Vapor–liquid equilibria of the binary mixtures formed by nitromethane with five alkyl alkanoates at 101.3 kPa

Vapor–liquid equilibria were measured at 101.3 kPa, in a range of temperatures from 350.28 to 374.69 K, for five binary mixtures formed by nitromethane with ethyl acetate, propyl acetate, isopropyl acetate, methyl propionate, and ethyl propionate. Calculations of nonideality of the vapor phase were made with Soave–Redlich–Kwong equation of state. Thermodynamic consistency of data was tested via Herington analysis. Two systems show minimum boiling azeotropes. The experimental VLE data were reduced and binary parameters for four liquid models, such as van Laar, Wilson, NRTL and UNIQUAC, were fitted. A comparison of model performances was made by using the criterion of average absolute deviations in boiling point and in vapor-phase composition.     

Chlorolysis of β-functionalized alkyl polyfluoroalkenyl sulfides

Chlorolysis of -functionalized alkyl polyfluoroalkenyl sulfides giving rise to -functionalized polyfluoroalkenesulfenyl chlorides was examined. -Cyano-containing sulfenyl chlorides underwent intramolecular cyclization at the nitrile group to form substituted isothiazoles.     

A convenient one-pot preparation of methylα-aryl-β-primarylamino alkanoates

Six examples of -aryl- primarylamino esters (V) were synthesized by a convenient one pot methodology, i.e., reaction of lithiated methyl -aryl-acetates with 1-(triphenylphosphoroylideneaminomethyl)benzotriazole (BETMIP) followed by hydrolysis.Center for Heterocyclic Compounds, Department of Chemistry, University of Flo rida, Gainesville, Florida 32611–7200, USA. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1023–1025, August, 1995. Original article submitted July 3, 1995.Submitted in honor of the 60th anniversary of Professor Nikolai S. Zefirov, an outstanding Russian chemist and a good friend. by Alan R. Katritzky.     

A simple method of obtaining σ values of alkyl substituents

The Taft's σ value of any given alkyl substituent can be calculated from the equation σ = −0.255 σ_b + 0.461 since the value of σ_b, an alkyl substituent constant, of any alkyl group can be obtained from the CC and CH bond refractions.     

Electrochemically promoted decarboxylative borylation of alkyl N-hydroxyphthalimide esters

An electrochemically promoted decarboxylative borylation reaction is reported. The reaction proceeds under mild conditions in an undivided cell without use of transition metal-or photo-catalysts. The key feature of the reaction is the compatibility of diboron reagents with the electrochemical conditions. This reaction exhibits broad substrate scope, good functional group tolerability, and easy scalability.     

Electrochemically promoted decarboxylative borylation of alkyl N-hydroxyphthalimide esters

An electrochemically promoted decarboxylative borylation reaction is reported. The reaction proceeds under mild conditions in an undivided cell without use of transition metal-or photo-catalysts. The key feature of the reaction is the compatibility of diboron reagents with the electrochemical conditions. This reaction exhibits broad substrate scope, good functional group tolerability, and easy scalability.     

Enumeration of isomers of alkylcyclopropanes by means of alkyl 1,1‐biradicals

Henze and Blair [2] have successfully derived algorithms for enumerating the number of constitutional isomers of aliphatic compounds using alkyl radicals; however, the algorithms cannot be extended to enumerate constitutional isomers of cyclic compounds. Similarly, Read [4] has advocated the use of alkyl biradicals to enumerate constitutional isomers of aliphatic compounds, but not cyclic compounds. Apparently, the use of alkyl biradicals in the enumeration of constitutional isomers of cyclic compounds has been neglected. In this communication, an algorithm using alkyl biradicals to enumerate the number of constitutional isomers of cyclic compounds, namely alkylcyclopropanes, is described. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reaction of alkyl 3-bromo-3-nitroacrylates with substituted hydrazines. Synthesis of N′-substituted alkyl 3-nitropyruvate hydrazones

Russian Chemical Bulletin - The reaction of alkyl 3-bromo-3-nitroacrylates with substituted phenylhydrazines and hydrazides of aromatic acids proceeds through the formation of aza-Michael adducts....     

Base cleavage of α-halosubstituted alkyl groups from germanium

A kinetic study has been made of the base cleavage of di- and trihalomethyl(trimethyl)germanes (Me₃GeCHX₂, Me₃GeCX₃; X = Cl, Br) in n-propanol/water in the presence of ammonia buffer. Two processes leading to the GeC bond cleavage were detected, and their rate constants were determined. The results for the dihalomethyl(trimethyl)germanes are compared with those for the corresponding processes at silicon and tin centres.     

Blends of poly(∈-caprolactone) with cellulose alkyl esters: effect of the alkyl side-chain length and degree of substitu tion on miscibility

Cellulose alkyl esters, CELL- OCOCnH2n+1(n = 1 6), were synthesized by a homogeneous reaction of cotton cellulose with different acyl chlorides in N,N-dimethylacetamide--lithium chloride solution. The miscibility of the esterified celluloses with poly(-caprolactone) (PCL) was investigated, mainly through thermal analysis by differential scanning calorimetry (DSC). A polymer pair, cellulose butyrate (CB)/PCL, showed the highest miscibility of all the binary blends examined here; this is usual when relatively high-substituted esters (DS 2.0) are used as the respective component. The butyl ester derivatives with DS 1.5 showed poor miscibility with PCL     

Metal-free synthesis of amphiphilic functional polycarbonates

Amphiphilic block copolymers of poly(5-benzyloxy trimethylene carbonate)(PBTMC) and poly(ethylene glycol)(PEG) were synthesized through enzymatic polymerization using immobilized porcine pancreas lipase(IPPL).The obtained copolymers with different compositions were characterized by GPC and ~1H NMR.The copolymer composition was in agreement with the feed ratio. The molecular weight of the copolymers showed an increasing trend with the decrease of PEG contents.Micelles of the copolymers were formed by dialysis procedure,and characterized by transmission electron microscopy (TEM).     

Metal-flee synthesis of amphiphilic functional polycarhonates

Amphiphilic block copolymers of poly（5-benzyloxy trimethylene carbonate） （PBTMC） and poly（ethylene glycol） （PEG） were synthesized through enzymatic polymerization using immobilized porcine pancreas lipase （IPPL）. The obtained copolymers with different compositions were characterized by GPC and IH NMR. The copolymer composition was in agreement with the feed ratio. The molecular weight of the copolymers showed an increasing trend with the decrease of PEG contents. MiceUes of the copolymers were formed by dialysis procedure, and characterized by transmission electron microscopy （TEM）.     

Rh(Ⅰ)-catalyzed borylation of primary alkyl chlorides

Rhodium-catalyzed cross-coupling reactions of unactivated primary alkyl chlorides with diboron reagents have been developed as practical methods for the synthesis of alkylboronic esters. These reactions expand the concept and utility of Rh(I)-catalyzed cross-coupling of aliphatic electrophiles.     

Thiazolium-catalyzed intermolecular Stetter reaction of linear and cyclic alkyl α-diketones

An efficient method for the N-heterocyclic carbene (NHC)-catalyzed conjugate addition of acetyl anions to various α,β-unsaturated acceptors (Stetter reaction) has been optimized by using 2,3-butandione (biacetyl) as an alternative surrogate of acetaldehyde. The disclosed procedure proved to be compatible with microwave dielectric heating for reaction time reduction and with the use of different linear α-diketones as acyl anion donors (e.g. 3,4-hexanedione for propionyl anion additions). Moreover, the unprecedented umpolung reactivity of cyclic α-diketones in the atom economic nucleophilic acylation of chalcones is herein presented. Mechanistic aspects of the thiazolium-based catalysis involving linear and cyclic α-diketone substrates are also discussed.     

Chromatography–mass spectrometry determination of alkyl methylphosphonic acids in urine

The potentials of different chromatography–mass spectrometry methods for the determination of alkyl methylphosphonic acids (AMPAs)—the chemical markers of nerve agents in urine—are compared. The gas chromatography–mass spectrometry (GC–MS) characteristics of various volatile AMPA derivatives are studied. The preference of perfluorobenzyl derivatives over methyl, trimethylsilyl and tert-butyldimethylsilyl esters for the GC–MS determination of AMPAs in urine is demonstrated. An optimal technique for the determination of AMPAs in urine is HPLC combined with high-resolution MS² mass spectrometry with the isotope–labeled forms of target compounds as internal standards. The detection limits of AMPAs in the proposed analytical procedures vary from 0.1 to 1.0 ng/mL.     

An efficient synthesis of substituted alkyl acrylates using α-keto amides

The addition of α-keto amides as a NH-acid to alkyl propiolates and dialkyl acetylenedicarboxylates in the presence of a catalytic amount of triphenylphosphine gives the corresponding substituted alkyl acrylates.