Protonation susceptibility of functional groups: A new parameter for interpreting chemical ionization mass spectra of bifunctional organic compounds

A new parameter, the protonation susceptibility (PS), of functional groups in the chemical ionization mass spectrometry of bifunctional organic compounds is presented. In terms of quasi-equilibrium theory of unimolecular decomposition of the molecular protonated ion of [MH]⁺, the relative PS corresponds to the relative area under P(E) curves of [MH]⁺ ions that have a proton at different functional groups. Numerical evaluation of the PS values of pertinent functional groups was made by using particularly selected compounds. The results clearly indicate that PS is independent of proton affinity (PA).     

The synthesis and morphology of grafted semiinterpenetrating polymer networks on the basis of functional prepolymers

Semi-IPNs on the basis of PU prepolymers with carboxylic groups and methacrylic copolymers with tertiary amine groups were synthesized. The influence of the functional group content and of the M_n of polymer components, as well as their ratio, on the morphology and mechanical properties were investigated. The miscibility in the systems was estimated by differential scanning calorimetry (DSC) and by scanning electron microscopy (SEM). The miscibility of components was increased by augmenting the content of the functional groups. By varying the ratio of components, the highest miscibility was found at the isoelectric ratio of functional groups. However, all the investigated IPNs were two-phase systems, due to the segmented structure of PU prepolymers. The lowering of M_n values of the starting components did not improve their compatibility. The mechanical properties of semi-IPNs changed with the increased concentration of functional groups in a way that is typical for ionomers. By physical interactions between functional groups, Young's modulus was most influenced, while the M_n of the polymethacrylic component influenced the tensile strength of IPNs. The compatibility between PU hard segments and the polymethacrylic component found in our experiments led us to the conclusion that the preparation of IPNs of finer morphology would be possible by using PU prepolymers with shorter soft segments. © 1996 John Wiley & Sons, Inc.     

Towards physical interpretation of Hammett constants: charge transferred between active regions of substituents and a functional group

The charges transferred between substituents and two functional groups: nitroso and N,N-dimethylamine in disubstituted benzene rings, were calculated at the B3LYP/cc-pVDZ level, using Natural Population Analysis. They were compared with the charges transferred between active regions of the substituents and of the groups. The transferred charge was well correlated with the Hammett constants, but only when the charges were calculated for the corresponding active regions instead of being calculated for the substituents and functional groups themselves. The results were compared for substituents introduced at the para and meta position to the NO and N(CH₃)₂ groups.     

Effect of chemical structure in photochromic polymers of the mercury thiocarbazonate series

The effects of the chemical structure of the functional portion as well as the comonomer composition on the photochromic behavior of vinyl polymers containing mercury thiocarbazonate functional groups in the side chains were investigated. It was found that, for p-acrylamidophenyl mercuric thiocarbazonate polymers, the uses of β-naphthyl and strongly electron-releasing p-methoxyphenyl groups for the thiocarbazone residue provide absorption maxima shifted somewhat to longer wavelengths as compared with the use of unsubstituted phenyl groups, whereas the electron-withdrawing o-trifluoromethylphenyl group brings about much larger shifts towards shorter wavelengths, the o-trifluoromethylphenyl group and those groups capable of exerting steric hindrances such as β-naphthyl and o-methylphenyl groups causing slower light and dark reactions too. The increase of free volumes in the polymers by regulating the comonomer composition, i.e., the lowering of T_g, was found to improve photochromic responses strikingly.     

Thermal stability of high-energy compounds

The influence of molecular structure on the stability of high-energy compounds is considered. The kinetic parameters of the decomposition of various energy-rich groups in monofunctional compounds are established. Data on decomposition of compounds with mixed functional groups are described. The sites of primary breakdown are determined and the mutual influence of functional groups on the stability is considered. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 231–234, February, 2000.     

Structure elucidation with lanthanide-induced shifts 5. Evaluation of the binding ability of various functional groups

The equilibrium binding constants have been evaluated for the association in CCl₄ of the lanthanide shift reagent. Eu(fod)₃, with a series of adamantane derivatives containing a variety of different functional groups. It is shown that if steric effects are held constant the binding abilities of the adamantane derivatives exhibit a good correlation with the proton affinities of the methyl analogs containing the same functional groups. The results permit the prediction of binding strength of other functional groups with Eu(dpm)₃ as well as with Eu(fod)₃ and thus can be of great assistance in planning and interpreting the results of experiments with lanthanide shift reagents.Part 4:D. J. Raber, M. D. Johnston, jr., C. M. Campbell, C. M. Janks, andP. Sutton, Org. Mag. Res.11, 323 (1978).     

Selective polymerization of functional monomers with Novozym 435

Two novel monomers, ambrettolide epoxide and isopropyl aleuriteate, encompassing functional groups, were obtained in a single step from commercially available materials. Novozym 435 catalyzed ring opening polymerization of ambrettolide epoxide furnished a polymer of M_n = 9.7 kg/mol and PDI = 1.9 while the epoxide groups remained unaffected during the polymerization. Selective polymerization of the primary hydroxyl groups of isopropyl aleuriteate using Novozym 435 was feasible and a polymer with moderate molecular weight (M_n = 5.6 kg/mol, PDI = 3.2) was isolated in moderate yield (43%). Subsequently, copolymerization of isopropyl aleuriteate with ε‐CL in different ratios was performed, resulting in soluble, hydroxy functional polymers with good molecular weights (M_n = 10.4–27.2 kg/mol) in good yield (71–78%). The secondary hydroxy groups in the polymer reacted easily with hexyl isocyanate, showing the potential of isopropyl aleuriteate as a comonomer for the synthesis of functional polyesters. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5968–5978, 2007     

Ionic absorption of polypropylene functionalized by surface grafting and reactions

Plasma-induced surface graft copolymerization of acrylic acid on polypropylene fibers and the subsequent reactions of the grafted carboxylic groups are reported. The extents of grafting was controlled by the plasma conditions. Reactions of the carboxylic acid with selected amines resulted in ion-exchanging and chelating functionalities. In general, ion adsorption is enhanced by higher levels of grafting and by raising temperature during adsorption. The adsorption level and preferences among ions of these functionalized fibers depend on the structure of the functional groups, i.e., the structure of the spacer and terminal groups. The carboxylic acid groups of the PP-g-AA fibers which behave like weakly acidic ion-exchangers are attributed to the low metal ion adsorption and the lack of ion preference. The F1 fibers with flexible  CH₂CH₂ spacer and small terminal  OH in the functional group exhibits highest ion adsorption among all functionalized fibers studied here. With benzene spacers, metal adsorption can be enchanced by the electron-donating nature of the terminal group. With the same ester end group in the functional structure, F3 fibers which contain benzene ring spacers show higher ion adsorption than F4 and F5 which have CH₂ and NH spacers, respectively. The ion preference and adsorption ability of the functionalized fibers, i.e., equilibrium binding constants (K_b) and saturation constants (K_s) derived from adsorption isotherms, also depend on the functional group structures. K_b increases with increasing grafting yield, increasing the electron donor atom in either terminal bonds or spacer, and reducing the steric hindrance of spacer. The K_s values are affected by the accessibility of functional groups, the size of spacer, and the terminal group structure. © 1997 John Wiley & Sons, Inc.     

The role of the medium in electrochemical functionalization and dispersion of carbon nanotubes

An electrochemical method for dispersion of single-walled carbon nanotubes (SWNTs) is described. The technique is based on grafting of oxygen-containing functional groups to the nanotube surface during electrolysis in aqueous and nonaqueous potassium bromide solutions. A dependence of the degree of functionalization of nanotubes on the solvent was revealed experimentally. Nanotubes treated in DMSO have about 14 carbon atoms per oxygen atom from functional groups (cf. nearly four C atoms per oxygen atom in the nanotubes treated in aqueous solutions). The corresponding maximum specific capacities of the electrodes are nearly 10 and 60 F g⁻¹. The samples treated in solutions of KBr in DMSO have about 300 carbon atoms per bromine atom on the nanotube surface (cf. only 30 carbon atoms in the samples treated in aqueous solution). A mechanism of electrochemical modification of SWNTs is proposed. Its key step is production of atomic oxygen that oxidizes the nanotube surface with the formation of functional groups.     

Synthesis of novel functional poly[(R,S)-ß-hydroxybutyrate] containing phosphonoacetate end groups

Amorphous poly[(R,S)-ß-hydroxybutyrate], containing both phosphonoacetate and carboxylate functional end groups, was synthesized via anionic polymerization of racemic ß-butyro-lactone initiated by supramolecular complexes of potassium P,P-dimethylphosphonoacetate. The living homopolymers, with alkali metal counter ions complexed with a crown ether, were utilized for the synthesis of block copolymers via condensation reaction with alkylene dihalides. As a result of this approach, coupled block copolymers containing phosphonoacetate functional end groups were obtained.     

T-for-H exchange reaction between HTO vapor and two functional groups in an aromatic compound in a gas-solid system

The hydrogen-isotope exchange reaction (T-for-H exchange reaction) between HTO vapor and an aromatic compound having two different kinds of functional groups has been observed at several temperatures. The rate constant (k) for each functional group in the T-for-H exchange reaction was obtained by using both theA″-McKay plot method and the data observed. Comparing thesek with each other has led to the following four conclusions in the T-for-H exchange reaction. (1) The reactivity of both the COOH and OH groups increases with a rise in temperature. (2) As to the degree of the effect of the COOH group on the reactivity of monosubstituted phenols, the degree inp-hydroxybenzoic acid is greater than that inm-hydroxybenzoic acid. (3) The HAMMETT rule is useful for estimating the reactivity of a certain aromatic compound. (4) TheA″-McKay plot method is also useful not only investigating the reactivity of the compounds having one kind of functional group, but also doing the reactivity of the compounds having two different kinds of functional groups.     

Chemoselective Synthesis of Z‐Olefins through Rh‐Catalyzed Formate‐Mediated 1,6‐Reduction

Z‐olefins are important functional units in synthetic chemistry; their preparation has thus received considerable attention. Many prevailing methods for cis‐olefination are complicated by the presence of multiple unsaturated units or electrophilic functional groups. In this study, Z‐olefins are delivered through selective reduction of activated dienes using formic acid. The reaction proceeds with high regio‐ and stereoselectivity (typically >90:10 and >95:5, respectively) and preserves other alkenyl, alkynyl, protic, and electrophilic groups.     

Toward Creation of a Universal NMR Database for Stereochemical Assignment: The Case of 1,3,5‐Trisubstituted Acyclic Systems

Using the diastereoisomeric triols 1a – d (Fig. 1) and examples summarized in Fig. 2, the central C‐atom of acyclic 1,3,5‐triols is demonstrated to exhibit a distinctive chemical shift that is dependent on the 1,3‐ and 3,5‐relative configuration, but is independent of the functionalities present outside of this structural motif. These NMR characteristics are then used to predict the relative configuration of several natural products (Fig. 7). In addition, an example is given to show the possibility of assembling an NMR database for a larger array of functional groups from NMR databases of smaller arrays of functional groups.     

Synthesis and antibacterial activities of water‐soluble methacrylate polymers containing quaternary ammonium compounds

New water‐soluble methacrylate polymers with pendant quaternary ammonium (QA) groups were synthesized and used as antibacterial materials. The polymers with pendant QA groups were obtained by the reaction of the alkyl halide groups of a previously synthesized functional methacrylate homopolymer with various tertiary alkyl amines containing 12‐, 14‐, or 16‐carbon alkyl chains. The structures of the functional polymer and the polymers with QA groups were confirmed with Fourier transform infrared and ¹H and ¹³C NMR. The degree of conversion of alkyl halides to QA sites in each polymer was determined by ¹H NMR to be over 90% in all cases. The number‐average molecular weight and polydispersity of the functional polymer were determined by size exclusion chromatography to be 32,500 g/mol and 2.25, respectively. All polymers were thermally stable up to 180 °C according to thermogravimetric analysis. The antibacterial activities of the polymers with pendant QA groups against Staphylococcus aureus and Escherichia coli were determined with broth‐dilution and spread‐plate methods. All the polymers showed excellent antibacterial activities in the range of 32–256 μg/mL. The antibacterial activity against S. aureus increased with an increase in the alkyl chain length for the ammonium groups, whereas the antibacterial activity against E. coli decreased with increasing alkyl chain length. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5965–5973, 2006     

The effect of molecular structure upon the response of the flame ionization detector

Summary It is known that the response of the FID is proportional to the number of carbon atoms in hydrocarbon molecules. If there is a heteroatom in the molecule, the response of the FID decreases. It is possible to calculate the sensitivity to any organic molecule if the signal-decreasing effect of a heteroatom or functional group is known. The sensitivity of a detector to an organic molecule containing heteroatoms is referenced to normal hydrocarbons by means of the effective carbon-atom number (ECN). Several authors have dealt with the determination ofECN values of different molecules and the effective carbon-atom number increment (ECN _inc) values for different functional groups and heteroatoms. In our previous work [1]ECN _inc values of several components were studied for homologous series. In this study we have investigated the effects of molecule structure upon ECN values by comparing theECN _inc of functional groups which are attached to molecules of different structure.     

Synthesis and phase‐separation behavior of α,ω‐difunctionalized diblock copolymers

A series of diblock copolymers of n‐pentyl methacrylate and methyl methacrylate (PPMA/PMMA BCP) with one or two terminal functional groups was prepared by sequential anionic polymerization of PMA and MMA using an allyl‐functionalized initiator and/or and end‐capping with allyl bromide. Allyl functional groups were successfully converted into OH groups by hydroboration. The morphology in bulk was examined by temperature‐dependent small‐angle X‐ray measurements (T‐SAXS) and transmission electron microscopy (TEM) showing that functional groups induced a weak change in d‐spacings L₀ as well as in the thermal expansion behavior. T‐SAXS proved that the lamellar morphologies were stable over multiple heating/cooling cycles without order‐disorder transition (ODT) until 300 °C. While non‐functionalized BCP formed parallel lamellae morphologies, additional OH‐termination at the PMMA block forced in very thin films (ratio between film thickness and lamellar d‐spacing below 1) the generation of perpendicular lamellae morphology through the whole film thickness, as shown by Grazing‐incidence small‐angle X‐ray scattering experiments (GISAXS) measurements. Functionalized BCP were successfully used in thin films as templates for silica nanoparticles in an in‐situ sol–gel process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

The sol fraction and conversions in AaBb type polymerisation

The sol fraction for the post-gel regime in A_aB_b-type polymerisations is investigated in a way which allows to study the total, the sol, the gel, the tree-gel and the loop-gel fractional conversions. Associated with these conversions, corresponding gel points are discussed as the threshold of sol-gel transition. (A_aB_b is a monomer with a functional groups of type A and b functional groups of type B.)     

Distribution of functional groups grafted onto an ethylene-propylene copolymer

A theoretical model, based on the binomial (Bernoullian) distribution function, was employed for the prediction of functional group distribution in an ethylene-propylene copolymer randomly grafted by maleic anhydride. Using the experimentally determined graft level and molecular weight distribution function, the fraction of polymer molecules with given number of functional groups was calculated. The result was checked experimentally by a fluorescence method based on the excimer formation of pyrene fluorophores attached to the anhydride pendants. The time-resolved fluorescence from the pyrene-labeled copolymer yielded the fraction of polymer molecules with a single functional group. The fraction of singly labeled molecules was compared to the calculated functional group distribution and a reasonable agreement was found between the two. The distribution of grafted maleic anhydride was found to be apparently random among polymer molecules. The distribution of distances was calculated between randomly attached consecutive functional groups along the polymer backbone also. The result indicated that the distance distribution function (similar to a decaying exponential) is dominated by short distances. © 1996 John Wiley & Sons, Inc.     

Synthesis of a Pillar[5]arene with Both Hydroxyl and Methoxycarbonyl‐Methoxy Groups and Its Host‐Guest Complexation with a Bis(imidazolium) Salt

By the introduction of methoxycarbonyl‐methoxy groups and hydroxyl groups into a pillar structure, a pillararene entirely with two types of functional groups was successfully prepared, which can form a stable 1:1 complex with a bis(imidazolium) salt in CHCl₃/acetone solution (V:V=1:1).