Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 37

Liczba wyników na stronie
first rewind previous Strona / 2 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  alcohols
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 2 next fast forward last
EN
This paper presents the effect of selected alcohols on the fluidity of liposome membranes obtained in sonication of DPPC lecithin. Using the EPR technique, the duality of propanol, n-butanol and pentanol on the behaviour of the aqueous dispersion of liposomes was demonstrated. It was shown that after exceeding a certain concentration, these alcohols initiate dispersion foaming, leading to phase separation: liposome dispersion - lipid foam. The influence of the shape of the molecule and the length of hydrocarbon chains on the effectiveness of destabilisation of the structure of lipid membranes was indicated.
2
PL
Od setek lat w życiu człowieka przeplata się alkohol, który był i jest spożywany w różnych formach. W życiu codziennym pod nazwą „alkohol” kryje się jeden związek - etanol [1, 2]. Jednak w aspekcie chemicznym alkohole tworzą liczną grupę substancji, a spożycie wielu z nich może spowodować poważny uszczerbek na zdrowiu a nawet doprowadzić do zgonu człowieka - do takich właśnie alkoholi należy metanol [2]. Porównując etanol do metanolu pod kątem budowy chemicznej, posiada on dodatkowo jedną grupę metylenową, ale nie jest możliwe organoleptyczne rozróżnienie tych dwóch związków. Podobieństwo w smaku i zapachu oraz brak barwy mogą spowodować omyłkowe spożycie alkoholu metylowego [2, 3]. W procesie rozkładu metanolu w ludzkiej wątrobie powstają inne metabolity niż w przypadku rozkładu etanolu co jest spowodowane wcześniej wspomnianą różnicą w budowie obu związków [1, 2, 4]. Metabolity powstałe w wyniku rozkładu alkoholu metylowego mogą powodować ostrą niewydolność nerek, uszkodzenie mięśnia sercowego i wątroby, całkowitą ślepotę, a nawet śmierć [2]. Osoby zatrute metanolem wymagają natychmiastowej pomocy medycznej, jednak pierwszą pomocą może stanowić alkohol etylowy - substancja psychoaktywna, uzależniająca, a w nadmiernych ilościach zagrażająca życiu [2-5].
EN
Alcohol has been intertwined in human life for hundreds of years and has been consumed in various forms. In everyday life, the name "alcohol" covers one compound - ethanol [1, 2]. However, from the chemical point of view, alcohols form a numerous group of substances, and consumption of many of them may cause serious damage to human health or death - methanol is one of such alcohols [2]. Comparing ethanol to methanol from the chemical structure point of view, ethanol has additionally one methylene group, but it is not possible to distinguish organoleptically between these two compounds. The similarity in taste and smell and the lack of colour may cause mistaken ingestion of methyl alcohol [2, 3]. In the process of methanol decomposition, different metabolites are formed in the human liver than in the case of ethanol decomposition, which is due to the previously mentioned difference in the structure of both compounds [1, 2, 4]. The metabolites formed by methyl alcohol decomposition can cause acute renal failure, myocardial and hepatic damage, total blindness, and even death [2]. Individuals poisoned by methanol require immediate medical attention, but ethyl alcohol, a psychoactive, addictive, and life-threatening substance in excessive amounts, may be the first aid [2-5].
EN
Over the past 20 years quantitative measures of frother functions have been developed to try to replace such qualitative descriptors as “weak” and “strong”. One of these metrics is the critical coalescence concentration (CCC) that quantifies a frother’s ability to reduce bubble size; another is the concentration at minimum velocity (CMV) that quantifies a frother’s ability to reduce bubble rise velocity. The experimental procedure for the two measures is briefly outlined and the measures are shown to be related. Using CMV, based on more than 50 surfactants from the two main frother families, alcohols and polyglycols, the frother structure-property-function link is investigated. The structure variables were: in alcohols, alkyl chain length, and position of the methyl branch and hydroxyl group(s); and in polyglycols, alkyl chain length, and number of propylene oxide (PO) or ethylene oxide (EO) groups. On the argument that low CMV represents the desired outcome, the main findings are: the dominant effect of alkyl chain length in both alcohols and polyglycols; that for alcohols branched-chain isomers are superior to straight chain, with the best combination being OH at the terminus and the methyl branch as far away as possible; and for polyglycols, PO-based are superior to EO-based. Interpretation of these observations included the effect of structure on the following properties: surface activity, mass transfer rate, H-bonding, and molecule packing.
EN
Increasing the sustainability of individual transportation and replacing a part of fossil energy in traffic by renewable energy carriers are worldwide important objectives. Bioalcohols are generally recognized as one of very useful alternatives. The global share of bioethanol used for transportation is continuously increasing. Butanol, a four-carbon alcohol, is considered in the last years as an interesting alternative fuel, both for diesel and for gasoline application. Its advantages for engine operation are: good miscibility with gasoline and diesel fuels, higher calorific value than ethanol, lower hygroscopicity, lower corrosivity and possibility of replacing aviation fuels. In the present work, the emissions of two gasoline vehicles – with older and with newer technology – were investigated in dynamic-, stationary and cold start operation.
EN
The paper covers the mechanism of lubrication layer formation by fuels containing synthetic hydrocarbons and alcohols. Development of alternative fuels containing FAME, alcohols, and synthetic hydrocarbons has increased the interest in the mechanism of lubrication of fuelling systems parts. Fuel lubricity tests have been conducted using the HFRR and BOCLE testing rigs. Fuels under testing, both for CI engines and for aviation turbine ones, contained synthetic components: saturated hydrocarbons both of even and odd number of carbon atoms, and butanol, isomers. These components have been added to conventional fuels, such as diesel fuel and Jet A-1 fuel at the concentration of 0–20% (V/V). All fuels under testing contained commercially available lubricity improvers (carboxylic acid). Test results were analysed using model αi described in [L. 6, 7]. As a result of the analysis, it has been found that the liquid phase, which is a lubricating film, should contain agglomerates or molecular clusters responsible for the transport of energy introduced into lubricating film by electrons emitted from metal surface. The mechanism enabling a description of the effect of base fuel without lubricity improvers on efficiency of such additives has been suggested.
PL
Przedmiotem artykułu jest mechanizm tworzenia warstwy smarującej przez paliwa zawierające syntetyczne węglowodory i alkohole. Rozwój paliw alternatywnych spowodował wzrost zainteresowania mechanizmem smarowania elementów układów zasilania silników. Badania smarności paliw prowadzono z użyciem aparatów HFRR i BOCLE. Badane paliwa do silników o ZS i paliwa do turbinowych silników lotniczych zawierały trzy serie syntetycznych komponentów: węglowodory parafinowe o parzystej liczbie atomów węgla, węglowodory parafinowe o nieparzystej liczbie atomów węgla oraz izomery butanolu. Powyższe syntetyczne komponenty były dodawane do mineralnych paliw: oleju napędowego i paliwa Jet A1 w ilości 0–20% (V/V). Wszystkie badane paliwa zawierały komercyjnie dostępne dodatki smarnościowe (kwas karboksylowy). Wyniki badań eksperymentalnych były analizowane z zastosowaniem modelu αi opisanego w publikacjach [L. 6, 7]. W rezultacie przeprowadzonej analizy stwierdzono, że faza ciekła – film smarny powinna zawierać aglomeraty lub klastry molekularne, które są odpowiedzialne za transport energii wprowadzanej do filmu smarnego przez elektrony emitowane z powierzchni metalu. Zaproponowano mechanizm, który może wyjaśnić wpływ paliwa bazowego (bez dodatków smarnościowych) na efektywność działania dodatków smarnościowych.
EN
The o-Ps mean lifetime value in liquids decreases in the presence of the paramagnetic oxygen molecules via the ortho-para conversion process. This effect was observed for several organic samples composed of carbon and hydrogen atoms differing in the arrangement of atoms forming the molecule, e.g. n-alkanes, alcohols, branched isomer of alkane, cycloalkane. The usually observed tendency of the o-Ps lifetime value to be an increasing function of temperature (in the case of measurements performed in vacuum) changes to a decreasing one in the presence of O2 dissolved in the sample. The difference between the o-Ps lifetimes measured in samples in vacuum and in the presence of O2 increases with the distance from the melting point. The ortho-para constant rate λconv was estimated to be ~130 μs–1 at 300 K for three compounds investigated.
EN
Ultrasonic velocities and densities of the binary liquid mixtures of benzene with 1-propanol, 2-propanol, 1-butanol, 2-butanol and 3-butanol at 303.15 to 318.15 K, over the entire composition range were measured. The theoretical values of ultrasonic velocity were evaluated using the Nomoto’s Relation (NR), Ideal Mixture Relation (IMR), Free Length Theory (FLT) and Collision Factor Theory (CFT). The validity of these relations and theories were tested by comparing the computed sound velocities with experimental values. Further, the molecular interaction parameter (á) was computed by using the experimental and the theoretical ultrasonic velocity values. The variation of this parameter with composition of the mixtures has been discussed in terms of molecular interaction in these mixtures.
PL
Przedstawiono wyniki pomiaru emisji toksycznych składników z silnika rolniczego o zapłonie samoczynnym typu Perkins 1104C-44 z wtryskiem bezpośrednim, zasilanego paliwem roślinnym RME (estry metylowe kwasów oleju rzepakowego) oraz jego mieszankami z trzema rodzajami alkoholi pochodzenia roślinnego. Wykazano, że rodzaj paliwa o różnych właściwościach fizykochemicznych ma istotny wpływ na emisję toksycznych składników spalin.
EN
Com. Me ester of rapeseed oil fatty acids and its mixt. with BuOH, EtOH or i-PrOH (10% of each) were used as fuel for an agricultural diesel engine with direct injection in a std. 11-step test to study the content of CO, hydrocarbons, NOx and particulate matter in the off-gas. The addn. of EtOH to the gas oil resulted in the highest decrease in the NOx and particulate matter contents, while the hydrocarbon and CO contents were lowest in an case of alc.-free oil.
EN
Five ketones, both unsaturated and saturated, which have phenyl and/or t-butyl groups as substituents located at the end of a molecule have been prepared. They were used as starting materials in the synthesis of ethylene and propylene acetals, alcohols and their acetates. Thirteen from twenty three synthesized compounds (all ethylene and propylene acetals, an alcohol and two acetates) have not been described yet. The odour properties for all the prepared compounds have been determined. Most of them have pleasant, fruity-floral odours.
EN
The new QSPR correlation equation was developed for the estimation of the boiling points of three families of oxygen containing aliphatic compounds. This equation includes contributions depending on the total number of carbon atoms forming a molecule and the fragment term represented as an explicit function of some basic topological charateristics of the molecular structure. The original mathematical form for description of non-linear contribution is suggested. A three-parameter correlation with the squared correlation coefficient r2 = 0.9991 gives excellent predictions for 116 oxygenated compounds, with mean square deviation s = 2.09 K and mean error of plus or minus 1.66 K. All the parameters in volved in these equations can be obtained solely from the chemical structure.
12
Content available remote Anodowe właściwości żelaza w metanolowych roztworach elektrolitów
PL
Praca prezentuje badania elektrochemicznych właściwości żelaza w bezwodnych metanolowych, roztworach chloranu (VII) litu i chlorku litu. Badania były prowadzone za pomocą woltametrii cyklicznej. W roztworach nadchloranu litu, żelazo ulega pasywacji. Dodatek chlorku litu ogranicza zakres pasywny do potencjału stabilności związków Fe2+ (< -0,2 V). W pracy zaproponowano mechanizm utleniania żelaza w układzie alkohol - LiClO4 - LiCl.
EN
The paper presents the study of electrochemical properties of iron in anhydrous methanol, ethanol and n-propanol solutions of lithium perchlorate and lithium chloride. Investigations were performed by means of linear sweep voltammetry. In alcohol - lithium perchlorate solutions iron undergoes passivation. An addition of lithium chloride limits passive range to the potential range of stability of Fe2+ compounds (< -0.2V). The mechanism of iron oxidation in alcohol -LiClO4 - LiCl system has been proposed.
PL
Zbadano wydajność wytwarzania wodoru z mieszaniny lotnych kwasów tłuszczowych z etanolem, propanolem i propano-1,3-diolem w obecności Rhodobacter sphaeroides. Substancje te nie inhibitowały wzrostu bakterii i produkcji wodoru, jednakże propano-l,3-diol nie był metabolizowany. Maksymalna ilość wodoru, 5,2 dm3/dm3, powstała w podłożu z glutaminianem sodu, a najmniejsza w obecności 10 mM jonów amonowych.
EN
Efficiency of hydrogen production from the mixture of volatile fatty acids with ethanol, propanol and propane-l,3-diol in the presence of Rhodobacter sphaeroides was measured. These substances did not inhibit bacterial growth and hydrogen production. However, propa-ne-l,3-diol was not metabolized. The maximum amount of hydrogen (5.2 dm3/dm3) was produced in the medium with sodium glutamate, while the smallest - in the presence of ammonium ions.
14
Content available remote Eteryfikacja alifatycznych alkoholi wielowodorotlenowych chlorkiem allilu
PL
Przedstawiono wyniki badań eteryfikacji gliceryny, trimetylolopropanu i pentaerytrytu chlorkiem allilu w obecności wodnego roztworu wodorotlenku sodu i czwartorzędowej soli amoniowej (Bu4N+J-, Bu4N+HSO4-) jako katalizatora przeniesienia fazowego. Stwierdzono, że w syntezie powstaje mieszanina produktów eterowych z wydajnością 51–60% mol. dla reakcji z gliceryną i pentaerytrytem oraz z prawie ilościową wydajnością wynoszącą 99% mol. dla reakcji z trimetylolopropanem.
EN
Allyl chloride was used to etherify (i) glycerol, (ii) trimethylolpropane or (iii) pentaerythritol in aq. 47% NaOH over an ammonium salt (Bu4NI, Bu4NHSO4) as a phase transfer catalyst. In 4–6 hours at 60–70°C, (i) and (iii) gave 51–60% of ether products, selectivity 91%, with (i) tri (40%) and (iii) tri (31%) and tetraallyl ether (28%) as the major products. In 3 hours at 90°C, (ii) gave 99% of ether products with the diallyl deriv. (75%) as the major product. Diallyl ether was the by-product prepd. from diallyl alc. that formed reaction conditions.
15
Content available remote Effect of mono- and polyols on motion resistance in the steel-alumina system
EN
In this research an effect of alcohols applied as lubricants on motion resistance in the friction couple: steel-alumina was investigated. The tests were performed in a point contact: steel ball-ceramic disc (tribometer T- 11) under load of 40 N with sliding velocity 0.1 m/s. The test duration was 900 s. Pure mono- and polyhydric alcohols of various alkyl chain lengths were used as lubricants. The chemical structure of these alcohols was analysed to assess its influence on motion resistance. The effect of alkyl chain length, number of hydroxyl and methyl groups on the friction coefficient was assessed. The tests revealed significant influence of compound structure on motion resistance in steel-ceramics contact. Reduction of friction coefficient goes with increase of alkyl chain length in the row: ethanediol, propanediol, butanediol. The character of chemical interactions between the alcohol molecule and alumina surface can explain the action of alcohols in the steel-ceramics contact. One can suppose that creation of bonds between hydrogen atoms from hydroxyl groups and oxygen atoms present at ceramic surface results in chemical adsorption.
PL
W pracy badano wpływ alkoholi, stosowanych jako substancje smarowe, na opory ruchu w skojarzeniu materiałowym: stal-tlenek aluminium. Badania prowadzono w styku skoncentrowanym: stalowa kulka-tarcza ceramiczna (tribometr T- 11), przy obciążeniu 40 N i prędkości poślizgu 0,1 m/s. Czas testu wynosił 900 s. Substancję smarową stanowiły czyste alkohole mono- oraz polihydroksylowe, o różnej długości łańcucha alkilowego. Analizowano wpływ struktury chemicznej alkoholu na opory ruchu. Badano zależność współczynnika tarcia od długości łańcucha alkilowego, liczby grup hydroksylowych oraz liczby grup metylowych w cząsteczce alkoholu. Przeprowadzone badania wykazały istotny wpływ budowy związku na opory ruchu w skojarzeniu stal-ceramika. Obserwowano obniżenie współczynnika tarcia wraz ze wzrostem długości łańcucha alkilowego w szeregu: etanodiol, propanodiol, butanodiol. Również wzrost liczby grup hydroksylowych wpływał na obniżenie oporów ruchu. Działanie alkoholi w obszarze tarcia stal-ceramika może wynikać z chemicznego charakteru oddziaływań cząsteczki alkoholu z powierzchnią ceramiki tlenkowej. Można przypuszczać, że badane związki ulegają adsorpcji chemicznej na powierzchni tlenku aluminium w wyniku tworzenia wiązań między atomami wodoru grup hydroksylowych a atomami tlenu obecnymi na powierzchni ceramiki.
PL
Przedstawiono wyniki badania procesu siarczanowania oksyetylenowanych alkoholi o różnej zawartości wolnego alkoholu. Użyte surowce otrzymano przez oddestylowanie części lżejszych frakcji z technicznych oksyetylatów alkoholu laurylowego o średnim stopniu oksyetylenowania 2 lub 3. Siarczanowanie oksyetylenowanych alkoholi prowadzono za pomocą kwasu chlorosulfonowego. Uzyskane siarczany zmodyfikowanych oksyetylatów wykazywały istotne różnice właściwości fizykochemicznych. Ponadto wykonano porównawczą ocenę przykładowych wyrobów chemii gospodarstwa domowego, gdzie zastosowano otrzymane siarczany.
EN
Tech.-grade ethoxylated C12–C14 (“lauryl”) alcs., av. ethoxylation deg. 2 or 3, were distd. over 150–213°C/15–20 mmHg to give distillates contg. 1.8–40.7% of the free alcs. The ethoxylates were sulfated 20 min with chlorosulfonic acid (1:1.05 by moles) at 30–35°C, ripened 20 min at 40–45°C, and neutralized to yield clear homogeneous sulfates. As the content of free alcs. in the ethoxylates was reduced, the resulting aq. solns. of the sulfates had a lower viscosity, a higher surface tension, a lesser gel formation, and a higher foam formation ability. The dishwashing agents and the shampoo bases prepd. from the sulfates showed no such simple relationships, except that the products contg. the sulfates prepd. from the 40.9% and 8.9% free alc. ethoxylates were much better.
EN
Internal pressure was calculated for some alcohols from experimental data on isothermal compressibility and isobaric coefficient of thermal expansion as well as by using of the mean molecular radius, in most cases from the speed of ultrasound data. The results differ quantitatively as well as qualitatively and suggest, that calculation of internal pressure by using of the mean molecular radius is incorrect (obtained values are unreliable and unacceptable).
18
Content available remote Application of biofuels to compression ignition engines
EN
In the paper a review of alternative fuels to compression ignition engines has been performed. Fuels, which presently are mostly used, are biofuels such as transesterified vegetable oils (FAME) and alcohols (bioethanol). Main part of the paper comprises the experimental investigation performed by the author at Politechnika Radomska. Comparison of emissions of the one - cylinder D.I. C.I. engine fuelled with rape oil methyl ester (RME) and dieselfuel (DF) at load characteristics has been carried out, showing, that results are comparable. Also comparison of emissions of the engine fuelled either with RME or DF and additionally by ethanol (E) injected to inlet port has been peiformated. In the case of this fuelling system better results have been obtained for RME and E application than these of DF and E: much lower emission of CO2 and smoke.
EN
t-Butyl methyl iminodicarbonate (3) can be easily alkylated with primary or secondary alcohols under Mitsunobu conditions (DIAD, TPP) to give the corresponding N-alkyl iminodicarbonates. Partial deprotection of the latter with methanolic potassium hydroxide affords N-Boc-amines (5) in good yields.
EN
The excess values of the molar adiabatic compressibility as well as adiabatic compressibility coefficeint were estimated for binary mixtures of 1,2-ethanediol+1-pentanol at the temperatures (293.15, 303.15, 308.15 and 313.15) K. Alsko deviations of the ultrasonic speed from the chosen additivity rules were determinated. Together with the previous result for T = 298.15K (E. Zorębski, Mol.Quant Acoust.,24 261-270 (2003)), the effect of temperature on speed of ultrasound and adiabatic compressibility is studied. It appears that both excesses decrease with increasing temprature whereas deviations of ultrasonic speed have opposite temperature dependencies.
first rewind previous Strona / 2 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.