Estimation of the Flash Points of Saturated and Unsaturated Hydrocarbons

Indian Journal of Engineering & Materials Sciences Vol. 19, August 2012, pp. 269-278

Estimation of the flash points of saturated and unsaturated hydrocarbons

M H Keshavarz* Department of Chemistry, Malek-ashtar University of Technology, Shahin-shahr P.O. Box 83145/115, Islamic Republic of Iran Received 26 May 2011; accepted 11 June 2012

This work introduces a novel, reliable and simple correlation for predicting the flash point of various types of saturated and unsaturated hydrocarbons containing cyclic and acyclic paraffins, olefins, alkynes and aromatic hydrocarbons. It is shown that the new method is based on the number of carbon and hydrogen atoms and some specific molecular moieties, which can easily be used for any types of hydrocarbons. The largest available experimental data consisting of 441 diverse hydrocarbons are used here in order to derive and test the general correlation. For a data set containing 423 of these 441 hydrocarbons, the root mean square (rms) and average absolute deviations are 7.7 and 5.7 K, respectively. The estimated flash points for 18 further hydrocarbons containing complex molecular structures have been compared with one of the best available new group additivity methods, which give much lower values of the rms and average absolute deviations.

Keywords: Flash point, Hydrocarbons, Molecular moieties, Additivity methods

The flash point can be defined as the lowest approaches for prediction of the flash points. The first temperature at which the mixture of vapor and air approaches are not widely implemented because they above the surface of the liquid can be ignited. It depend on specialized software, such as Dragon13, and characterizes the flammability of combustible liquids, quantitative structure-property relationships (QSPR). which may be used to asses the fire hazard associated They often need unusual molecular descriptors, which with designing process, transportation and storage are available only through specialized software. The systems of these compounds. Since there are many other disadvantage of these methods is that the important chemicals or new synthesized compounds compounds with similar molecular structure in for which no flash point data are given, predictive training set of the QSPR procedure should be used as methods for evaluating reported values of flash point test set. Prediction of flash point based on structural and estimating the flash points of new substances contributions are advantageous because this approach continue to be of interest. Moreover, the is applicable even when thermodynamic data for measurements of flash points are more difficult for desired organic compounds are not available and there some classes of organic compounds that have toxicity, is no need to use specialized software. capable of detonation upon heating for explosives and 1-6 Due to the importance of flash points of saturated explosion of their vapors with air . and unsaturated hydrocarbons, different approaches Many methods have been developed to predict the have been reported to predict flash points of these flash point of different classes of pure organic 14-23 7 compounds in recent years . Some of these studies compounds . The most predictive methods require were restricted to acyclic, cyclic or simultaneously accurate values of thermodynamic properties relating cyclic and acyclic hydrocarbons14-18. Among these to volatility of the compounds, typically vapor 7-9 approaches, group contribution methods were also pressure, boiling point and enthalpy of vaporization . used to predict flash point of saturated and Reliable methods for estimation of thermodynamic unsaturated hydrocarbons19,20. Group contribution properties related to volatility of solid or liquid methods require large and reliable experimental data organic compounds, e.g., heats of sublimation of 10-12 in order to consider various structural environment energetic compounds, may be useful . Neural effects. Their restrictions are: (i) the effect of networks and methods of estimating properties based specified groups cannot be applied for some organic on structural contributions are two important compounds in which the specific group values have ______not been defined and (ii) the predicted flash points *E-mail: [email protected]; [email protected] may be large for some of hydrocarbons. 270 INDIAN J. ENG. MATER. SCI., AUGUST 2012

It is important to have a reliable simple method for predicted flash point on the basis of the number of predicting flash point of various types of cyclic and carbon and hydrogen atoms. For some hydrocarbons, acyclic hydrocarbons containing alkanes (paraffins), the flash point depends on the number, type, length and alkenes (olefins), alkynes and aromatic hydrocarbons location of branching along the hydrocarbon chain as (arenes). The purpose of this work is to use the largest well as the number of carbon atoms attached to double available experimental data of flash points of various or triple bonds. Equation (1) can be revised by two hydrocarbons in order to introduce a reliable simple correcting functions as increasing (P(+)) and decreasing general correlation. It will be shown that the novel (P(-)) parameters for predicting the flash point: method provides reliable predictions for any hydrocarbons containing different molecular structures FP=FP(0) + 51.12 P(+) – 49.63 P(-) … (2) and geometries. The estimated results of this method for several hydrocarbons with complex molecular The values of two correcting functions P(+) and P(-) structures will be compared with the calculated values have been chosen on the basis of deviations of FP(0) 20 of group additivity method of Rowley and coworkers from the measured values. In Eq. (2), the structural as one of the best available general methods. parameters P(+) and P(-) are equal to zero if the conditions for giving them various values are not met. Results and Discussion The values of P(+) and P(-) can be easily specified on Flash points of different categories of hydrocarbons the basis of some molecular fragments. including cyclic and acyclic paraffins, alkenes and Structural parameter P(+) alkynes as well as aromatics depend on various (i) Cycloalkanes: This parameter can be used only for structural parameters. A carful examination of the large cycloalkanes that have more than six-membered flash point of many hydrocarbons reveals its complex (+) rings for which the value P is equal to 0.4. dependency on the total number of carbon and (ii) Normal alkanes: For normal alkanes with a≥ 14, hydrogen atoms. Experimental data of different (+) the value of P is 0.25. hydrocarbons were taken from the chemical database (iii) Methyl substituted aromatics: This parameter can of the department of chemistry at the University of be applied only to polymethyl aromatics for which Akron (USA)24. This reference collects experimental P(+) is 0.1 n where n is the number of methyl data for many hazardous chemicals from a large CH3 CH3 number of scientific sources. However, the flash point groups attached to aromatic ring. of different classes of hydrocarbons with general Structural moieties affecting P(-) formula CaHb on the basis of the experimental data given in Table 1 can be expressed as follows: (i) Small cycloalkanes: For cycloalkanes with three- or four-membered rings without any substituent or (0) with the attachment of only methyl groups, the value FP =158.7+19.86a – 2.40b … (1) (-) of P is 0.2. where FP(0) is the main function that has the major (ii) Small acyclic hydrocarbons: If a≤ 5, then P(-)=1.40 contribution to the predicted flash point. A multiple – (a–1.3)×0.35. linear regression method was used to derive Eq. (1) in (iii) The attachment of isopropyl and t-butyl to which its coefficient of determination or the R2- benzene ring: The values of P(-) are 0.85 and 1.5 for value25 is equal to 0.94. As seen in Eq. (1), increasing the attachment of more than two isopropyl or t-butyl the ratio of a/b can increase the flash point of a directly to aromatic ring, respectively. desired hydrocarbon. For example, the measured flash (iv) The attachment of normal alkyl group to benzene point of methylcyclohexane and toluene are 269 and ring: The values of P(-) are 0.5 and 1.0 for the 280 K, respectively. For some compounds belong to attachment of large normal alkyl group with C10 to various categories of hydrocarbons, deviations of C12 and greater than C12, respectively. predicted results from experimental values are large (v) Alkynes with the general formula R-C≡C-H: The and Eq. (1) requires correcting functions. In addition value of P(-) equals − 18.016.1 a where a≤ 6. (-) to elemental composition, the flash point of (vi) Alkenes with formula R1-C=C-R2: P is equal to hydrocarbons is a function of the presence of some 1.55 – 0.25a where a≤ 4. specific molecular structure fragments. Some (vii) The existence of two double bonds: For the molecular moieties can increase or decrease the compounds with formula R1-C=C-C=C-R2 and R1- KESHAVARZ: SATURATED AND UNSATURATED HYDROCARBONS 271

(-) C=C=C-R2, the values of P are 1.75-0.3a and 0.95- the new method provides the simplest and 0.1a, respectively, for which only one of alkyl groups quick pathway for reliable perdition of (R1 or R2) should be methyl group and the other different classes of hydrocarbons. hydrogen atom. The calculated flash points of different categories Different behaviour of mono-alkyl substituted cyclopentane hydrocarbons compounds are given in Table 1 and and cyclohexane (+) (-) compared with corresponding experimental data. Both P or P can be participated for prediction of Since the measured data from different authors as flash point of mono-alkyl substituted cyclopentane well as organizations can differ by as much as 30 K, and cyclohexane, which depend on the number of the reliability of the present method is very good.15 As carbon atoms in alkyl group. For the presence of (+) seen in Table 1, the root mean square (rms) and C1-C2 and C3-C9 in alkyl group, the values of P are average absolute deviations of the predicted results of 0.1 and 0.2, respectively. Meanwhile, the value of P(-) > > the new model are 7.7 and 5.7 K, respectively. Of is (C12 -10)×0.05+0.05, where C12 shows that the 423 unsaturated hydrocarbons given in Table 1, only number of carbon atoms in alkyl group is greater than 1.89% of the estimated flash points are greater than twelve. ±20 K of the measured flash points with maximum The coefficient of determination of Eq. (2) is good, deviation 28 K. The predicted results of the new which is equal to 0.99. Eq. (2) reveals some important model show that it can be easily applied to complex features of safety for saturated and unsaturated molecular structures of hydrocarbons. The predicted hydrocarbons: results of the new model show that it can be easily (i) Hydrocarbons with P(+) values have higher applied to complex molecular structures of flash points with respect to corresponding hydrocarbons. As seen in Table 1, deviations for isomers. Hence, these compounds are safer in several hydrocarbons are greater than ±20 K, which handling. can affect the rms and average absolute deviations (ii) For hydrocarbons with small carbon numbers, appreciably. Since the measured values of flash points the values of P(-) for several conditions of for different isomers of unsaturated hydrocarbons are previous section are large because volatility relatively close to each other, both methods does not of these compounds are high. differentiate between isomers. A visual comparison of (iii) Since there is no need to use correcting the predicted results of the new correlation with the functions P(+) or P(-) for most hydrocarbons, experimental data is also shown in Fig. 1.

Table 1Comparison of the predicted flash points (K) for Table 1 (Contd.)Comparison of the predicted flash points (K) 423 different acyclic alkanes, cyclic alkanes, unsaturated for 423 different acyclic alkanes, cyclic alkanes, unsaturated 24 hydrocarbons and aromatic with experimental data hydrocarbons and aromatic with experimental data24

No. Compound Experi- Pre- Devi- No. Compound Experi- Pre- Devi- mental dicted ation mental dicted ation flash flash flash flash point point point point

1 Methane 85 94 9 12 3-Methylpentane 233 244 11 2 Ethane 138 127 -11 13 Heptane 269 259 -10 3 Propane 169 159 -10 14 3,3-Dimethylpentane 254 259 5 4 Butane 202 192 -11 15 2,4-Dimethylpentane 261 259 -2 5 Pentane 224 224 0 16 3-Ethylpentane 255 259 4 6 2,2-Dimethylpropane 208 224 16 17 2,2-Dimethylpentane 250 259 9 7 2-Methylbutane 216 224 8 18 2,3-Dimethylpentane 266 259 -7 8 Hexane 250 244 -6 9 2,2-Dimethylbutane 225 244 19 19 2-Methylhexane- 269 259 -10 10 2,3-Dimethylbutane 244 244 0 20 3-Methylhexane 258 259 1 11 2-Methylpentane 250 244 -6 21 2,2,3-Trimethylbutane 247 259 12

(Contd.) (Contd.) 272 INDIAN J. ENG. MATER. SCI., AUGUST 2012

Table 1 (Contd.)Comparison of the predicted flash points (K) Table 1 (Contd.)Comparison of the predicted flash points (K) for 423 different acyclic alkanes, cyclic alkanes, unsaturated for 423 different acyclic alkanes, cyclic alkanes, unsaturated hydrocarbons and aromatic with experimental data24 hydrocarbons and aromatic with experimental data24

No. Compound Experi- Pre- Devi- No. Compound Experi- Pre- Devi- mental dicted ation mental dicted ation flash flash flash flash point point point point

22 Octane 286 274 -12 63 3,3-Diethylpentane 294 289 -5 23 2,2,3,3-Tetramethylbutane 273 274 1 64 Tetraethylmethane 294 289 -5 24 2,3,4-Trimethylpentane 273 274 1 65 3-Ethyl-2,2-dimethylpentane 286 289 3 25 3,4-Dimethylhexane 277 274 -3 66 2,4,4-Trimethylhexane 288 289 1 26 2,2,4-Trimethylpentane 261 274 13 67 4,4-Dimethylheptane 288 289 1 27 2,2,3-Trimethylpentane 270 274 4 68 3ethyl-2-methylhexane 288 289 1 28 3-Methyl-3-ethylpentane 276 274 -2 69 3-Ethyl-3-methylhexane 288 289 1 29 3-Ethylhexane 278 274 -4 70 4-Ethyl-2-methylhexane 288 289 1 30 3-Methylheptane 279 274 -5 71 3-Ethyl-4-Methylhexane 288 289 1 31 3,3-Dimethylhexane 272 274 2 72 2,4-Dimethyl-3-ethylpentane 288 289 1 32 2,3-Dimethylhexane 283 274 -9 73 2,2,4-Trimethylhexane 288 289 1 33 2,4-Dimethylhexane 283 274 -9 74 2,3,3-Trimethylhexane 288 289 1 34 2,5-Dimethylhexane 271 274 3 75 Decane 319 305 -15 35 2,3,3-Trimethylpentane 273 274 1 76 3-Ethyloctane 314 305 -10 36 2-Methylheptane 278 274 -3 77 4-Ethyloctane 314 305 -10 78 2,2,4-Trimethylheptane 304 305 0 37 2,2-Dimethylhexane 269 274 5 79 3,4,4-Trimethylheptane 304 305 0 38 4-Methylheptane 278 274 -4 80 3,3,4-Trimethylheptane 304 305 0 39 3-Ethyl-2-methylpentane 276 274 -2 81 2,4,4-Trimethylheptane 304 305 0 40 Nonane 304 289 -15 82 2,3,6-Trimethylheptane 304 305 0 41 2,5-Dimethylheptane 288 289 1 83 2,3,5-Trimethylheptane 304 305 0 42 3,3-Dimethylheptane 300 289 -11 84 2,3,3-Trimethylheptane 304 305 0 43 3,4-Dimethylheptane 288 289 1 85 2,2,5-Trimethylheptane 304 305 0 44 2,3-Dimethylheptane 288 289 1 86 2,2,6-Trimethylheptane 304 305 0 45 2,6-Dimethylheptane 299 289 -10 87 2,4,5-Trimethylheptane 304 305 0 46 2,3-Dimethyl-3-ethylpentane 288 289 1 88 2,5-Dimethyloctane 314 305 -10 47 2,2,5-Trimethylhexane 286 289 3 89 2,4-Dimethyloctane 314 305 -10 48 4-Methyloctane 295 289 -6 90 4,4-Dimethyloctane 314 305 -10 49 2-Methyloctane 297 289 -8 91 4,5-Dimethyloctane 314 305 -10 50 3-Methyloctane 297 289 -8 92 3,4-Dimethyloctane 314 305 -10 51 2,2,3,4-Tetramethylpentane 284 289 5 93 3,6-Dimethyloctane 314 305 -10 52 2,3,3,4-Tetramethylpentane 284 289 5 94 2,3-Dimethyloctane 314 305 -10 53 2,2,4,4-Tetramethylpentane 276 289 13 95 3,3-Diethylhexane 311 305 -7 54 3-Ethylheptane 295 289 -6 96 3,3-Dimethyloctane 314 305 -10 55 4-Ethylheptane 288 289 1 97 3,5-Dimethyloctane 314 305 -10 56 2,2-Dimethylheptane 297 289 -8 98 2,6-Dimethyloctane 314 305 -10 57 2,4-Dimethylheptane 288 289 1 99 3-Ethyl-2,2-dimethylhexane 311 305 -7 58 2,3,4-Trimethylhexane 288 289 1 100 3,3,4,4-Tetramethylhexane 304 305 0 59 3,3,4-Trimethylhexane 288 289 1 101 2,2,5,5-Tetramethylhexane 304 305 0 60 2,3,5-Trimethylhexane 288 289 1 102 2,2,3,5-Tetramethylhexane 304 305 0 61 2,2,3-Trimethylhexane 288 289 1 103 2,3,3,4-Tetramethylhexane 304 305 0 62 3,5-Dimethylheptane 288 289 1 104 2,3,3,5-Tetramethylhexane 304 305 0

(Contd.) (Contd.) KESHAVARZ: SATURATED AND UNSATURATED HYDROCARBONS 273

No. Compound Experi- Pre- Devi- No. Compound Experi- Pre- Devi- mental dicted ation mental dicted ation flash flash flash flash point point point point

105 2,2,4,5-Tetramethylhexane 304 305 0 147 trans-1,3-Dimethylcyclopentane 260 264 4 106 2,3,4,5-Tetramethylhexane 304 305 0 148 Cyclooctane 303 300 -3 107 2,2,4,4-Tetramethylhexane 304 305 0 149 Ethylcyclohexane 292 284 -8 108 3,3,5-Trimethylheptane 304 305 0 150 Isopropylcyclopentane 287 289 2 109 2,3,5-Trimethylheptane 304 305 0 151 n-Propylcyclopentane 289 289 0 110 3-Ethyl-3-Methylheptan 314 305 -10 152 1,1-Dmethylcyclohexane 276 279 3 111 5-Ethyl-2-Methylheptan 314 305 -10 153 1-Ethyl-1-methylcyclopentane 279 279 0 112 3-Ethyl-4-Methylheptan 304 305 0 154 1,2-Dmethylcyclohexane 288 279 -9 113 4-Ethyl-3-Methylheptan 314 305 -10 155 Cis-1,2-Dmethylcyclohexane 295 279 -16 114 4-Methylnonane 311 305 -7 156 trans-1,2-Dmethylcyclohexane 290 279 -11 115 3-Methylnonane 314 305 -10 157 1,3-Dmethylcyclohexane 279 279 0 116 2-Methylnonane 314 305 -10 158 Cis-1,3-Dmethylcyclohexane 279 279 0 117 2,4,6-Trimethylheptane 304 305 0 159 Trans-1,3-Dmethylcyclohexane 281 279 -2 118 3-Ethyl-2,3,4-Trimethylpentane 304 305 0 160 Cyclononane 316 315 -1 119 2,3,4,4-Tetramethylhexane 304 305 0 161 Isopropylcyclohexane 308 305 -4 120 3,4,5-Trimethylheptane 304 305 0 162 Butylcyclopentane 308 305 -4 121 3-Ethyl-5-methylheptane 304 305 0 163 Propylcyclohexane 304 305 0 122 5-Methylnonane 312 305 -8 164 Cyclodecane 338 330 -8 123 2,2,3,4-Tetramethylhexane 304 305 0 165 n-Butylcyclohexane 314 320 5 124 4-Propylheptane 314 305 -10 166 Pentylcyclopentane 324 320 -5 125 Undecane 333 320 -14 167 Hexylcyclopentane 339 335 -5 126 Dodecane 344 335 -9 168 Pentylcyclohexane 339 335 -5 127 Tridecane 352 350 -2 169 Cyclododecane 371 360 -11 128 Tetradecane 372 378 5 170 1-Cyclohexylhexane 353 350 -3 129 Hexadecane 408 408 0 171 Heptylcyclopentane 352 350 -2 130 Heptadecane 421 423 2 172 1-Cyclohexylheptane 366 365 -1 131 Octadecane 438 438 0 173 Octylcyclopentane 365 365 0 132 Cyclobutane 206 209 3 174 Cyclohexyloctane 378 380 2 133 Cyclopentane 231 234 3 175 Cyclohexylnonane 390 395 5 134 trans1,2-Dimethylcyclopropane 219 224 5 176 Cyclopentylundecane 399 400 1 135 Methylcyclobutane 227 224 -3 177 Cyclohexyldecane 404 400 -4 136 Ethylcyclopropane 231 234 3 178 Undecylcyclohexane 411 415 4 137 Cyclohexane 255 249 -6 179 Cyclopentyldodecane 409 407 -2 138 Ethylcyclobutane 250 249 -1 180 Cyclohexyldodecane 420 420 0 139 cis-1-Ethyl-2-methylcyclopropane 244 249 5 181 Cyclopentyltridecane 418 417 -1 140 1-Ethyl-1-methylcyclopropane 240 249 9 182 Cyclohexyltridecane 429 430 1 141 Cycloheptane 279 285 5 183 Cyclopentyltetradecane 427 428 1 142 Methylcyclohexane 269 269 0 184 Benzene 262 263 1 143 Ethylcyclopentane 269 269 0 185 Toluene 280 284 4 144 trans-1,2-Dimethylcyclopentane 263 264 1 186 Ethylbenzene 288 294 6 145 Cis-1,2-Dimethylcyclopentane 269 264 -5 187 P-Xylene 300 304 4 146 Cis-1,3-Dimethylcyclopentane 259 264 5 188 O-Xylene 303 304 1

(Contd.) (Contd.) 274 INDIAN J. ENG. MATER. SCI., AUGUST 2012

No. Compound Experi- Pre- Devi- No. Compound Experi- Pre- Devi- mental dicted ation mental dicted ation flash flash flash flash point point point point

189 Propylbenzene 303 309 6 231 1,3,5-Triisopropylbenzene 359 357 -2 190 Cumene 304 309 5 232 Decylbenzene 380 389 9 191 m-Ethyltoluene 311 309 -2 233 Pentaethylbenzene 386 414 28 192 1,2,3-Trimethylbenzene 324 324 0 234 n-Undecylbenzene 409 404 -5 193 1,2,4-Trimethylbenzene 321 324 3 235 Dodecylbenzene 418 419 1 194 1,3,5-Trimethylbenzene 317 324 7 236 1,2,4,5-Teraisopropylbenzene 397 402 5 195 o-Ethyltoluene 312 309 -3 237 1,3,5-Tri-tert-butylbenzene 372 370 -2 196 p-Ethyltoluene 309 309 0 238 Tridecylbenzene 385 410 25 197 Naphthalene 360 338 -22 239 1-Methylanthracene 430 433 3 198 Butylbenzene 331 324 -7 240 2-Methylanthracene 431 433 2 199 1,2,4,5-Tetramethylbenzene 346 344 -2 241 9-Methylanthracene 431 433 2 200 2-Ethyl-p-xylene 329 324 -5 242 1-methylphenathrene 431 433 2 201 3-Ethyl-o-xylene 338 324 -14 243 Retene 451 473 22 202 4-Ethyl-m-xylene 330 324 -6 244 Phenylacetylene 303 303 0 203 tert-Butylbenzene 307 324 17 245 Styrene 304 298 -6 204 P-Cymene 320 324 4 246 2-Vinyltoluene 320 313 -7 205 o-DiEthylbenzene 322 324 2 247 3-vinyltoluene 324 313 -11 206 m-DiEthylbenzene 324 324 0 248 Allylbenzene 310 313 3 207 p-DiEthylbenzene 328 324 -4 249 beta-Methylstyrene 333 313 -20 208 4-Ethyl-1,2-dimethylbenzene 331 324 -7 250 cis-1-Propenylbenzene 325 313 -12 209 1-methylnaphtalene 355 358 3 251 Isopropenylbenzene 313 313 0 210 n-Pentylbenzene 339 339 0 252 trans-1-phenyl-1-propene 331 313 -18 211 IsoPentylbenzene 335 339 4 253 m-Divinylbenzene 338 333 -5 212 Pentamethylbenzene 364 364 0 254 p-Divinylbenzene 337 333 -4 213 p-tert-Butyltoluene 321 339 18 255 1-Butynylbenzene 341 333 -8 214 2-Phenyl-2methylbutane 338 339 1 256 3-Ethylstyrene 333 329 -4 215 1-Ethylnaphtalene 380 368 -12 257 4-Ethylstyrene 335 329 -6 216 2-Ethylnaphtalene 377 368 -9 258 2,4-Dimethylstyrene 333 329 -4 217 1,3-Dimethylnaphtalene 382 379 -3 259 Acetylene 155 154 -1 218 1,2-Dimethylnaphtalene 374 379 5 260 Propyne 186 178 -8 219 Hexylbenzene 356 354 -2 261 1-Pentyne 230 239 9 220 Hexamethylbenzene 377 385 8 262 2-Pentyne 253 239 -14 221 3,5-Dimethyl-tert-butylbenzene 357 354 -3 263 3-Methyl-1-butyne 221 221 0 222 1,2,4-Trimethylbenzene 349 354 5 264 1-Hexyne 252 250 -2 223 1,3,5-Trimethylbenzene 354 354 0 265 2-Hexyne 263 254 -9 224 1,4-Diisopropylbenzene 354 354 0 266 3-Hexyne 259 254 -5 225 m-Diisopropylbenzene 350 354 4 267 3,3-Dimethyl-1-butyne 239 250 11 226 n-Heptylbenzene 368 369 1 268 4-Methyl-1-Pentyne 249 250 1 227 1,2,3,4-Tetraethylbenzene 367 384 17 269 1,6-Heptadiyne 282 279 -3 228 2-Phenyloctane 373 384 11 270 1-Heptyne 263 269 6 229 n-Octylbenzene 380 384 4 271 2-Heptyne 275 269 -6 230 n-Nonylbenzene 390 399 9 272 3-Heptyne 257 269 12

(Contd.) (Contd.) KESHAVARZ: SATURATED AND UNSATURATED HYDROCARBONS 275

No. Compound Experi- Pre- Devi- No. Compound Experi- Pre- Devi- mental dicted ation mental dicted ation flash flash flash flash point point point point

273 3-Methyl-1-hexyne 268 269 1 315 3-Methyl-1,4-Pentadiene 239 254 15 274 1,7-Octadiyne 296 294 -2 316 2-Methyl-2,3-Pentadiene 255 254 -1 275 2,6-Octadiene 307 294 -13 317 1-Hexene 253 249 -4 276 1-Octyne 289 284 -5 318 Cis-2-Hexene 252 249 -3 277 2-Octyne 301 284 -17 319 Cis-3-Hexene 261 249 -12 278 4-Octyne 291 284 -7 320 trans-3-Hexene 261 249 -12 279 1,8-Nonadiyne 314 309 -5 321 Isohexene 241 249 8 280 1-Nonyne 306 299 -7 322 2,3-Dimethyl-1-butene 255 249 -6 281 1-Decyne 323 314 -9 323 2,3-Dimethyl-2-butene 256 249 -7 282 1-Undecyne 338 329 -9 324 3,3-Dimethyl-1-butene 244 249 5 283 4-Undecyne 341 329 -12 325 2-Methyl-1-penene 241 249 8 284 1-Dodecyne 352 344 -8 326 2-Methyl-2-pentene 246 249 3 285 1-Tridecyne 366 359 -7 327 4-Methyl-2-pentene 241 249 8 286 Cyclobutene 202 224 22 328 3-Methyl-1-pentene 244 249 5 287 Cyclopentene 244 239 -5 329 trans-3-Methyl-2-pentene 266 249 -17 288 Cyclohexene 256 254 -2 330 2-Ethyl-1-butene 243 249 6 289 4-Methylcyclopentene 243 254 11 331 1,6-Heptadiene 263 269 6 290 Cycloheptene 267 269 2 332 1-Heptene 264 264 0 291 4-Methylcyclohexene 272 269 -3 333 Cis-2-Heptene 265 264 -1 292 3-Methylcyclohexene 270 269 -1 334 trans-2-Heptene 267 264 -3 293 4-Ethylcyclohexene 286 284 -2 335 trans-3-Heptene 266 264 -2 294 Ethylene 137 137 0 336 2-Methyl-1-hexene 267 264 -3 295 Propene 165 164 -1 337 4-Methyl-1-hexene 258 264 6 296 Propadiene 177 176 -1 338 2-Ethyl-1-pentene 263 264 1 297 1,2-Butadiene 197 196 -1 339 2,4-Dimethyl-2-pentene 264 264 0 298 1,3-Butadiene 197 196 -1 340 2,3,3-Trimethyl-1butene 256 264 8 299 Butene 194 192 -2 341 Cis-5-Methyl-2-Hexene 268 264 -4 300 Cis-2-Butene 200 192 -8 342 trans-5-Methyl-2-Hexene 268 264 -4 301 Isobutylene 197 192 -5 343 trans-3-Octene 282 279 -3 302 1,2-Pentadiene 233 239 6 344 trans-4-Octene 281 279 -2 303 2,3-Pentadiene 235 239 4 345 Cis-4-Octene 294 279 -15 304 cis-1,3-pentadiene 232 226 -6 346 1,8-Nonadiene 299 299 0 305 2-methylbutadiene 225 226 1 347 2-Ethyl-1-hexene 279 279 0 306 Pentene 229 234 5 348 1-Nonene 298 294 -4 307 2-Pentene 253 234 -19 349 1-Undecene 336 324 -12 308 Cis-2-Pentene 227 234 7 350 Dodecane 351 339 -12 309 Trans-2-Pentene 225 234 9 351 2-Methyl-1-undecene 345 339 -6 310 Isopentene 211 234 23 352 1-Tridecene 352 355 3 311 1,4,-Hexadiene 248 254 6 353 1-Tetradecene 383 370 -13 312 2,4-Hexadiene 264 254 -10 354 1-Pentadecene 386 385 -1 313 1,5-Hexadiene 246 254 8 355 1-Hexadecene 402 400 -2 314 2,3-Dimethyl-1,3-butadiene 251 254 3 356 1-Heptadecene 408 415 7

(Contd.) (Contd.) 276 INDIAN J. ENG. MATER. SCI., AUGUST 2012

No. Compound Experi- Pre- Devi- No. Compound Experi- Pre- Devi- mental dicted ation mental dicted ation flash flash flash flash point point point point

357 sec-Butylbenzene 318 324 6 391 2-Methyl-2-hexene 269 264 -5 358 IsoButylbenzene 323 324 1 392 3-Methyl-1-hexene 267 264 -3 359 1,2,3,4-Tetramethylbenzene 341 344 3 393 2-Hexene 253 249 -4 360 1,2,3,5-Tetramethylbenzene 336 344 8 394 trans-2-Hexene 246 249 3 361 Neopentylbenzene 323 339 16 395 3-Ethyl-1-pentene 256 264 8 362 M-Cymene 323 324 1 396 3-Ethyl-2-pentene 267 264 -3 363 2-methylnaphtalene 371 358 -13 397 1,3-Pentadiene 244 239 -5 364 3,4-Dimethylcumene 341 339 -2 398 Tetradecyne 378 374 -4 365 1,4-Dimethylnaphtalene 383 379 -4 399 1-Pentadecyne 390 389 -1 366 2,3-Dimethylnaphtalene 387 379 -8 400 1-Hexadecyne 401 405 4 367 1,4-Di-tert-butylbenzene 370 384 14 401 1-Octadecyne 422 435 13 368 Diisopropylbenzene 344 354 10 402 p-Methylisopropenylbenzene 332 329 -3 369 9,10-Dimethylanthracene 442 453 11 403 9-Vinylanthracene 445 448 3 370 4-vinyltoluene 318 313 -5 404 1,5-Dimethylnaphtalene 384 379 -5 371 cis-(1-Methyl-1-propenyl)benzene 328 329 1 405 1,6-Dimethylnaphtalene 383 379 -4 372 1-Pentynylbenzene 355 348 -7 406 2,7-Dimethylnaphtalene 382 379 -3 373 1-Vinylnaphthalene 389 373 -16 407 2,6-Dimethylnaphtalene 382 379 -3 374 1-Butyne 207 224 17 408 1-Phenylnaphthalene 435 448 13 375 5-Methyl-1-hexyne 269 269 0 409 4,4-DiMethyl-2-Pentyne 263 254 -9 376 1-Nonadeyne 431 450 19 410 6-Methyl-2-heptyne 295 284 -11 377 Cyclooctene 298 284 -14 411 6-Methyl-3-heptyne 289 284 -5 378 Trans-2-Butene 200 219 19 412 1-Methylcyclopentene 256 254 -2 379 2-Methyl-1-butene 226 234 8 413 1-Methylcyclohexene 269 269 0 380 3-Methyl-1,3-Pentadiene 244 254 10 414 1,3-Dimethylcyclohexene 285 284 -1 381 1,9-Decadiene 314 314 0 415 3-Menthene 316 314 -2 382 1-Decene 322 309 -13 416 2,4-Dimethyl-1,3-Pentadiene 283 269 -14 383 trans-5-Decene 319 309 -10 417 2,5-Dimethyl-1,5-hexadiene 286 284 -2 384 1,7-Octadiene 278 284 6 418 2,5-Dimethyl-2,4-hexadiene 302 284 -18 385 1-Octadecene 421 430 9 419 2,4,4-Trimethyl-2-Pentane 268 279 11 386 1-Nonadecene 430 445 15 420 2,4,4-Trimethylpentane 256 279 23 387 1-Eicosene 439 460 21 421 trans-1,2-di-tert-butylethylene 306 309 3 388 1-Octene 281 279 -2 422 3,7-Dimethyl-1-octene 317 309 -8 389 trans-2-Octene 287 279 -8 423 3-Methyl-1,2-butadiene 230 239 9 390 2-Methyl-1,3-Pentadiene 255 254 -1 The rms deviation 7.7 (Contd.) The average absolute deviation 5.7

Among different approaches for prediction of flash be used for some hydrocarbons22. Rowley and coworkers point of hydrocarbons, group contribution method is a have recently introduced a general method with fourteen suitable approach for prediction of flash points of group contribution values, which can be used for different classes of hydrocarbons. Since group additivity prediction of flash point of different hydrocarbons20. Their methods require the values of different types of structural method cannot also be used for those hydrocarbons with – groups, these methods such as Albahri’s method19 cannot C=C=C- structural parameter.

KESHAVARZ: SATURATED AND UNSATURATED HYDROCARBONS 277

Table 2 shows a comparison of the predicted results new method is surprisingly very good as compared to by the new and Rowley et al.20 methods for 18 one of the best available methods, i.e., Rowley et al.20 hydrocarbons with complex molecular structures that method. As seen in Table 2, both the rms and average have not been used in Table 1. For nine compounds absolute deviations of new model are much lower than given in Table 2, correcting functions P(+) and P(-) were Rowley et al.20 method. A visual comparison of the used where deviations of FP(0) from experimental data predictions of the methods of new and Rowley et al.20 are large. As indicated in Table 2, the reliability of the methods with experiment is also given in Fig. 2.

Fig. 2 Calculated flash points versus experimental data for different Fig. 1 Calculated flash points versus measured data for different 18 hydrocarbons with complex molecular structures given in Table 2. 423 saturated and unsaturated hydrocarbons given in Table 1. The The solid lines represent exact agreement between predictions and solid lines represent exact agreement between predictions and experiment. Filled and hollow circles denote calculated results of the experiment. new and Rowley et al.20 methods, respectively.

Table 2Comparison of the predicted flash points of the new model as well as group contribution method Rowley et al.20 with experimental data24 for some hydrocarbons containing complex molecular structure

No. Compound Experimental flash point New model Deviation Rowley et al. Deviation 1 2,2,3,3- Tetramethylpentane 289 289 0 276 -14 2 Pentadecane 405 393 -12 389 -16 3 Methylcyclopropane 194 209 15 234 40 4 Methylcyclopentane 256 254 -2 239 -17 5 1,1,4,-Trimethylcycloheptane 316 330 14 284 -32 6 tert-Butylcyclohexane 313 320 6 306 -7 7 Nonylcyclopentane 377 380 3 383 6 8 Cyclotetradecane 386 390 4 336 -50 9 Cyclohexyltetradecane 438 440 2 460 22 10 Tetradecylbenzene 433 425 -8 468 35 11 1-Eicosyne 440 465 25 463 23 12 Cyclododecene 367 344 -23 319 -49 13 2-Methyl-2-butene 266 234 -32 237 -29 14 2-Methyl-1,4-Pentadiene 271 254 -17 248 -23 15 1,4-Pentadiene 277 239 -38 227 -50 16 2-Phenylnaphthalene 428 448 20 448 20 17 1-Methylcyclobutene 228 239 11 254 26 18 1,5,5-Trimethylcyclohexene 295 299 4 261 -34

The rms deviation 16.5 30.5 The average absolute deviation 13.1 27.4 278 INDIAN J. ENG. MATER. SCI., AUGUST 2012

Conclusions 4 Keshavarz M H, High Temp-High Press, 35/36 (2003/2006) A reliable simple method has been introduced to 587-592. 5 Keshavarz M H, Ramadan A, Mousaviazar A, Zali A, predict the flash points of different classes of Esmailpour K, Atabaki F & Shokrollahi A, J Energ Mater saturated and unsaturated hydrocarbons containing ,29 (2011) 46-60. cyclic and acyclic paraffins, alkenes and alkynes as 6 Keshavarz M H, Ramadan A, Mousaviazar A, Zali A & well as aromatics. The FP(0) has the major Shokrollahi A, J Energ Mater 29 (2011) 228-240. contribution to the predicted flash point, which can be 7 Rowley J R, Freeman, D K, Rowley, R L, Oscarson, J L, Giles N F & Wilding W V, Int J Thermophys, 31 (2010) 875-887. revised by two correcting functions. The values of 8 Liu X & Liu Z, J Chem Eng Data, 55 (2010) 2943-2950. (+) (-) two correcting functions P and P depend on the 9 Gharagheizi F, Keshavarz M H & Sattari M, J Therm Anal presence of some molecular moieties that may revise Calorim DOI 10.1007/s10973-011-1951-5 (on line FP(0) according to Eq. (2). The present method has publication). 10 Keshavarz M H, J Hazard Mater, 151 (2008) 499-506. been tested for 441 different saturated and unsaturated 20 11 Keshavarz M H & Yousefi M H, J Hazard Mater, 152 hydrocarbons. As compared to Rowley et al. (2008) 929-933. method, the present method provides more reliable 12 Keshavarz M H, J Hazard Mater, 177 (2010) 648-659. results for different hydrocarbons containing complex 13 Talete S R L, Dragon for windows (Software for molecular molecular structures. Thus, the new model can be Descriptor Calculations), Version 5.4, 2006 (http://www/talete.mi.it/). easily applied for different types of saturated and 14 Vazhev V V, Aldabergenov M K & Vazheva N V, Petrol unsaturated hydrocarbons regardless of complexity of Chem, 46 (2006) 136-139. their molecular structures. 15 Pan Y, Jiang J & Wang Z, J Hazard Mater, 147 (2007) 424-430. 16 Mathieu D, J Hazard Mater, 179 (2010) 1161-1164. 17 Carroll F A, Lin C & Quina F H, Energ Fuel, 24 (2010) Acknowledgement 392-395. I would like to thank the research committee of 18 Carroll F A, Lin C & Quina F H, Energ Fuel, 24 (2010) Malek-ashtar University of Technology (MUT) for 4854-4856. supporting this work. 19 Albahri T, Chem Eng Sci, 58 (2003) 3629-3641. 20 Rowley J R, Rowley R L & Wilding W V, Process Saf Prog, 29 (2010) 353-358. References 21 Keshavarz M H, Motamedoshariati H & Ghanbarzadeh M, 1 Pouretedal H R & Keshavarz M H, J Iran Chem Soc, 8 Khimiya, 20 (2011) 58-75. (2011) 78-89. 22 Keshavarz M H & Ghanbarzadeh M, J Hazard Mater, 193 2 Keshavarz M H, in Hazardous Materials: Types, Risks and (2011) 335– 341. Control, edited by S K Brar, (Nova Science Publishers, Inc), 23 Saldana D A, Starck L, Mougin P, Rousseau B, Pidol L, 2011. Jeuland N & Creton B, Energy Fuel, 25 (2011) 3900-3908. 3 Agrawal J P, High energy materials: propellants, explosives 24 http://ull.chemistry.uakron.edu/erd/index.html. and pyrotechnics (Wiley-VCH Verlag GmbH & Co. KGaA, 25 Palm III W J, Introduction to matlab for engineers, Weinheim), 2010. (McGraw-Hill, New York), 2005.