Acidolytic polymerization of N-methyldodecanelactam

The polymerization rate of 1-methylazacyclotridecan-2-one (N-methyldodecanelactam) ( 1 ) initiated with dodecanoic acid ( 2 ) can be described within the whole range of conversions in terms of the simple relation In ([ 1 ]₀/[ 1 ]) = k[ 2 ]₀t, in spite of the complexity of the overall reaction scheme. The rate constants (k) determined for 240, 260, and 280°C are 0,32, 1,21, and 3,4 kg · mol^?1 h^?1, respectively, and the constants of the Arrhenius equation are A = 6,6 · 10¹³kg · mol^?1 h^?1, E = 140 kJ · mol^?1. The resulting poly(N-methyldodecaneamide) ( 3 ) is a semicrystalline polymer (m.p. 65°C), soluble in polar organic solvents. The following constants of the Mark-Houwink equation were determined for solutions of this polyamide: for 5000 < M?_w < 150 000 g · mol^?1 at 25°C in THF (2-propanol), K = 0,124 (0,161) cm³ · g^?1, a = 0,59 (0,56); for 5 000 < M?_w < 80 000 g · mol^?1 at ?-temperature = 30,5°C in 1,4-dioxane, K = 0,215 cm³ · g^?1, a = 0,50. Analyses of molar masses, both theoretical and experimental (light-scattering, GPC, osmometry, end groups), indicate that at the polymerization temperature of 280°C side reactions already take place, reflected in random cleavage and in branching of chains.     

Kinetics of the anionic polymerization of ϵ-caprolactone with K+ · (dibenzo-18-crown-6 ether) counterion. Propagation via macroions and macroion pairs

Following our earlier work on the polymerization of lactones involving crowned cations, kinetics of the anionic polymerization of ?-caprolactone (?CL) with K⁺ · (dibenzo-18-crown-6 ether) (K⁺DB18C6) counterion was studied calorimetrically in THF solution in the temperature range from 0 to 20°C. Dissociation constants of CH₃(CH₂)₅O^?K⁺DB18C6, modelling the active centers, were determined conductometrically: K_D (20°C) = 7,7 · 10^?5 mol · dm^?3, ΔH = 9,3 ± 0,2 kJ · mol^?1, ΔS = ?47 ± 2J · mol^?1 · K^?1. From kinetic measurements and from measurements of the dissociation constant of CH₃(CH₂)₅O^? K⁺DB18C6, rate constants of propagation via macroions and via macroion pairs were determined. Activation parameters for propagation via these species are equal to: ΔH = 39,2 ± 0,2 kJ · mol^?1, ΔS = ?63 ± 1 J · mol^?1 · K^?1, ΔH = 13,7 ± 0,1 kJ · mol^?1, ΔS = ?185 ± 2 J · mol^?1 · K^?1. At 20°C, k = 3,50 · 10² dm³ · mol^?1 · s^?1 and k = 5,2 dm³ · mol^?1 · s^?1. Due to the large difference of ΔH^≠ for propagation via macroions and macroion pairs (vide supra), the isokinetic point (k = k) would appear at ?65°C.     

Polymerization of lactams, 54. Anionic polymerization of 2-pyrrolidone accelerated with CO2, part 3

Intrinsic viscosities in m-cresol and weight average molecular weights, M?_w, were measured for samples of high molecular weight poly(2-pyrrolidone) (poly ( 1 )) prepared by anionic polymerization of 2-pyrrolidone ( 1 ) accelerated with CO₂. It was proved that the earlier found relationship [η] = 4 · 10^?2 · M^0,77 (in cm³ · g^?1) holds for M?M_w up to 8 · 10⁵ g. mol^?1. The probable reason for the formation of poly ( 1 ) with an exceptionally high molecular weight is discussed.     

Viscosity and intrinsic viscosity/temperature relationships for dilute solutions of poly(2-biphenylyl methacrylate) and poly(4-biphenylyl methacrylate)

The actual viscosity η and the intrinsic viscosity [η] of six fractions of poly(2-biphenylyl methacrylate) {poly[1-(2-biphenylyloxycarbonyl)-1-methylethylene], (POB); weight average molecular weight M?_w: 4,0 · 10⁴ to 1,42 · 10⁶, polydispersity ratio M?_w/M?_n ≈ 1,4} and of three fractions of poly(4-biphenylyl methacrylate) {poly[1-(4-biphenylyloxycarbonyl)-1-methyl-ethylene], (PPB); M?_w : 8,1 · 10⁴ to 5,3 · 10⁵, M?_w/M?_n ～ 1,4} in benzene have been determined at different temperatures between 20 and 60°C. Values of the apparent activation energy of the viscous flow Q and the pre-exponential term A in the expression η = A · exp[Q/(RT)] have been obtained. Q varies with M?_w and concentration c according to Moore's equation: Q = Q₀ + K_e · M · c, where Q₀ refers to the solvent and K_e depends on polymer and solvent. The numerical value of K_e for POB and PPB is 1,6 · 10^?4 (6,7 · 10^?4) and -8,1 · 10^?4 cal · dl · g^?1 (-3,4 · 10^?3 J · dl · g^?1), resp. From all polymethacrylates studied POB is the only polymer with a positive K_e value. The positive value of K_e for POB may possibly be related to the more extended form of POB in benzene and also may be connected, at least partly, with its low flexibility. The temperature coefficient of the unperturbed dimensions dln〈r₀²〉/dT for POB estimated from the viscosity data using the Burchard-Stockmayer-Fixman relation, is 0,14 · 10^?3, much lower than for PPB (2,3 · 10^?3 between 22 and 40°C and 1,2 · 10^?3 between 40 and 60°C). The positive values of dln〈r₀²〉/dT indicate that extended conformations of these polymers in benzene must be associated with higher energies.     

Molecular size and configuration of poly(3-vinylpyrene)

Solution properties of poly(3-vinylpyrene) (PVπ) have been studied to determine the degree of hindrance to the flexibility of the vinyl chain by the pyrene pendant group. Fractionation of this polymer prepared by anionic polymerization, yielded nine narrow distribution fractions in the M_w range of 35 000–490 000 and the fractions were characterized by osmometry, light-scattering and viscometry. Intrinsic viscosities of the fractions were obtained in chloroform and tetrahydrofuran at 25°C and in o-dichlorobenzene at different temperatures from 25–80°C. From the KUHN-MARK-HOUWINK relationship, [η] = KM^a, K and a values were determined and the exponent varied in the order, chloroform (a = 0.500) < tetrahydrofuran (a = 0.547) < o-dichlorobenzene (a = 0.655) suggesting that chloroform at 25°C is a theta solvent for PVπ. Cloud point titration indicated that a mixture of THF/methanol in the ratio of 92:8 (V/V) is also a theta solvent for PVπ at 25°C. A K_Θ value of 5.2·10^?4 determined for PVπ at 25°C gave a value for the unperturbed dimension (R /M)^1/2 of 5.77·10^?9 cm. The conformational parameter, σ was computed as 2.84 for PVπ which suggests that the hindrance to rotation of the vinyl chain by the pyrene group is approximately the same as in the case of carbazole in poly(n-vinylcarbazole). Values of [η] in o-dichlorobenzene decreased with the increase of temperature yielding an average negative d log [η]/dT value of 1.1·10^?3. The expansion factor decreased in all cases with the rise of temperature. A decrease of unperturbed dimension with the increase of temperature was reflected in the d log K_Θ/dT value of ?2.0·10^?3 from which (R /M)^1/2 at 80°C was computed as 5.35·10^?9 cm.     

Concurrent Initiation by Air in the Atom Transfer Radical Polymerization of Methyl Methacrylate

The effect of air in atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was studied. Air initiated polymerization was clearly noticed by the appearance of a low molecular weight peak in the synthesis of high molecular weight poly(isobutylene)‐graft‐poly(methyl methacrylate) (M _n = 5.0 × 10⁵ g/mol). The concentration of chains initiated by oxygen (air) was ≈8 × 10^?4 mol/L, determined using the Gladstone‐Dale relationship. The tentatively proposed mechanism for air initiated polymerization was supported by kinetic studies. Similar to typical ATRP systems, the rate of air initiated polymerization increased with temperature, [MMA], amount of air, and activity of the catalyst complex. Polymers with lower polydispersities (M _w/M _n = 1.13) were obtained in the presence of Cu(II) as compared to Cu(I) catalyst complex system.

Kinetic plots for the air initiated bulk polymerization of MMA at (?) 20 °C, (?) 50 °C, and (?) 90 °C.     

Anionic polymerization of butyl cyanoacrylate by tetrabutylammonium salts, 2. Propagation rate constants

Anionic polymerizations of butyl cyanoacrylate were initiated in tetrahydrofuran (plus a few experiments in 1,2-dimethoxyethane) by the salts tetrabutylammonium hydroxide, bromide, acetate and three substituted acetates. The hydroxide gives near-ideal ‘living polymerization’ kinetics, with k_p close to 10⁶l·mol^?1. s^?1 at 20°C. The kinetics of the reactions initiated by the acetates and bromide are analysed by the slow-initiation-no-termination theory, using values of the initiation rate constants evaluated in Part 1. The k_p values derived are in the same range as those from the OH-initiated reactions and those of the zwitterionic polymerizations initiated with covalent bases, i.e., tertiary phosphines and amines. A ca. 4-fold variation of k_p with concentration of active species is given a speculative analysis in terms of dissociation from paired to free ions, yielding tentative estimates for k ≈ 10⁵ and k ≈ 10⁷l·mol^?1·s^?1 in THF at 20°C. Molecular weights were all high M _n ≈ 10⁶, with M _w/M _n ≈ 2.     

The initiation of polymerization of unsaturated tertiary amines with carboxylic acids

The polymerization rate (R_p) of N-methyl-N-phenyl-2-aminoethyl methacrylate (MPAEMA) initiated with 2,2' -azodiisobutyronitrile (AIBN) at 50°C increased considerably after the addition of CCI₃COOH, and distinctly after the addition of CH₃COOH. R_p in a benzene solution of 2 mol. dm^?3 MPAEMA and 5 · 10^?2 mol. dm^?3 CCl₃COOH (without AIBN) was 13% · h^?1. [η] of the obtained polymer corresponded to 64 cm³ · g^?1. The polymerization order of MPAEMA initiated with CCl₃COOH is 0,93 with respect to monomer and 0,51 with respect to CCl₃COOH. The overall activation energy of polymerization of MPAEMA calculated from the temperature dependence of R_p between 20 and 50°C is 43 ± 1,2 kJ · mol^?1. In a benzene solution of 2 mol.dm^?3 MPAEMA, 5 · 10^?2 mol · dm^?3CCl₃COOH and 5 · 10^?3 mol · dm^?3 1,4-benzoquinone at 50°C the polymerization does not proceed for 6 h. In a benzene solution of 2 mol · dm^?3 4-dimethylaminostyrene (4-DMAS) and 2 mol · dm^?3 CH₃COOH (without AIBN), 40% of monomer polymerized within one hour. [η] of the polymer was 4 cm³ · g^?1. The overall activation energy of polymerization of 4-DMAS in the presence of CH₃COOH is ca · 54 kJ · mol^?1. The addition of 5 · 10^?3 1,4-benzoquinone slows down the polymerization rate only slightly. The effect of acids on the elementary polymerization reactions is characterized.     

Study on the molecular weight dependence of dilute solution properties of narrowly distributed polystyrene in toluene and in the unperturbed state

Intrinsic viscosities [η], second and third virial coefficients A₂ and A₃, respectively, and mean square radius of gyration 〈R_G²〉 of a polymer homologous series of narrow-molecular-weight-distribution polystyrene samples in a molecular weight range of 2000 up to 24 · 10⁶ were determined in toluene at 25°C by light scattering and viscometry measurements. The results are (3 · 10⁴ < M_w < 24 · 10⁶, M_w/M_n ≤ 1,3): These results were obtained by consideration of the limit of the dilute solution regime, the determination of zero-shear rate intrinsic viscosities, and the molecular weight dependence of the refractive index increment dn/dc. It was found that dn/dc increases slightly up to M_w = 1,8 · 10⁶. A comparison of the [η]?M_w-relationship with literature data is given. In addition the unperturbed (theta) dimension parameters K₀, 〈h²〉₀/M, the characteristic ratio C_∞, the steric factor σ, and the thermodynamic interaction parameter B were calculated from the modified Burchard-Stockmayer-Fixman procedure using polymolecularity correction and the results compared with experimental data from the literature.     

Laser light scattering studies of soluble high performance fluorine-containing polyimides, 1. Polyimide synthesized from 2,2′-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride and 2,2′-(trifluoromethyl)-4,4′-biphenyldiamine

Five fractions of a polyimide synthesized from 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′-(trifluoromethyl)-4,4′-biphenyldiamine (PFMB) (6FDA/PFMB) in tetrahydrofuran (THF) at 30°C were investigated by a combination of static and dynamic laser light scattering (LLS). The relations of 〈R_h〉 (nm) = 2.38 x 10^?2 M _w^0.560 and A₂ (mol · cm^?3 · g^?2) = 2.1 × 10^?1 M _w^?0.43 were established, where M _w, 〈R_h〉 and A₂ are weight-average molecular weight, average hydrodynamic radius and second virial coefficient, respectively. A combination of M _w and the translational diffusion coefficient distribution G(D) leads to a relation of D(cm²/s) = 2.41 × 10^?4 M ^0.564. With this relation, we successfully convert each G(D) into a corresponding molecular weight distribution (MWD). On the basis of the Benoit-Doty theory, we found that the persistence length and the Flory characteristic ratio C_∞ of the 6FDA-PFMB chain are ～3.3 nm and ～40, respectively, indicating that the 6FDA-PFMB chain is more extended than typical random-coil chains. On the other hand, the ratio of the radius of gyration to the hydrodynamic radius, i.e., 〈R_g〉/〈R_h〉 ～ 1.8, together with the values of the exponents (～0.56) indicate that the 6FDA-PFMB chain has a coil chain conformation. Therefore, the 6FDA-PFMB chain has an extended coil conformation in THF at 30°C.     

Über die polymerisation von 1-chlor-2,3-epoxypropan

The kinetics and the thermodynamic features of the polymerization of 1-chloro-1,3-epoxypropane with the complex \documentclass{article}\pagestyle{empty}\begin{document}${\rm Cl}_{\rm 5} \mathop {{\rm Sb}}\limits^ \ominus \cdots \mathop {\rm S}\limits^ \oplus {\rm O}_2$\end{document} were studied. It was found that the process proceeds with a negative temperature coefficient, E_a=?51,29 kJ/mol ( ? 12,25 kcal/mol), ΔH_p=?18,8 kJ/mol (?4,5kcal/mol), ΔS_p=?74,5 J mol^?1 K^?1 (?17,8 cal mol^?1 K^?1), and with the ceiling temperature of 52,6°C. The molecular masses of the polymers were determined and a possible mechanism of the polymerization process was suggested.     

Kinetics and molecular weight evolution during controlled radical polymerization

Automatic, continuous online monitoring of polymerization reactions (ACOMP) was applied to the controlled radical polymerization (CRP) of butyl acrylate (BA) using N‐tert‐butyl‐1‐diethylphosphono‐2,2‐dimethylpropyl nitroxide (SG1), to determine monomer conversion, evolution of molecular weight, reduced viscosity, and rate constants. The conversion is roughly first order, but depends only on the initial ratio of free SG1 to initiator; i.e., it is zeroeth order in initiator concentration. While it was found that the weight‐average molecular weight M _w, and viscosity‐average mass increase in approximately linear fashion with conversion, their values are finite at zero conversion. Although ACOMP involves no chromatographic separation columns, a useful measure of polydispersity evolution was found from combining M _w and viscosity‐based masses. CRP is contrasted with monitoring results for conventional free‐radical polymerization. Distinct light‐scattering signatures are expected, and found experimentally, for the two cases. The CRP kinetic findings allowed the determination of the equilibrium constant between active and dormant species at 120 °C (K_eq = 1.53 × 10⁻¹⁰ M ), as well as the corresponding kinetic constant of deactivation (k_deact = 2.8 × 10⁺⁷ L · mol⁻¹ · s⁻¹) and activation (k_act = 4.2 × 10⁻³ s⁻¹). Cross‐checks on the monitoring results were made with conventional Gel Permeation Chromatography (GPC), and kinetic behavior was also analyzed in the light of numerical integration software.

Raw data for PBA CRP reaction #6 in Table 1 vs. detector time, which lags the reaction time by 800 s. Shown are viscosity, RI, UV and 90 degree light‐scattering signals, together with the time at which stabilization, monomer flow, and polymerization began. The temperature curve is offset to the left 800 s with respect to the detector signals.     

Transition‐Metal‐Catalyzed Chain‐Growth Polymerization of 1,4‐Diethynylbenzene into Microporous Crosslinked Poly(phenylacetylene)s: the Effect of Reaction Conditions

Chain‐growth polymerization of 1,4‐diethynylbenzene into conjugated crosslinked polyacetylene‐type poly(1,4‐diethynylbenzene)s (PDEBs) is reported. While metathesis catalysts (WCl₆/Ph₄Sn, MoCl₅/Ph₄Sn, Mo Schrock carbene) fail in this polymerization, insertion Rh catalysts ([Rh(nbd)acac], [Rh(nbd)Cl]₂) provide microporous PDEBs in high yields. The Brunauer–Emmett–Teller (BET) surface, S_BET, of PDEBs prepared with [Rh(nbd)acac] increases, in dependence on the polymerization solvent, in the order: THF << pentane < benzene < methanol < CH₂Cl₂. S_BET further increases with both increasing monomer concentration and increasing polymerization temperature and reaction time, reaching a highest value of 1469 m² g^?1. In addition to micropores, PDEBs contain mesopores. The mesopore volume and average mesopore diameter increase with the time and the temperature of the polymerization up to 2.52 cm³ g^?1 and 22 nm (72 h, 75 °C). The post‐polymerization thermal treatment of PDEB (280 °C) results in formation of new crosslinks and modification of PDEB texture and sorption behavior manifested mainly by enhancement of H₂ adsorption capacity up to 4.55 mmol g^?1 (77 K, 750 Torr).

     

Hyperbranched Polyalkoxysiloxanes via AB3‐Type Monomers

We have synthesized polyethoxysiloxanes starting from the AB₃‐type monomers triethoxysilanol and acetoxytriethoxysilane. The polymers are liquid and soluble in organic solvents. ²⁹Si NMR spectroscopy and MALDI‐ToF mass spectrometry analyses show that the polymers have a hyperbranched structure with additional internal cyclization. ²⁹Si NMR spectroscopy indicates that the polymer synthesized from acetoxytriethoxysilane is less branched than the polymer synthesized from triethoxysilanol. Analysis of the molar mass and mass distribution of the polymers via size exclusion chromatography (calibrated via MALDI‐ToF MS and viscosimetry) yields a molar mass of M _n ≈ 2 kg · mol^?1 and M _w ≈ 8 kg · mol^?1 for polymers synthesized from triethoxysilanol. The molar mass of the polymers synthesized from acetoxytriethoxysilane can be controlled by variation of the polymerization time in the range of M _n ≈ 1.8–12 kg · mol^?1 and M _w ≈ 2.1–2 200 kg · mol^?1.

Photograph of a vial containing polyethoxysiloxane obtained from triethoxysilanol and a schematic drawing of the proposed molecular structure of the polymer.     

Synthesis of high-molecular-weight poly(L-lactide) initiated with tin 2-ethylhexanoate

The bulk polymerization of L ,L -dilactide was studied as a function of polymerization temperature (T_p), time and concentration of catalyst (tin 2-ethylhexanoate). Poly(L -lactide) (PLLA), with the highest value of intrinsic viscosity ([η] = 13 dl · g^?1; M?_v ≈ 1 · 10⁶) and heat of fusion (ΔH_m = 64,7 J · g^?1), was synthesized at a low catalyst concentration (0,015 wt.-%) and at the lowest T_p studied (100°C), just above the melting point of L ,L -dilactide (98°C). The ceiling temperature of PLLA was found to be 275°C, as deduced from an M?_{v max.} ? T_p curve. The M?_w/M?_n ratios of as-polymerized PLLA samples ranged from 2 to 3. Fractions of PLLA with M?_{v max.} were already present at 50% conversion. The experimental results support a proposed nonionic insertion polymerization mechanism. Polymerization at 100–140°C resulted in early crystallization of PLLA leading to a rather untangled polymer and microporous (pores up to 100 nm) sample texture.     

Free-radical polymerization of methyl methacrylate initiated by N,N-dimethylaniline

N,N-Dimethylaniline (DMA) does initiate the free-radical polymerization of methyl methacrylate (MMA), methyl acrylate, and methyl vinyl ketone. The overall rates of polymerization of MMA were obtained at 40, 50, and 60°C. From the results of a detailed kinetic investigation, the activation enthalpy and activation entropy of polymerization were calculated as 63,2 kJ mol^?1 and ?153 J mol^?1 K^?1 at 60°C. Rate equation was also obtained as R_p = k[DMA]^1/2[MMA]^3/2 and the polymerization was inhibited by benzoquinone. Though styrene alone was not polymerized by DMA, the copolymerization of MMA with styrene by DMA (reactivity ratios: r_MMA=0,45 and r_St=0,50) followed a typical free-radical mechanism. An electron-transfer complex between DMA and MMA is proposed as the initiation species.     

Free radical polymerization in the presence of non-solvents, 1. Styrene

During styrene (STY) polymerization, initiated by radicals formed by thermal or photochemical decomposition of 2,2′-azoisobutyronitrile (AIBN) the overall polymerization rate constant K defined by relation K = R^p/([AIBN]^0,5 [STY] η) and the ratio k_p/(2k_t0) increase with decreasing styrene concentration by hexane or benzene (R_p is the polymerization rate and η_MIX the viscosity of the reaction system). In the thermally initiated polymerization K = k_p (2f k_d/(2k_t0))^0,5 and in the photochemically initiated polymerization K = k_p (2,303 ? I₀? d/(2k_t0))^0,5 where k_d, k_p, and k_t0 are respectively, the rate constants of AIBN decomposition, of propagation, and of termination (for a system of the viscosity 1 mPa·s) reactions, ? is the quantum yield of radicals entering into reaction with the monomer, I₀ the intensity of the incident light, ? the molar absorption coefficient of AIBN, and d the path length of the light. The increase of K and of k_p/(2k_t0) with decreasing monomer concentration is more marked for the system styrene/hexane than for styrene/benzene and this increase is greater at 30°C than at 60°C. For Θ-systems formed by binary mixtures like styrene/hexane, styrene/decane and styrene/C₁ – C₄ alcohols the values of k_p and k_t0 at 30°C range between 57 and 91 dm³·mol^?1·s^?1 and (0,9 to 2,2)·10⁷ dm³·mPa·mol^?1, i.e. they are in principle identical with the tabulated values of these rate constants for styrene bulk polymerization.     

EPR Investigations into the Kinetics of Trithiocarbonate‐Mediated RAFT‐Polymerization of Butyl Acrylate

Electron paramagnetic resonance (EPR) spectroscopy is used for measuring rate coefficients of addition, k_ad, and fragmentation, k_β, together with the associated equilibrium constants, K_eq, for butyl acrylate polymerizations mediated by S‐ethyl propan‐2‐ylonate‐S’‐propyl trithiocarbonate (EPPT) and by S‐S’‐bis(methyl‐2‐propionate) trithiocarbonate (BMPT). Experiments at ?40 °C yield k_ad = (3.4 ± 0.3) × 10⁶ L mol^?1 s^?1, k_β = (1.4 ± 0.4) × 10² s^?1, and K_eq = (2.6 ± 0.8) × 10⁴ L mol^?1 for EPPT and k_ad = (4.1 ± 0.9) × 10⁶ L mol^?1 s^?1, k_β = (4.5 ± 0.5) × 10¹ s^?1, and K_eq = (8 ± 4) × 10⁴ L mol^?1 for BMPT. The K_eq values are in satisfactory agreement with data from ab initio calculations.

     

Anionic polymerization of 2-Oxo-1,3,2λ5-dioxaphosphorinane. Thermodynamics

Thermodynamics of the polymerization of 2-oxo-1,3,2λ⁵-dioxaphosphorinane in bulk initiated by sodium metal is described. Enthalpy (ΔH_p = 6,28 ± 0,84 kJ · mol^?1) and entropy (ΔS = 19,25 ± 2,51 J · mol^?1 · K^?1) of polymerization were evaluated from the temperature dependence of the equilibrium nomomer concentration determined directly by ³¹P{¹H} NMR. The results are compared with those obtained previously for the polymerization of other 2-alkoxy-2-oxo-1,3,2λ⁵-dioxaphosphorinanes.