react with thioureas or arylthioamides under heterocyclisation to give bis-(2-dialkylamino-5-thiazolyl)-ketones 13 , 2-aryl-4-(2-dialkylamino-5-thiazolyl)-thiazoles 14 , or 2-dialkylamino-4-(2-dialkylamino-5-thiazolyl)-thiazoles 15 , resp., from which the last-mentioned compound exhibit a high reactivity towards several electrophilic reagents. Thus, deeply colored cyanovinyl, arylazo, and arylmethine substituted bisthiazole dyes 17, 18 , and 19 , resp., have been formed.     

Mischungsfunktionen im binären System N-Methylcaprolactam – n-Tetradecan

Mixing Functions of the Binary System N-Methylcaprolactam – n-Tetradecane The liquid-liquid equilibria(LLE) and the vapour-liquid equilibria(VLE) at 60°C were measured in the binary system N-methylcaprolactam (1) – n-tetradecane (2). The enthalpy of mixing H^E of the same system was extrapolated from H^E – measurements of N-methylcaprolactam with other alkanes. The limiting activity coefficients f_∞1 and f_∞2 were obtained by extrapolation from values of resp. in other alkanes. For a comparison the vapour pressures of the mixture were calculated by model equations with constants from the two limiting activity coefficients and with temperature dependent constants extracted from the LLE and H^E measurements.     

Derivate des Phosphorsäure-o-phenylenesters. XVI. o-Phenylendioxyphosphonium-hexahalogenoantimonate

Derivatives of o-Phenylenphosphates. XVI. o-Phenylendioxyphosphonium-hexahalogenoantimonates Pentacoordinated o-phenylen-orthophosphate-trihalogenides 1 resp. bis-o-phenylenorthophosphate-chloride 3 can be transformed to stable quasiphosphoniumsalts 2 resp. 4 by reaction with SbCl₅ or SbBr₃/Br₂. The structures of 2 and 4 are confirmed by ³¹P-n.m.r.     

Organoarsen-Verbindungen. XXVIII [1]. Reaktionen 2-aminofunktioneller Arsine mit Acetylenen

Organo-arsenic Compounds. XXVIII. Reactions of 2-Aminofunctional Arsines with Acetylenes Phenylacetylene and isopropenylacetylene add secondary 2-aminoethylarsines or o-aminophenylarsines to give mixtures of the cis- and trans-styrylarsines and of the trans-4,3-(90%) and 4,1-adducts (10%) to the enine, resp. ¹H-n.m.r.-and i.r.-data of the compounds are recorded.     

Searching for health beneficial n‐3 and n‐6 fatty acids in plant seeds

Various plant seeds have received little attention in fatty acid research. Seeds from 30 species mainly of Boraginaceae and Primulaceae were analysed in order to identify potential new sources of the n‐3 PUFA α‐linolenic acid (ALA) and stearidonic acid (SDA) and of the n‐6 PUFA γ‐linolenic acid (GLA). The fatty acid distribution differed enormously between genera of the same family. Echium species (Boraginaceae) contained the highest amount of total n‐3 PUFA (47.1%), predominantly ALA (36.6%) and SDA (10.5%) combined with high GLA (10.2%). Further species of Boraginaceae rich in both SDA and GLA were Omphalodes linifolia (8.4, 17.2%, resp.), Cerinthe minor (7.5, 9.9%, resp.) and Buglossoides purpureocaerulea (6.1, 16.6%, resp.). Alkanna species belonging to Boraginaceae had comparable amounts of ALA (37.3%) and GLA (11.4%) like Echium but lower SDA contents (3.7%). Different genera of Primulaceae (Dodecatheon and Primula) had varying ALA (14.8, 28.8%, resp.) and GLA portions (4.1, 1.5%, resp.), but similar amounts of SDA (4.9, 4.5%, resp.). Cannabis sativa cultivars (Cannabaceae) were rich in linoleic acid (57.1%), but poor in SDA and GLA (0.8, 2.7%, resp.). In conclusion, several of the presented plant seeds contain considerable amounts of n‐3 PUFA and GLA, which could be relevant for nutritional purposes due to their biological function as precursors for eicosanoid synthesis. Practical applications: N‐3 PUFA are important for human health and nutrition. Unfortunately, due to the increasing world population, overfishing of the seas and generally low amounts of n‐3 PUFA in major oil crops, there is a demand for new sources of n‐3 PUFA. One approach involves searching for potential vegetable sources of n‐3 PUFA; especially those rich in ALA and SDA. The conversion of ALA to SDA in humans is dependent on the rate‐limiting Δ6‐desaturation. Plant‐derived SDA is therefore a promising precursor regarding the endogenous synthesis of n‐3 long‐chain PUFA in humans. The present study shows that, in addition to seed oil of Echium, other species of Boraginaceae (Cerinthe, Omphalodes, Lithospermum, Buglossoides) and Primulaceae (Dodecatheon, Primula), generally high in n‐3 PUFA (30–50%), contain considerable amounts of SDA (5–10%). Therefore, these seed oils could be important for nutrition.     

3-α-Bromacetyl-cumarine als Synthesebausteine für Heterocyclisch substituierte Cumarine

3-α-Bromacetyl-coumarines as Synthones for Heterocyclic Substituted Coumarines 3-α-Bromacetyl-coumarines 2 react easily and in high yields with thiourea and thioamide derivatives 3 and 5 , resp., to 4-coumar-3′-yl-thiazoles 4 and 6 , resp., as well as with N,N-disubstituted thioamides 11 and N,N,N′,N′-tetraalkylthiourea 12 to 5-coumar-3′-yl-oxathioliumsalts 13 and 14 , respectively. In a two-step reaction 2 can be transformed by reaction with aniline 17 to 4-coumar-3′-yl-imidazoles 21 and 5-coumar-3′-yl-oxazoliumsalts 22 , resp., via aminoketone intermediates 18 .     

Die Reaktion von α,β-Dihalogen-propionitrilen mit monosubstituierten Hydrazinen - einfache Synthese 1-substituierter 3- bzw. 5-Amino-pyrazole

The Reaction of α,β-Dihalogeno-propionitriles with Monosubstituted Hydrazines — A Simple Synthesis of 1-Substituted 3- or 5-Amino-pyrazoles In methanol hydrazines 3 , and α,β-dihalogeno-propionitriles 1, 2 even at 0°C irreversibly yield 3 · HX, and α-halogenoacrylonitriles 4, 5 (A₁). Fast addition of alkyl- and aralkyl- hydrazines 3 to 4, 5 (C) gives 1-substituted 1-(2′-halogeno-2′-cyan-ethyl)-hydrazines 6 , the addition of arylhydrazines 3 to 4, 5 (D) 1-aryl-2-(2′-halogeno-2′-cyan-ethyl)-hydrazines 8 . In methanol 6 spontaneously cyclise (E) to hydrogen halides 7 · HX of 1-alkyl- and 1-aralkyl-3-amino-pyrazoles, 8 with 2 moles of acids (F) to salts 10 · 2HY of 1-aryl-4-halogeno-5-imino-pyrazolidines, and the free 10 spontaneously (G) to hydrogen halides 9 · HX of 1-aryl-5-amino-pyrazoles. Mechanisms (A₁), (C), (D), (E), (F), and (G) are proved by t.l.c., ¹H-n.m.r., and isolation of intermediates, the structures of 7 resp. 9 , using the significant ¹H-n.m.r.-parameter Δ. Simple general syntheses are described for 3-amino-pyrazoles 7 (R = H, alkyl, aralkyl) or 5-amino-pyrazoles 9 (R = aryl) starting with α,β-dihalogeno-propionitriles 1, 2 , and for α-bromo-acrylonitrile 5 .     

Modeling vapor–liquid equilibrium and liquid–liquid extraction of deep eutectic solvents and ionic liquids using perturbed-chain statistical associating fluid theory equation of state. Part II

This study aims to use perturbed-chain statistical associating fluid theory (PC-SAFT) to describe the phase behavior of systems containing deep eutectic solvents (DESs) and ionic liquids (ILs). The DESs are based on tetrabutylammonium chloride and tetrabutylammonium bromide as hydrogen bond acceptors, and levulinic acid and diethylene glycol as hydrogen bond donors in the mole ratio of 1:2 and 1:4, respectively. Predictions of phase equilibria by PC-SAFT were compared with the results of COnductor like Screening MOdel for Real Solvents (COSMO-RS) and non-random two-liquid (NRTL). In this work, low viscosity ether- and pyridinium-based ILs [E_nPy][NTf₂] and [C_mPy][NTf₂] were used for vapor–liquid equilibrium systems, while 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-amide and 1-propyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide with n-heptane + thiophene and n-hexane + ethylbenzene were used in the liquid–liquid extraction, respectively. In the last part, the phase behavior of the mixtures of perfluoroalkylalkanes with their linear alkane counterparts was studied and compared with the SAFT-Mie pair potential.     

Effects of low and high molecular mass PEG incorporation into different types of poly(ether-<Emphasis Type="Italic">b</Emphasis>-amide) copolymers on the permeation properties of CO<Subscript>2</Subscript> and CH<Subscript>4</Subscript>

Blend membranes were prepared by incorporating two types of polyethylene glycol (PEG) (molecular masses of 400 and 1000 g mol^?1) into three grades of poly(ether-block-amide) (PEBAX), namely PEBAX 1074, PEBAX 1657, and PEBAX 2533. The PEGs, which were used as blending agents, were employed at mass fractions ranging from 10 to 40 wt.% based on the mass of PEBAX. The gas separation performance of each neat or blend membrane, comprising its CO₂ and CH₄ permeabilities and its ideal CO₂/CH₄ selectivity, was studied at room temperature (25 °C) and at pressures of 2–8 bar. X-ray diffraction (XRD) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) analyses were used to determine the crystallinities of and the chemical bonds in the prepared membranes, respectively. Scanning electron microscopy (SEM) was also utilized to observe the morphologies of the membranes. The results obtained from experimental investigations showed that the incorporation of low molecular mass PEG significantly increased the permeability but only slightly affected the ideal CO₂/CH₄ selectivity, while the incorporation of high molecular mass PEG decreased the permeability considerably but sharply increased the ideal CO₂/CH₄ selectivity. This behavior intensified as the polyether content of the PEBAX was decreased.

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Graphical abstract

     

Synthesis and Characterization of 1‐Azido‐2‐Nitro‐2‐Azapropane and 1‐Nitrotetrazolato‐2‐Nitro‐2‐Azapropane

1‐Azido‐2‐nitro‐2‐azapropane ( 1 ) was synthesized in high yield from 1‐chloro‐2‐nitro‐2‐azapropane and sodium azide. 1‐Nitrotetrazolato‐2‐nitro‐2‐azapropane ( 2 ) was synthesized in high yield from 1‐chloro‐2‐nitro‐2‐azapropane and silver nitrotetrazolate. The highly energetic new compounds ( 1 and 2 ) were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁴N), elemental analysis and low‐temperature single crystal X‐ray diffraction. 1‐Azido‐2‐nitro‐2‐azapropane ( 1 ) represents a covalently bound liquid energetic material which contains both a nitramine unit and an azide group in the molecule. 1‐Nitrotetrazolato‐2‐nitro‐2‐azapropane ( 2 ) is a covalently bound room‐temperature stable solid which contains a nitramine group and a nitrotetrazolate ring unit in the molecule. Compounds 1 and 2 are hydrolytically stable at ambient conditions. The impact sensitivity of compound 1 is very high (<1 J) whereas compound 2 is less sensitive (<6 J).