Alkanediols Research Articles

Safety Assessment of Alkane Diols as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 10 alkane diol ingredients as used in cosmetics. The alkane diols are structurally related to each other as small diols, and most are reported to function in cosmetics as solvents. The Panel reviewed the relevant data for these ingredients, and concluded that seven alkane diols are safe in cosmetics in the present practices of use and concentration described in this safety assessment, but that the available data are insufficient to make a determination of safety for three ingredients, namely 1,4-Butanediol, 2,3-Butanediol, and Octanediol.

Synthesis of triphyrin(2.1.1)-triphyrin(2.1.1) homo dimers and bis-Re(I) triphyrin dimer complex.

First examples of covalently linked triphyrin(2.1.1)-triphyrin(2.1.1) homo dimers connected via flexible alkoxy linkers at β-pyrrole positions were synthesized in 28-30% yields by reacting 2-bromo triphyrin(2.1.1) with three different alkane diols such as 1,2-ethanediol, 1,4-butanediol and 1,6-hexanediol in toluene under Pd2(dba)3/DPEphos catalyzed conditions by refluxing for 12-20 h. One of the free base triphyrin-triphyrin homo dimers was metallated by treating the homo dimer with Re(CO)5Cl in toluene under reflux and afforded bis-Re(I) homo dimer complex in 53% yield. Three free base homo dimers and one bis-Re(I) homo dimer complex were thoroughly characterized and studied using HR-MS, 1D and 2D NMR, absorption spectroscopy, cyclic voltammetry and DFT calculations. Our attempts to obtain the X-ray structure of homo dimers were not successful. However, DFT studies revealed that homo dimers prefer to exist in anti-conformation rather than syn-conformation and both triphyrin macrocycles in homo dimers were similar in terms of the deviation of pyrrole rings from the mean plane defined by the four meso carbons of the respective triphyrin unit. Absorption spectra of homo dimers showed similar absorption features such as in triphyrin(2.1.1) with slight changes in their absorption peak maxima. Electrochemical studies revealed that the homo dimers were electron rich, whereas the bis-Re(I) complex was electron deficient in nature.

Biodegradable and pH-responsive piperazine-based aliphatic polyesters with tunable hydrophilicity

In this article, we report on a new class of biodegradable piperazine-based aliphatic pH-responsive polyesters with tunable hydrophilicity. The aliphatic polyesters PC1-PC4 with high thermal stability up to 340 °C were synthesized by polycondensation of dimethyl 2,2′-(piperazin-1,4-diyl)diacetate with a series of alkane diols (C4 to C10). The resulting polyesters are found to be highly crystalline with ∼47–55% crystallinity as estimated from XRD and moderately hydrophilic as the water contact angle was found to be in the range of 63°–72°. An N-alkylation or protonation approach was used to tune their crystallinity and hydrophilicity so as to enhance biodegradability. Upon quaternization with methyl iodide, a significant effect on functional and structural properties was observed with reduced crystallinity and enhanced hydrophilicity, as the contact angle decreased down to 24° upon methylation. The pH-responsive nature of the material was evaluated with zeta potential measurements, and the surface charge increased up to +41.4 mV with a more positive charge on the polymer backbone at pH 2 for polyester PC2. Further, microbial and hydrolytic degradation studies showed that the quaternized polyesters PC6 and PC9 exhibit faster degradation when compared to their parent polymer PC2, demonstrating their significance as a new class of biodegradable polyesters.

Effect of Linker Length and Temperature on the Thermal Conductivity of Ethylene Dynamic Networks.

Dynamic covalent networks are a class of polymers containing exchangeable bonds. The influence of the thermodynamics and kinetics of dynamic bond exchange on the thermal conductivity and mechanical properties of dynamic networks is important for understanding how they differ from thermoplastics and thermosets. In this work, a series of ethylene dynamic networks are synthesized from benzene diboronic acid and alkane diols with different precise ethylene linker lengths. The thermal conductivity of these ethylene dynamic networks at 40 °C decreases from 0.19 to 0.095 W/(m K) when the ethylene linker length increases from 4 to 12 carbons. The thermal conductivity also has a strong temperature dependence, decreasing by a factor of 3 over the temperature range from -80 °C to 100 °C. The minimum thermal conductivity model predicts these trends of the thermal conductivity with variations in ethylene linker length and temperature.

Starch/Alkane Diol Materials: Unexpected Ultraporous Surfaces, Near-Isoporous Cores, and Films Moving on Water.

The aim of this study was to find alternative starch plasticizers to glycerol that yielded a less tacky material in high-moisture conditions without leading to starch crystallization. A range of glycerol films containing different potential plasticizers (linear alkane diols) were therefore produced, and it was shown that 1,3-propanediol, in combination with glycerol, was a possible solution to the problem. Several additional interesting features of the starch films were however also revealed. The larger diols, instead of showing plasticizing features, yielded a variety of unexpected structures and film properties. Films with 1,6-hexanediol and 1,7-heptanediol showed an ultraporous film surface and near-isoporous core. The most striking feature was that starch films with these two diols moved/rotated over the surface when placed on water, with no other stimulus than the interaction with water. Films with 1,8-octanediol and 1,10-decanediol did not show these features, but there was clear evidence of a structure with phase-separated crystallized diol in a starch matrix, as observed in high-resolution scanning electron microscopy (SEM) images.

Synthesis of biphenyl polyesters derived from divanillic acid, and their thermal and mechanical properties

Four different symmetric dialkoxydivanillic acid monomers with different side-chain lengths, namely methoxy-, ethoxy-, propoxy-, and butoxy-divanillic acid monomers (MeDVA, EtDVA, PrDVA, and BuDVA) (side-chain carbon number; m = 1, 2, 3, and 4), were synthesized. Polymerizations of the DVA-based monomers with alkane diols with different alkyl carbon number (m’ = 4 and 6) were conducted with titanium tetraisopropoxide as a catalyst via bulk transesterification, and a series of DVA-based polyesters P(R′-RDVA) (m = 1, 2, 3, and 4, m’ = 4 and 6) were obtained. The weight-average molecular weight (Mw) of the polyesters reached 6.24 × 104 for poly(hexylene dibutoxydivanillate) [P(He-BuDVA)]. The obtained polyesters had high thermal stabilities with thermal degradation temperatures at 10% weight loss of ca. 380 °C on average. Differential scanning calorimetry showed that these DVA-based polyesters had no melting temperature and were amorphous. Their glass-transition temperatures varied from 19 to 89 °C, depending on the side-chain and diol-chain lengths. Cast films and melt-pressed films of the polyesters were obtained, and their mechanical properties were investigated by tensile testing. The P(Bu-BuDVA) and P(He-PrDVA) samples had maximum strengths of 15.8 and 7.5 MPa, respectively. The P(He-BuDVA) sample was highly stretchable. The stretched specimen of P(He-BuDVA) film from the tensile catch, it shrunk and recovered ca. 400% elongation from ca. 1600% stretching.

화장품에서 1,3-부틸렌 글라이콜 및 알칸디올계 조성에 따른 방부력에 관한 연구

최근 화장품에서 방부제로 사용되는 파라벤류는 인체 안전성에 대한 문제가 이슈화되고 있다. 따라서 본 연구에서는 파라벤류를 대체할 수 있는 방부시스템으로 1,3-butylene glycol, 1,2-hexanediol 및 1,2-pentanediol의 함량에 따른 방부력 효능을 평가하고자 하였다. 화장품 크림에 1,3-butylene glycol을 5 - 25% 사이의 농도로 첨가하였다. 1,3-Butylene glycol의 방부력은 Personal Care Products Council (CTFA)의 M-3 시험법으로 측정하였다. 알칸 디올계인 1,2-hexanediol 및 1,2-pentanediol도 유사한 방법으로 평가하였다. 1,3-Butylene glycol의 함량에 따른 방부력 평가 결과, 25%를 첨가한 크림 처방에서 모든 시험 균주에 대하여 방부력을 나타내었으며, phenoxyethanol 0.3%와 ethylhexylglycerin 0.1%가 혼합된 처방에서 방부력을 나타내었다. 방부제인 phenoxyethanol의 0.3% 함량을 대체할 수 있는 대체 방부제로 alkane diol계인 1,2-hexanediol과 1,2-pentanediol을 선정하여 방부력 평가를 진행하였다. 1,2-Hexanediol과 1,2-pentanediol의 조성에 따른 방부력 평가 결과, 1,2-hexanediol 1%와 1,2-pentanediol 1%의 혼합 처방에서 방부력을 나타내었다. 결과적으로 본 연구에서는 25%의 1,3-butylene glycol과 0.1%의 ethylhexylglycerin, 1%의 1,2-hexanediol 및 1%의 1,2-pentanediol의 처방은 가장 우수한 방부력을 나타냄을 입증하였다. 따라서 이러한 처방은 화장품에서 사용되어 안전성의 이슈가 되어온 파라벤류 방부제를 대체할 수 있는 가능성이 있음을 시사한다.

Hydrogen bond network-stabilisation of blue phases by addition of a chiral N-(10-hydroxydecyl)succinimide derivative and alkane diols

ABSTRACTBlue phases (BPs) obtained by doping a commercially available liquid crystalline compound (4-butyl-N-(4-ethoxybenzylidene)aniline (EBBA)) with (2R,3R)-2,3-bis(4-octyloxyphenylbenzoyloxy)-N-(hydroxydecyl)succinimide (1) were highly stabilised by the addition of a small amount of alkane diols. Especially, addition of only 0.5 mol% of octane-1,8-diol increased the BP–Iso transition temperature by 10 K and widened the BP temperature range up to 35 K. A model stabilisation mechanism based on the construction of a hydrogen bond network in each disclination zone in BPs was proposed.

Excess Gibbs Energy and Local Compositions in the Mixtures C2, C3 Alkane Diols and Triols with Water at Various Pressures

In this work the excess molar Gibbs energy of binary mixtures of water with ethylene glycol, 1,2-propanediol, 1,3-propanediol or glycerol was calculated at 298.15 K and pressures from 0.1 to 100 MPa. Thermodynamic data were used to calculate the Kirkwood–Buff integrals and the parameters of local composition (∆n ij ). The excess Gibbs energies and parameters of local compositions for aqueous mixtures of the alcohols with different number of hydroxyl groups and internal structures are compared. Similar character of intermolecular interactions has been established for all mixtures studied. It was discovered that external pressure causes an increase of local nonhomogeneity for all systems. The pressure influence was more pronounced for the aqueous mixtures of propanediols.

Association of symmetrical alkane diols with pyridine: DFT/GIAO calculation of 1H NMR chemical shifts

Proton nuclear magnetic resonance (NMR) shifts of the free diol and of its 1 : 1 and 1 : 2 hydrogen-bonded complexes with pyridine have been computed for five symmetrical alkane diols on the basis of density functional theory, by applying the gauge-including atomic orbital method to geometry-optimized conformers. For certain conformers, intramolecular OH···OH interactions, evidenced by high NMR OH proton shifts, are further enhanced on going from the free diol to the corresponding 1 : 1 diol/pyridine complex. This is confirmed by atoms-in-molecules and non-covalent interaction plots. The computed OH and CH proton shifts for the diol and the two complexes correlate well with values obtained by analysing data from the NMR titration of the diols in benzene against pyridine. Shift values for the diols in neat pyridine are calculated by weighting the shifts of the various protons in the three forms (free diol, 1 : 1 and 1 : 2 diol/pyridine complexes) according to the experimentally determined association constants. The results are in good agreement with those observed, and after empirical scaling, the root mean square difference is 0.18 ppm. Copyright © 2016 John Wiley & Sons, Ltd.

Atom-Economic, Metal- and Halogen-Free Synthesis of Podands: α,ω-Diphosphines and Their Chalcogenides Separated by Alkane Diol Spacers

Atom-Economic, Metal- and Halogen-Free Synthesis of Podands: α,ω-Diphosphines and Their Chalcogenides Separated by Alkane Diol Spacers

Synthesis, characterization and biodegradation studies of chain-coupled polyesters based on tartaric acid

A series of chain-coupled polyesters based on tartaric acid was synthesized and characterized following a two-step procedure. In the first step, tartaric acid based hydroxyl terminated polyesters with various alkane diols were prepared and then, in a second step, a chain-coupling approach using hexamethylene diisocyanate was employed on the synthesized polyesters to prepare a series of chain-coupled polyesters. The number-average molecular weights (Mn) of the polyesters were found to vary in the range (4.8 − 28.1) × 103 g mol−1. Thermomechanical studies demonstrate that the storage modulus of the chain-coupled polyesters decreases with increasing polymethylene chain length which is attributable to enhanced flexibility. The isolation of bacteria on medium containing polymer as the sole source of carbon indicates the ability of the synthesized polyesters to be taken up by microorganisms for growth. © 2013 Society of Chemical Industry

Atom-Economic, Metal- and Halogen-Free Synthesis of Podands: α,ω-Diphosphines and Their Chalcogenides Separated by Alkane Diol Spacers

Secondary phosphines and phosphine chalcogenides add to the divinyl ether of α,ω-alkane diols regio- and chemoselectively under free-radical conditions (UV irradiation or AIBN, 2:1 reactants molar ratio) to give anti-Markovnikov diadducts in good to excellent yields (65–98%).

Synthesis and properties of thermotropic liquid-crystalline polyesters containing 9,10-diphenylanthracene moiety in the main chain

We synthesized thermotropic liquid-crystalline polyesters in which 9,10-diphenylanthracene moieties are incorporated into the main chain type of polyester forming the chiral smectic C (Sm C*). The polymers were prepared by the isopropyltitanate-catalyzed reaction of biphenyldicarboxylic acid and the corresponding diols, with different ratios of diol of 9,10-diphenylanthracene moiety to the alkane diols (1, 5, and 10 mol %) under nitrogen atmosphere. The polymers exhibited thermotropic liquid crystals despite the presence of a bulky diphenylanthracene moiety in the main chain. The circular dichroism spectra revealed that a Sm C* phase was formed in the polymer with 1 mol % of anthracene moiety, although only an Sm A phase was formed in the other polymers. This is the first example of a Sm C* polyester containing a diphenylanthracene moiety in the main chain. Furthermore, we measured the optical properties of the polymers and found that they exhibited very high fluorescent efficiency. The fluorescence spectra of the thin film differed from that of a CH2Cl2 solution.

Synthesis and characterization of copolyesters based on tartaric acid derivatives

A series of aliphatic copolyesters based on naturally occurring l-tartaric acid amenable to facile post-polymer modification have been synthesized and characterized. The hydroxyl groups of the tartaric acid were protected and copolyesters were synthesized by taking different feed molar ratio of dimethyl 2,3-O-isopropylidene tartarate and dimethyl succinate with 1,6-hexanediol. Then, a series of copolyesters were synthesized by taking equal feed molar ratio of dimethyl 2,3-O-isopropylidene tartrate and dimethyl succinate or dimethyl adipate with different alkane diols. The acetal protecting groups were then selectively hydrolyzed to prepare a new series of copolyesters with pendant hydroxyl groups along the copolymer chain. The number average molecular weights (Mn) of the copolymers were found to vary in the range of 3.7–8.4 × 103 g mol−1. The hydroxy copolyesters show higher glass transition (Tg) and melting (Tm) temperatures as compared to isopropylidene copolyesters and the Tg varies from −8.0 to −48.2 °C depending on the feed ratio of the comonomers. The hydrolytic degradation studies of copolyesters revealed that hydroxyl copolyesters degrade faster than isopropylidene copolyesters.

Theoretical Calculation of the OH Vibrational Overtone Spectra of 1-n Alkane Diols (n = 2–4): Origin of Disappearing Hydrogen-Bonded OH Peak

In this theoretical study, we simulated the vibrational overtone spectrum of ethylene glycol (EG), 1-3 propanediol (PD), and 1-4 butanediol (BD). Using the local mode model along with the potential energy curve and dipole moment function calculated by B3LYP/6-31+G(d,p) and QCISD/6-311++G(3df,3pd), we obtained the theoretical peak position and integrated absorption coefficient. Furthermore, the vibrational spectra was simulated using a Voigt function using homogeneous and inhomogenous width obtained from quantum chemical calculation methods. Previously, Howard and Kjaergaard recorded the second and third overtone photoacoustic spectra of the three aforementioned alkane diols in the gas phase and observed that the intramolecular hydrogen bonded OH peak becomes difficult to observe as the intramolecular hydrogen bonding strength increased, that is, as the chain length was increased. In this paper we show that the disappearance of the hydrogen-bonded OH peak for the OH stretching overtone excitation for BD is partly due to the increase in homogeneous width due to the increase in the hydrogen bond strength and partly due to the decrease in the relative population of the intramolecular hydrogen-bonded conformers as the chain length is increased. This latter feature is a consequence of the unfavorable strained geometry needed to form the intramolecular hydrogen bond in longer alkane chains.

1H NMR study of through-bond and through-space effects in the hetero-association of pyridine with alkane diols, Erratum to poc. 1716

This paper (DOI 10.1002/poc.1716) was published online on 18 June 2010 and afterwards included in the February 2011 issue of the journal (vol. 24, no. 2, pp 129-139).

1H NMR study of through-bond and through-space effects in the hetero-association of pyridine with alkane diols

The 1H NMR titration method is used to investigate through-space and through-bond effects on the association of diols with pyridine in benzene. Alkan-1,n-diols (n goes from 2 to 10), DL and meso isomers of butan-2,3-, pentan-2,4- and hexan-2,5-diols, two adamantane diols and a bicyclo[2.2.2]octane diol are compared with alkanols. The –CH2OH groups of the tri- and bicyclic compounds behave as if they were independent, with limiting OH proton shifts (at very low concentration) and both the first and the second association constants similar to those of a primary alcohol. In contrast, the alkane diols, with n = 2–4, display unusually high limiting shifts, ranging from 1.0 to 1.5 ppm (2.1 ppm for one methyl-substituted diol). For these diols the first dissociation constant and the sum of the OH proton shifts in the 1:1 pyridine: diol complex are enhanced. This may be attributed to small cooperative effects, implying intramolecular hydrogen bonding, for n = 3 and 4, but for n = 2 a through-bond effect accounts for most of the increase. Substituent interaction falls off sharply for n = 5 and is practically negligible for n = 10, for which the second association constant is close to the first. A sterically hindered BiEDOT diol, 2,2′-bis{(3,4-ethylenedioxythienyl)-5-[3-(2,2,4,4-tetramethylpentan-3-ol)]} behaves like the polycyclic compounds, with the two C(t-Bu)2OH groups independent. Copyright © 2010 John Wiley & Sons, Ltd.

Theoretical study on the effect of intramolecular hydrogen bonding on OH stretching overtone decay lifetime of ethylene glycol, 1,3-propanediol, and 1,4-butanediol

It is well known that the existence of hydrogen bonds causes the vibrational spectra for the donor OH bond to broaden. Most times this broadening is attributed to inhomogeneous contributions, however in this paper, we studied the homogeneous contribution coming from the decay lifetime of the OH stretching excitation. Alkane diol, which possesses an OH(b)OH(f) (b and f stand for hydrogen bonded and free, respectively) intramolecular hydrogen bond, provides us with a controllable molecule to systematically study the effect of intramolecular hydrogen bond on the decay rate of the OH vibrational excitation. In the present study we performed local mode vibrational calculation of gas phase ethylene glycol (EG), 1-3 propanediol (PD), and 1-4 butanediol (BD) using the potential energy curves calculated using B3LYP/6-31+G(d,p), MPW1PW91/6-311+G(2d,p), M06-2X/6-311+G(2df,2p), and MP2/6-311++G(3df,3pd) methods. In addition, we studied the dynamics of OH overtone excited state (Δv(OH) = 3, 4) for the two most stable conformers of the aforementioned diols using the direct dynamics calculation employing the B3LYP/6-31+G(d,p) method. From the trajectory simulations we showed that the decay lifetime from the donor OH(b) excitation decreases while that from the acceptor OH(f) excitation increases as we increase the intramolecular hydrogen bond strength in going from EG, PD, to BD. These results are consistent with the gas phase experimental results of Kjaergaard et al. where the OH(b) peaks, which are sharp for EG disappear for BD. From the detailed analysis on the trajectories, we observed that the decrease in decay lifetime for the OH(b) bond excitation originates from the increase in the energy flow to the OH(b)O torsion/bend motion, while the increase in lifetime for OH(f) bond is due to the fixing of the OH(f) geometry by accepting a donor hydrogen. Furthermore, by plotting the calculated red shift versus the decay lifetime we obtained the following relationship T(decay)(fs) = 343176(Δω(cm(-1)))(-1.36).

Short scale (6 h) temporal variation of sinking fluxes of planktonic and terrigeneous lipids at 200 m in the NW Mediterranean Sea

Abstract. Drifting sediment trap measurements were carried out at high temporal frequency in the northwestern Mediterranean Sea in the course of the DYNAPROC 2 campaign, during the transition between late summer to autumn conditions. Molecular biomarkers were analyzed in selected subsets of consecutive samples collected for 6 h at 200 m depth. Fluxes of n-alkanes, long-chain alkenones, sterols and steroid ketones show high variability between consecutive 6-h samples, comparable in range to seasonal variability. n-Alkane export ranges from 1.4 to 29.7μg m−2 d−1, fluxes of C37 alkenones varies from 0 to 14.2 μg m−2 d−1. Fluxes of sterols, steroid ketones and C30 alkane diol respectively range from 31 to 377, 2.2 to 46 and 0.3 to 9.3 μg m−2 d−1. Biomarker flux ranges are coherent with the relatively low primary production and the low export ratio encountered during the study. Molecular characteristics of biomarker composition is consistent with reworked algal and zooplanktonic organic matter. Lipid biomarker composition points to the dominance of haptophytes over dinoflagellates in the exported material, and to a minor contribution of diatoms and eustigmatophytes. The intrusion of coastal water at the study site was recorded by an enhanced imprint of higher plant n-alkanes. Two processes can be responsible for the pulses in biomarker flux: changes in the magnitude of particle flux (dry weight mass flux) and changes in the concentration of biomarkers in the particles. Concurrent variability in fluxes, significant Pearson correlations between fluxes of biomarkers of haptophytes, dinoflagellates, eustigmatophytes, zooplankton activity and higher plants (alkenones, dinosterol, alkyl diols, dehydrocholesterol, steroid ketones, p<0.01, n=31, suggest that the short term temporal variability of biomarker export fluxes depends primarily on the intensity of particle dry weight flux. Biomarker concentrations vary on a relatively narrower range than biomarker fluxes, indicating that changes in particle composition (due to degradation or change in source apportionment) has a weaker influence on flux variability. Thus, particle aggregation and sinking are key processes to explain the dynamic of biomarker export at a temporal scale of 6 h. None the less, abrupt changes of OC-normalized concentrations of biomarkers, in the time scale of 6 h, indicate that the exported particles composition also show short-time variability. Highest biomarker flux values recorded by the trap samples from 27 to 29 September correspond to highest values of zooplankton biomass integrated between the surface and 200 m. The decrease in primary production after the October wind events is echoed by minima in biomarker flux values. Despite these correspondences, the coupling between primary production and biomarker export is complex.