Predicting cetane numbers of n-alcohols and methyl esters from their physical properties

Cetane numbers (C#) for the homologous series of straight-chain, saturated n-alcohols, C₅−C₁₂ and C₁₄, were determined according to ASTM D 613. Measured C# ranged from 18.2–80.8 and increased linearly with carbon number (CN). Regression analyses developed equations that related various physical properties or molecular characteristics of these alcohols to calculated C#. The degree of relationship between measured and calculated C# was expressed as R². The decreasing order of the precision with which these properties correlated with C# was: boiling point (bp)>melting point (mp)>CN>heat of combustion (HG)>refractive index (n²⁰ _D)>density (d). This ranking was based upon R² (0.99–0.96) and the Average % error (2.8–7.2%). C# were also determined for straight-chain homologs of saturated methyl esters with CN of 6, 10, 12, 14, 16 and 18. C# ranged from 18.0–75.6 and increased curvilinearly with CN. Equations were also developed that related physical properties of these esters to C#. The precision with which these properties correlated with C# was: bp>viscosity (V)>heat of vaporization (HV)>HG>CN>surface tension (ST)>mp>n²⁰ _D>d. R² ranged from 0.99 for bp to 0.98 for d. Equations for the alcohols were linear or quadratic, while equations for the esters were linear, quadratic or cubic based upon statistical considerations that included a Student’s t-test. With related physical properties and these equations, accurate predictions of C# can be made for saturated n-alcohols and methyl esters.     

Lubricity-Enhancing Low-Temperature Diesel Fuel Additives

Branched chain alkyl esters have lower crystallization temperatures than those with straight chain headgroups. We investigated the effect of branched chain headgroups on the cold flow properties and lubricity of alkyl esters. Commercial grade canola methyl ester was transformed into branched chain alkyl esters through a two or three-stage base-catalyzed transesterification reaction with 1-methoxy-2-propanol and 3-methyl-1-butanol. Conversion rates between 85 and 95% were achieved. The alkyl esters exhibited improved cold flow properties. The pour points were reduced from −12 to −27 °C as a result of incorporating branched headgroups. Addition of 0.1 or 0.2% (v/v) 1-methoxy-2-propyl alkyl ester improved the lubricity of a commercial pre-production ultra low sulfur diesel (ULSD) fuel, as determined by increased lubricity number and reduced wear scar diameter. The inclusion of methyl-tert butyl ether or ethanolamides additives to ULSD containing alkyl esters had an antagonistic effect on lubricity. The branched-chain alkyl esters have the potential to be used as lubricity-enhancing and low-temperature fuel additives.     

Properties, composition, and analysis of grain sorghum wax

Grain sorghum wax has been judged to be a potential source of natural wax with properties similar to carnauba wax. Approximately 0.16–0.3% (w/w) wax can be extracted from grain sorghum depending on the efficiency of the organic solvents. Although the melting points of carnauba wax and sorghum wax are similar, i.e., 78–86 and 77–85°C, respectively, they differ in acid values, i.e., 2–10 and 10–16, respectively, and saponification numbers, i.e., 77–95 and 16–49, respectively. Improved knowledge of the properties, composition, and analysis of grain sorghum wax would assist in efforts for industrial application of this product. Major components of sorghum wax are hydrocarbons, wax esters, aldehydes, free fatty alcohols, and FFA. The hydrocarbons consist mainly of C₂₇ and C₂₉, and the aldehydes, alcohols, and acids are mainly C₂₈ and C₃₀. The wax esters are mostly esters of C₂₈ and C₃₀ alcohols and acids.     

Molecular species of wax esters in jaw fat of atlantic bottlenose dolphin,Tursiops truncatus

The jaw fat of the Atlantic bottlenose dolphin (Tursiops truncatus) contains unusual wax esters which can be separated into short chain (<C₂₄) and long chain (>C₂₄) fractions by thin layer chromatography. The short chain wax esters (28 wt. %) have been characterized as a 72∶24∶4 mixture of isovaleroyl, isobutoryl, and 2-methylbutyrol, esters of C₁₄–C₁₈ n- and iso-alcohols. The intact <C₂₄ esters have been resolved into individual molecular species by gas liquid chromatography on open-tubular polyester columns. The long chain wax esters (12 wt. %) contain C₁₀–C₂₂ n- and iso-acids esterified to the same C₁₄–C₁₈ n- and iso-alcohols. Gas liquid chromatography of the intact, hydrogenated >C₂₄ esters on a short JXR column has characterized them according to carbon number and the number of methyl branches they contain.     

Convenient preparation of fatty ester cyclic carbonates

The cyclic carbonate moiety finds many industrial applications because of its unique chemistry and properties. Phosgene, a highly toxic and corrosive reagent, has been utilized in the past to prepare low yields of fatty ester compounds ( 1 ) that contain a five‐membered cyclic carbonate group. Herein, we show (CH₃)₄N^+?HCO₃, tetramethylammonium hydrogen carbonate (TMAHC), to react efficiently with methyl or 2‐ethylhexyl 9(10)chloro‐10(9)‐hydroxyoctadecanoate at 50–55 °C to give methyl or 2‐ethylhexyl 8‐(2‐oxo‐5‐octyl‐1,3‐dioxolan‐4‐yl)octanoate, 1a and 1b , respectively. These fatty acid ester carbonates were isolated in good yields ranging from 84% to 91% after purification by vacuum distillation. The purified fatty ester carbonate compounds were characterized by ¹H and ¹³C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gas chromatography‐mass spectrometry using electron impact ionization and positive chemical ionization techniques. This work demonstrates that the five‐membered cyclic carbonate ring can be effectively introduced onto the alkyl chains of fatty acid esters using fatty ester chlorohydrins and (CH₃)₄N^+?HCO₃ chemistry. The well‐known lubricating and polymeric properties of the carbonate moiety make these interesting cyclic oleochemical carbonates potential candidates for industrial lubricant, plasticizer, or polymer applications.     

Correlation of heats of combustion with empirical formulas for fatty alcohols

Gross heats of combustion (Hg) for the homologous series of saturated fatty alcohols C₁₀–C₂₂ were measured in a Parr adiabatic calorimeter according to ASTM D240 and D2015. The measured values for these alcohols ranged from 1582 to 3453 kg-cal/mole. We developed equations that related carbon number (CN) or chain length, electron number (EN) or number of valence electrons and molecular weight (MW) to calculated Hg by linear regression analysis (LINREG). These equations are: Hg=26.00+155.60 CN; Hg=26.00+25.94 EN; and Hg=−172.2+11.00 MW. R squared values for all three equations were 0.99. The results obtained with LINREG were compared to a literature method. Comparisons were made for both the fatty alcohols above and C₁–C₅, C₇, C₈ and C₁₆ alcohols of the literature method. For the former alcohols there was no difference in accuracy or precision between the two methods. For the latter alcohols LINREG was both more accurate and precise. Measured Hg vs. chain length for C₁–C₂₂ alcohols showed a perfect linear relationship. Thus, knowing chain length, Hg can be predicted accurately for alcohols in this range. Presented in part at the AOCS meeting in New Orleans, LA, in May 1987.     

α-Sulfonated fatty acid esters: I. Structural effects of sodium α-sulfonated fatty acid higher alcohol esters on surface-active properties and emulsification ability

The surface-active properties and emulsification ability of sodium α-sulfonated fatty acid esters, C_mH_2m+1CH-(SO₃Na)COOC_nH_2n+1, were studied as a function of the hydrophobic alkyl chainlength in the fatty acid (m=8−16) and the alcohol (n=8−18). As a result, it was discovered that sodium α-sulfonated fatty acid esters have a structural effect on the Krafft point different from that of amphiphiles with short alkyl chains. Moreover, some of the α-sulfonated fatty acid esters have quite low interfacial tensions, as well as non-foaming properties, which depend upon the total (m+n) number of carbon atoms in the alkyl chains.     

Potential synthetic lubricants: Esters of C18-saturated cyclic acids

A series of 16 esters of C₁₈-saturated cyclic acids (HCal) were prepared, and partial evaluation showed that several have qualities that recommend them as potential low-temp lubricants. Starting materials used were primary, straight, and branched chain alcohols C₄–C₇; perfluoro alcohols; phenol; cyclohexanol; and C₁₈-saturated cyclic alcohols prepared from cyclic acids. Viscosities were measured at −40, 100, and 210F. Their viscosity indexes ranged from 26 to 143. Pour points or melting points of the esters ranged from −27 to −96F. The oxidative stability of these esters measured at 347F according to a modification of the test method for military specification MIL-L-7808 was in nearly all cases equal or superior to the control bis-2-ethylhexyl sebacate. More severe oxidation tests showed the esters of HCal to be slower than the control in the development of acidic decomposition products. Presented at AOCS meeting, New Orleans, La., April 1964. A laboratory of the No. Utiliz. Res. and Dev. Div., ARS, USDA.     

Glucamine-based gemini surfactants I: Gemini surfactants from long-chain <Emphasis Type="Italic">N</Emphasis>-alkyl glucamines and α,ω-diepoxides

N-Alkyl glucamines can be reacted with α,ω-diepoxides to yield gemini (dimeric) surfactants similarly to the reaction of glucamine with terminal epoxides. Under the conditions chosen for this work, epoxides were quantitatively converted in the presence of an equimolar amount of amine to gemini surfactants. Reactions could be carried out under mild conditions (70°C) in methanol, and products were obtained quantitatively by removing the solvent. The combination of N-octyl glucamine, N-decyl glucamine, or N-dodecyl glucamine with diepoxides of α,ω-diolefins having chain lengths of C₈, C₉, C₁₀, or C₁₄ resulted in gemini surfactants differing in spacer length and length of hydrophobic alkyl chains. Surface-active properties were studied by measuring surface tension and evaluating foaming properties. Tensiometric studies showed the reduction of surface tension down to 29–33 mN/m and critical micelle concentrations often in the range of 3–150 mg/L. Comparison of a selected gemini surfactant [1,8-bis(N-dodecyl glucamino-2,7-octane diol] with its corresponding “single surfactant” demonstrated the enhancement of surface-active properties afforded by the gemini structure.     

Chemical fixation of carbon dioxide to dimethyl carbonate from propylene carbonate and methanol using ionic liquid catalysts

The synthesis of dimethyl carbonate (DMC) through the transesterification of propylene carbonate (PC) with methanol was investigated by using imidazolium salt ionic liquid catalysts. 1-alkyl-3-methyl imidazolium salts of different alkyl group (C₂, C₄, C₆, C₈) and anions (Cl⁻, Br⁻, BF₄⁻, PF₆⁻) were used for catalysts. The reaction was carried out in an autoclave at 140–180°C under carbon dioxide pressure of 1.48–5.61 MPa. The imidazolium salts of shorter alkyl group, and more nucleophilic counter anion exhibited higher catalytic activity. The conversion of PC increased as CO₂ pressure and reaction temperature increased. Kinetic studies were also performed to better understand the reaction mechanism. This paper was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Synthesis and properties of N-(α-carboxyalkyl)acrylamide telomer-type surfactants having multihydrocarbon chains

N-(α-Carboxyalkyl)acrylamide telomer-type surfactants (xC _n−1 AmAc where n is alkyl chain length=6, 8, 10, 12; and x is degree of polymerization=3.3–13.1) were synthesized by the telomerization of monomer (C _n−1 AmAc) in the presence of the corresponding alkanethiol as a chain transfer agent and then investigated for their surface-active properties. xC _n−1 AmAc telomers lowered the surface tension of aqueous solutions that were at pH 9–10. The critical micelle concentrations (CMC) of the telomers were lower than those of the monomers with the same alkyl chain length, and the CMC values shifted to lower concentrations with both increasing alkyl chain length and polymerization degree. xC₉AmAc with x=3.3–6.3 gave the highest efficiencies in lowering the surface tension. The cross-sectional molecular areas per molecule of xC _n−1 AmAc telomers were smaller than the values estimated on the assumption that they are assemblies of C _n−1 AmAc monomer units. The foaming abilities and the foam stabilities were both in the orders of xC₇AmAc>xC₉AmAc>xC₅AmAc>xC₁₁AmAc. Mixtures of aqueous solutions of xC _n−1 AmAc telomers and toluene formed oil-in-water emulsions. The emulsion-stabilizing abilities were in the orders of xC₇AmAc>xC₅AmAc>xC₉AmAc=xC₁₁AmAc. The addition of Ca²⁺ to the mixed solutions of telomers and toluene resulted in formation of water-in-oil type emulsions. Thus, the surface-active properties of the telomers were influenced significantly by the alkyl chain length and the polymerization degree of the telomers. In addition, these properties could be correlated with the hydrophilic-lipophilic balance (HLB); the highest surface activities were observed by using xC _n−1 AmAc with HLB of 14–18.     

Reductive Dehydration of Ethanol: A New Route Towards Alkanes

New reactions, catalytic ethanol reductive dehydration into alkanes C₃–C₁₀ and cross-coupling of ethanol with cyclopentanol into alkyl substituted cycloalkanes, were studied. The reductive dehydration of ethanol was carried out at 350 °C and 50 atm of Ar. The intermetallic hydrides with different hydrogen content, industrial Pt/γ-Al₂O₃ and reduced molten promoted iron catalysts were used as catalysts. The yield of alkanes varies depending on acid/base additives. The conversion of ethanol and the yield of higher alkanes increase as the hydrogen content in the intermetallic material decreases. When MgO is used as additive ethanol converts mainly into iso-alkanes. The content of iso-alkanes in the C₅–C₁₀ fraction reaches 92%. The cross-coupling of ethanol with cyclopentanol over the catalytic compositions consisting of intermetallic hydride and Pt/γ-Al₂O₃ and reduced molten promoted iron afforded cyclic alkyl substituted hydrocarbons. Dedicated to Professor Sir John Meurig Thomas in the recognition of his pioneering contributions in catalysis.     

Synthesis and characterization of dialkyl carbonates prepared from mid-, long-chain,and guerbet alcohols

A series of organic carbonates derived from mid-, long-chain, and Guerbet alcohols were synthesized in good yield (69–80% isolated yields after purification by distillation or recrystallization) though a carbonate interchange reaction by heating the linear or Guerbet alcohols with diethyl carbonate in the presence of catalyst, n-dibutyltin oxide. The carbonates were isolated by Kügelrohr distillation or recrystallization from acetone and characterized using FTIR, GC, ¹H and ¹³C NMR spectroscopy, and GC-MS. El and positive Cl mass-spectral techniques were used to characterize the carbonates. Such materials are currently of commercial interest as lubricants and additives in various industrial applications.     

Cuticular lipids of insects: V. Cuticular wax esters of secondary alcohols from the grasshoppersMelanoplus packardii andMelanoplus sanguinipes

Wax esters of secondary alcohols constitute 18–20% of the cuticular lipid extract ofMelanoplus packardii and 26–31% of the cuticular lipids ofMelanoplus sanguinipes. The total number of carbons in the wax esters range from 37–54 with 41 predominating in both species. The fatty acids ofM. packardii wax esters are 16∶0, 18∶0, 14∶0, 20∶0 and 12∶0 in decreasing quantity. The fatty acids ofM. sanguinipes wax esters are 18∶0, 20∶0, 16∶0 22∶0, 14∶0, 19∶0 and 17∶0 in decreasing quantity. The secondary alcohols from the wax esters ofM. packardii are C₂₅, C₂₃ and C₂₇ in decreasing quantity, and the secondary alcohols of theM. sanguinipes are C₂₃, C₂₅, C₂₁, C₂₇, C₂₄, C₂₂ and C₂₆ in decreasing quantity. Each secondary alcohol consists of two to four isomers with the hydroxyl group located near the center of the chain. Montana Agriculture Experiment Station, Journal Series No. 332.     

A process for the preparation of food-grade rice bran wax and the determination of its composition

A two-step method was developed for the preparation of food-grade wax. The first step involved the solventdefatting of crude wax, which gave a dark brown, dry, powdered wax with a m.p. of 75–79°C. The major impurity in the defatted wax was the dark brown resinous matter. In the second step, the resinous matter was removed by bleaching with sodium borohydride in isopropanol. This step yielded a pale yellow, odorless wax with purity higher than 99% and with a m.p. of 80–83°C. The resinous matter was a mixture of aliphatic aldehydes, fatty alcohols, and FA. High-temperature GC analysis of the purified rice bran wax indicated that it contained 11 major and 9 minor types of saturated wax esters. The major and minor peaks contained C₄₄–C₆₄ and C₄₅–C₅₉ wax esters, respectively. Rice bran wax was mainly a mixture of saturated esters of C₂₂ and C₂₄ FA and C₂₄ to C₄₀ aliphatic alcohols, with C₂₄ and C₃₀ being the predominant FA and fatty alcohol, respectively. The alcohol portion of the wax esters also contained small amounts of branched and odd carbon number fatty alcohols.     

Fuel properties and nitrogen oxide emission levels of biodiesel produced from animal fats

FAME of lard, beef tallow, and chicken fat were prepared by base-catalyzed transesterification for use as biodiesel fuels. Selected fuel properties of the neat fat-derived methyl esters (B100) were determined and found to meet ASTM specifications. The cold-flow properties, lubricity, and oxidative stability of the B100 fat-derived fuels also were measured. In general, the cold-flow properties of the fat-based fuels were less desirable than those of soy-based biodiesel, but the lubricity and oxidative stability of the fat-based biodiesels were comparable to or better than soy-based biodiesel. Nitrogen oxide (NO_x) emission tests also were conducted with the animal fat-derived esters and compared with soybean oil biodiesel as 20 vol% blends (B20) in petroleum diesel. The data indicated that the three animal fat-based B20 fuels had lower NO_x emission levels (3.2–6.2%) than did the soy-based B20 fuel.     

Synthesis and Physicochemical Properties of Low Viscosity 2-Ethylhexyl Alkyl Ethers Made from Palm-Based Esters as Potential Biolubricant

A series of 2-ethylhexyl alkyl ethers (EHAE) are synthesized from palm-based esters via a one-step reaction under mild reaction conditions for potential usage as biolubricant. In this work, 2-ethylhexyl esters with varying fatty acid chain lengths are reacted with 1,1,3,3-tetramethyldisiloxane (TMDS), catalyzed by indium bromide (InBr₃) at 40 °C to afford EHAE with lauryl, palmityl, stearyl, and oleyl alkyl chain with 55–68% isolated yield. These compounds are characterized using Fourier-transform infrared (FTIR) and NMR spectroscopic methods and are evaluated for their viscosity, thermal, cold-flow, oxidative, and anti-wear properties. The synthesized EHAEs demonstrate low viscosity (1.65–2.55 cSt at 100 °C) with excellent viscosity indices (130–182). These EHAEs show comparable wear scar diameter (0.6–1.0 mm) in comparison with commercial mineral oil base stock (group I SN150) in the four-ball wear test. Thermal-oxidative investigation of the EHAE reveals that the thermal degradation temperatures are in the range of 200–250 °C and oxidation onset temperatures are between 165 and 184 °C. Among the EHAEs, 2-ethylhexyl lauryl ether with the shortest alkyl chain has the lowest pour point of ?27 °C. The physicochemical properties of synthesized EHAEs indicate that they are potential as biolubricant base stocks. Practical Applications : The EHAEs produced from this work exhibit promising physicochemical and lubricity properties, which offer great potential to be used as lubricant base stock especially for internal engine oil application.     

Distinctive medium chain wax esters,triglycerides, and diacyl glyceryl ethers in the head fats of the pacific beaked whale,Berardius bairdi

Lipids were extracted from the mandibular fat body (jaw), the fatty forehead (melon), and the dorsal blubber of a Pacific beaked whale (Berardius bairdi) and separated into lipid classes by preparative thin layer chromatography. The head fats were mixtures of wax esters and triglycerides with a very small amount of diacyl glyceryl ether. The blubber fat contained 97% was ester and 3% triglyceride. Gas liquid chromatography (GLC) of the intact lipid classes indicated an unusually low C₂₆–C₃₀ range for most of the jaw and melon wax esters compared to the more normal C₃₂–C₄₀ molecules found in the blubber. Distinctive lower molecular weight C₂₄–C₄₀ triglycerides occurred in the head fats vs. the usual C₄₄–C₅₈ range in the blubber. Most diacyl glyceryl ethers were in the C₃₅–C₄₆ range, below the molecular weight of hexadecyldipalmitoyl glyceryl ether (C₄₈). GLC of the derived fatty acid methyl esters showed that the lower molecular weight neutral lipids in the head fats were due to high levels of iso-10∶0, n−10∶0, iso-11∶0, iso-12∶0, n−12∶0, and iso-13∶0 acids. The wax ester fatty alcohols and the alkoxy chains of the glyceryl ethers were mostly the C₁₄–C₂₀ chain lengths commonly observed in marine organisms. The distinctive medium chain neutral lipids in the jaw and melon fats of this whale may be related to the postulated acoustical role of these tissues in echolocation.     

1,2-Isopropylidene Glycerol Carbonate: Preparation,Characterization, and Hydrolysis

Utilization of excess glycerol supplies derived from the burgeoning biodiesel industry is of major importance to the oleochemical industry as the economic viability of the biodiesel and oleochemical industries are closely linked to glycerol prices. Carbonates based on glycerol, such as glycerol carbonate, are gaining prominence due their simple preparation, interesting properties and chemistry. Herein, the synthesis, physical properties, and chemistry of an interesting glycerol-based carbonate (4, bis[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl] carbonate; 1,2-isopropylidene glycerol carbonate or solketal carbonate) is reported. Carbonate interchange reaction between solketal (isopropylidene glycerol) and diethyl carbonate in the presence of sodium methoxide catalyst gave solketal carbonate, 4, in 65–70% isolated yields. Carbonate 4 was characterized using Fourier transform infrared spectroscopy (FTIR), ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR), and gas chromatography–mass spectrometry (GC/MS). The kinematic viscosity at 40 °C, refractive index, and melting point of 4 were determined to be 26.7 mm²/s, 1.4460, and below −50 °C, respectively. Using a high frequency reciprocating rig (HFRR) testing apparatus neat 4 was shown to have lubricity properties similar to fatty acid esters. Hydrolysis of the isopropylidene groups converted carbonate 4 into polyol 6, bis(2,3-dihydroxypropyl) carbonate in good yields (84%). Carbonate polyol 6 was characterized by ¹H and ¹³C NMR and represents a potentially novel polyol component that may be useful in the syntheses of interesting carbonate containing esters and polymers. Disclaimer: Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Solubility and heat stability of fat-soluble derivatives of vitamin B6

Summary The heat stability of several fatty acid esters of pyridoxine and their solubility in fats was tested. Short chain fatty acid esters of pyridoxine, such as pyridoxine triacetate, and long chain saturated fatty acid esters of the vitamin, such as pyridoxine tripalmitate were almost insoluble or had a rather limited solubility in fats. An improvement in solubility was observed when pyridoxine was partially esterified with palmitic acid, fully esterified with a long chain unsaturated fatty acid, such as linoleic acid, or when it was esterified with a fatty acid of intermediate chain length (C₆, C₈ or C₁₀). Free pyridoxine and the acetate were destroyed by heat when mixed in a fat and heated at 205–210°C. A profound improvement in heat stability in pyridoxine was noted when one palmitoyl group was introduced, and the ester became completely stable when it was fully esterified with a saturated fatty acid of C₁₀ or longer chain length. Portion of a thesis presented by T. Sakuragi as partial fulfillment of the requirement for the degree of Doctor of Philosophy in Food Technology. This work was supported by research grant No. A-257 from the National Institute of Health, U. S. Public Health Service, Department of Health, Education and Welfare. Presented at the 29th annual meeting of the American Oil Chemists’ Society, Oct. 10–12, 1955, Philadelphia, Pa.