Willi Kantlehner

New Guanidinium-based Room-temperature Ionic Liquids. Substituent and Anion Effect on Density and Solubility in Water

In order to examine the influence of the alkyl chain length on some physical properties of guanidinium salts, the synthesis of a homologous series of new N″-n-alkylsubstituted N,N-diethyl-N′ ,N′- di-n-propyl-N″-n-hexyl guanidinium ionic liquids (gILs), containing chloride (Cl), tetrafluoroborate (BF4), acesulfamate (Ace), saccharinate (Sac), and tosylate (Tos) as anions, is reported. Cn-gILAce, Cn-gILSac, and Cn-gILBF4 were obtained by ion exchange reaction of the corresponding hexasubstituted guanidinium chlorides (Cn-gCl, n = 3, 4, 6, 8, 10), which were synthesized by a quaternization reaction of the pentaalkyl-substituted guanidine 3 and the corresponding alkylchloride in DMF. The tosylates gILs Cn-gTos (n = 1, 2, 4, 6, 8, 10) were synthesized by alkylation of 3 with the corresponding alkyltosylates. Some physical properties, such as solubility in water and organic solvents, refractive index and density, are considered as a function of the length of the n-alkyl substituent R and the nature of the anion Graphical Abstract New Guanidinium-based Room-temperature Ionic Liquids. Substituent and Anion Effect on Density and Solubility in Water

Synthesis of Iminium Salts, Orthoesters and Related Compounds

This chapter deals with ’activated amides’, i.e. saltlike compounds, imino derivatives of carboxylic acids as well as compounds which formally arise by complete esterification or amidation of carboxylic orthoacids.

Simple Prediction of Some Physical Properties of Ionic Liquids: The Residual Volume Approach

A new method for prediction of fundamental physical properties of ionic liquids (ILs) is proposed. The Residual Volume Approach (RVA) allows the estimation of density and viscosity of unknown ILs, using a simple linear correlation between a given property and a newly defined substituent parameter βX. The proposed method has been developed for the density estimation of 50 n-alkyl-substituted imidazolium and tetraalkylammonium salts in a homologous series of ILs and has been extended for the estimation of viscosity, which also correlates linearly with the corresponding βX. In addition, the parameters βX are temperature and pressure independent, which allows the prediction of these values at any temperature and pressure Graphical Abstract Simple Prediction of Some Physical Properties of Ionic Liquids: The Residual Volume Approach

The Residual Volume Approach II: Simple Prediction of Ionic Conductivity of Ionic Liquids

The Residual Volume Approach (RVA), a recently developed method for the prediction of fundamental physical properties of ionic liquids (ILs) is extended and now allows the estimation of ionic conductivity of unknown ILs, using a simple linear correlation between the ionic conductivity and previously defined substituent parameters - βx. The proposed method is applied to the conductivity correlations of 61 n-alkyl substituted imidazolium, tetraalkylammonium, pyrrolidinium, piperidinium, sulfonium and phosphonium homologous ILs, containing [BF4]−, [Tf2 N]−, [C2 F5PF]−, [CF3BF3]−, [C2H5BF3]−, [F(HF)2.3]−, [Br]−, [I]−, and [formate]− as anions. The influence of the ion type - both anion and cation - on the property changes is discussed. Moreover, it is shown that relatively rigid cations with C2 symmetry decrease the expected conductivity in the same manner as they increase the viscosity of the ILs. Graphical Abstract The Residual Volume Approach II: Simple Prediction of Ionic Conductivity of Ionic Liquids

Beiträge zur Synthese von Orthocarbonsäureamiden

The formamidinium salts 11a, c as well as the nitrile 12 react with sodiumhydride/dimethylamine in the presence of trimethylborate to give the ortho formic acid amide 3a. The orthoamides 6a and 16 can be prepared from the iminium salts 15 and 14, resp. by the same procedure. Treatment of the azavinylogous formamidinium salt 15 with sodiumhydride and piperidine or morpholine in the presence of trime-thylborate affords the orthoamides 6c and 6d, resp. By transamination of the azavinylogous aminalester 5a are accessible the orthoamides 6b—d. The vinylogous orthocarbonic acid derivative 17 can be obtained from the salt 14 and sodium alcoholates. The action of sodiumhydride, dimethylamine and trimethylborate on the iminium salt 18 produces a mixture of the orthocarbonic acid derivatives 7a, 8a, 9a. When the guanidinium salt 20 is treated with the same reagents the ortho-amides 3a and 10a are obtained. The reduction of the salt 20 with sodiumhydride in the presence of several activating reagents (e.g. tetrabutyl orthotitanate, aluminiumisopropylate, trimethylborate) affords the orthoamide 3a. The reduction of the iminium salts 18 and 24 does not proceed clean, giving mixtures of various orthoformic acid derivatives. The form-amidine 25 can be prepared by reduction of the salt 15 with sodiumhydride/trimethylborate with good yields. By the action of the corresponding carbanions on the guanidinium salt 20 can be obtained the carboxylic acid orthoamides 26—33. By the same procedure the orthoamides of alkyne carboxylic acids 36a—h, j—n are accessible.

New Formylating Agents − Preparative Procedures and Mechanistic Investigations

The reactivity of new formylating agents related to formamide has been investigated both experimentally and theoretically. The reaction in 1,2-dichloroethane between tris(diformylamino)methane (2) and several arenes, catalyzed by AlCl3 or BCl3, was shown to proceed in good yields to afford the corresponding para-substituted aldehydes. The nature of the active electrophilic species was also investigated theoretically. Thus, the relative stability of the O- and N-protonated forms, as well as those of AlCl3 adducts, of several formylating agents − diformamide, triformamide, N,N,N′,N′-tetraformylhydrazine, and tris(diformylamino)methane − were determined in the gas phase and in water or DCE by means of DFT calculations at the B3LYP/6-311++G(d,p) level, the solvents being modeled with the IPCM method. The amide oxygen atom in all cases appeared to be the most basic site, both in the Bronsted and Lewis sense, constituting a first step towards the understanding of the mechanism of this reaction.

Empirical Polarity Parameters for Hexaalkylguanidinium-based Room-temperature Ionic Liquids

The polarity of a series of 36 hexaalkylguanidinium-based room-temperature ionic liquids (RTILs), featuring different unbranched alkyl substituents in the cation and eight different anions, has been determined by means of Reichardt’s solvatochromic betaine dye; ET(30) and the corresponding normalized ENT values are presented. The positively solvatochromic probe 5-dimethylamino-5´-nitro-2,2´-bithiophene was used to characterize unspecific solvent/solute interactions (effects of dipolarity/polarizability) of ten hexaalkylguanidinium and, for comparison, two 1-alkyl-3-methylimidazolium ionic liquids. Graphical Abstract Empirical Polarity Parameters for Hexaalkylguanidinium-based Room-temperature Ionic Liquids

2-Dimethylamino-1-(2-ethoxy-2-oxo-ethyl)-3-methyl-3,4,5,6-tetrahydro-pyrimidin-1-ium tetraphenylborate.

Isolated guanidinium ions and tetraphenylborate ions are present in the crystal structure of the title compound, C11H22N3O2 +·C24H20B−. In the guanidinium ion, the dihedral angle between the N/C/N and C/C/C planes being 49.9 (1)°. The six-membered ring exhibits a half-chair conformation. The C—N bond lengths in the cation range between 1.3335 (16) and 1.3552 (16) Å, indicating charge delocalization on the CN3 plane. In the crystal, the cations are connected by C—H⋯O hydrogen bonds, generating a chain along the c axis.

Eine neue, breit anwendbare Synthese für aromatische Aldehyde

Diformamide (1) reacts with activated aromatic compounds like toluene, anisole, m-xylene, 1,2-dimethoxybenzene in the presence of AlCl3 to give N-(diarylmethyl)-formamides 2a—d, the corresponding aromatic aldehydes 3—6 are formed as by-products in low yields. From N,N-dimethylaniline and 1/AlCl3 the triphenylmethane derivative 7 can be obtained. The reaction of anisole with N-methyl-diformamide (9) affords the formamide 10. The mixture of formamide, P4O10 and AlCl3 reveals to be a reagent which is capable to formylate toluene and anisole, resp. Triformamide (14)/AlCl3 is an effective formylating system which allows the preparation of aromatic aldehydes (e.g.3,4,17—32) from the corresponding aromatic hydrocarbons. Aluminiumchloride can be replaced by borontrichloride. The yields of the formylation reactions depend strongly from the reaction conditions (molar ratio: aromatic hydrocarbon/AlCl3/14; solvent, reaction temperature). The scope of the reaction covers nearly complete those of the Gattermann-Koch-, Gattermann- and Vilsmeier—Haack-reaction.

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 1dcan 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 4ais 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.