Joback method

The Joback method (often also referred to as the Joback-Reid method ) allows the prediction of eleven important thermodynamic properties of pure substances exclusively from the molecular structure.

Basics

Group contribution method

Principle of a group contribution method

The Joback method is a group contribution method . This type of prediction method takes simple structural information of a chemical molecule, such as a list of functional groups , assigns parameters to those groups, and calculates thermophysical and transport properties as a function of the sum of these group parameters.

Joback assumed that there were no interactions between the groups and therefore only used additive group contributions and no contributions for intergroup interactions. Other methods, such as UNIFAC , which estimates mixture properties such as activity coefficients, or the Benson method , which estimates heat capacities, enthalpies and entropies of formation, also use interaction parameters in addition to the simple, purely additive contributions. The great advantage of the restriction to simple contributions is the small number of parameters required (one parameter for each group and property), while the number of interaction parameters increases sharply with increasing number of groups (1 for two groups, 3 for three, 6 for four, 45 for ten, and even twice as much if the interaction parameters are not symmetrical).

Nine of the properties predicted by the Joback model are temperature-independent quantities; most of them are simply calculated from the sum of the group contributions plus a summand.

Two of the properties are temperature-dependent: the ideal gas heat capacity and the dynamic viscosity of liquids. A cubic polynomial with four parameters is used for the heat capacity and a polynomial with only two parameters (straight line) for the liquid viscosity. In both cases, the equation parameters are determined from group amounts.

history

The Joback method is an extension of the Lydersen method and uses very similar groups, formulas and parameters for the properties that Lydersen already supported (critical temperature, critical pressure and critical volume).

Joback extended the model for further properties, certain new parameters and slightly modified the equations of the old Lydersen model.

Model strengths and weaknesses

Strengthen

The popularity of the Joback method derives essentially from the one group list that is the same for all properties. This allows all eleven supported properties to be predicted from a single analysis of a chemical structural formula.

In addition, the groups of the Joback model are kept very simple and can also be used with little chemical knowledge.

weaknesses

Systematic error of the Joback method (normal boiling point)

Recent developments in estimation methods have shown that the quality of the Joback method is limited. The original authors have already stated in their publication: “ High accuracy is not claimed, but the proposed methods are often as or more accurate than techniques in common use today .” (German for example: “High accuracy is not claimed, but they are proposed methods are often as precise or more precise than currently used methods. ")

The list of groups does not sufficiently cover many common components. In particular, aromatic substances are not differentiated from normal ring components. This is a serious problem because the properties of these classes of components differ significantly.

The database that Joback and Reid used to determine the group parameters was quite small and only covered a small number of different substances. The best database was achieved for normal boiling points (438 components) and the worst for the enthalpy of fusion (155 components). In addition, it is very difficult to predict the enthalpy of fusion using group contribution methods. Joback and Reid themselves therefore write that the accuracy of the estimation of the enthalpy of fusion is only very low. Current model developments have a much larger database due to the use of fact databases such as the Dortmund database or the DIPPR database.

The formula used to predict the normal boiling point shows another problem. Joback assumed that the contribution of groups in a homologous series like that of the alkanes remains constant. However, this is not a correct assumption. Instead of constant contributions, a decrease in contributions as the number of groups increases must be used. The formula that Joback selected leads to high deviations for small and large molecules and provides an acceptable estimate only for medium-sized components.

Formulas

In the following formulas denotes a group contribution. are added for each individual occurrence of a group. So if a group occurs three times, for example, its contribution is added three times. ${\displaystyle G_{\text{i}}}$ ${\displaystyle G_{\text{i}}}$

size	formula	comment
Normal boiling point	${\displaystyle T_{\text{b}}=198{,}2+\sum {G_{\text{i}}}}$
Melting point	${\displaystyle T_{\text{m}}=122{,}5+\sum {G_{\text{i}}}}$
Critical temperature	${\displaystyle T_{\text{c}}=T_{\text{b}}\left[0{,}584+0{,}965\sum {G_{\text{i}}}-\left(\sum {G_{\text{i}}}\right)^{2}\right]^{-1}}$	This equation requires a normal boiling point T b . If an experimental value is available, it is recommended that you use it. On the other hand, it is also possible to use a value estimated with the Joback method. However, this leads to a bigger error.
Critical pressure	${\displaystyle P_{\text{c}}=\left[{0{,}113+0{,}0032\cdot N_{\text{A}}-\sum {G_{\text{i}}}}\right]^{-2}}$	${\displaystyle N_{\text{A}}}$: Number of atoms in the molecular structure (including hydrogen)
Critical volume	${\displaystyle V_{\text{c}}=17{,}5+\sum {G_{\text{i}}}}$
Enthalpy of formation	${\displaystyle H_{\text{f}}=68{,}29+\sum {G_{\text{i}}}}$	Ideal gas, 298 K
Gibbs energy of formation	${\displaystyle G_{\text{f}}=53{,}88+\sum {G_{\text{i}}}}$	Ideal gas, 298 K
Heat capacity	${\displaystyle {\begin{aligned}C_{\text{P}}=&\sum a_{\text{i}}-37{,}93\\&+\left[\sum b_{\text{i}}+0{,}210\right]T\\&+\left[\sum c_{\text{i}}-3{,}91\cdot 10^{-4}\right]T^{2}\\&+\left[\sum d_{\text{i}}+2{,}06\cdot 10^{-7}\right]T^{3}\end{aligned}}}$	Ideal gas; The Joback method uses a cubic polynomial with four parameters to describe the temperature dependence of the heat capacity of the ideal gas. The parameters are valid in the range from 273 K to 1000 K.
Enthalpy of evaporation at the normal boiling point	${\displaystyle \Delta H_{\text{v}}=15{,}30+\sum G_{\text{i}}}$
Enthalpy of fusion	${\displaystyle \Delta H_{\text{m}}=-0{,}88+\sum G_{\text{i}}}$
Dynamic viscosity of the liquid	${\displaystyle \eta _{\text{L}}=M_{\text{w}}e^{\left[\sum \eta _{\text{A}}-597{,}82\right]/T+\sum \eta _{\text{b}}-11{,}202}}$	${\displaystyle M_{\text{w}}}$: Molar mass ; The Joback method uses two parameters to describe the temperature dependence of the liquid viscosity. The authors state that the parameters are valid up to a reduced temperature . ${\displaystyle T_{\text{r}}<0{,}7}$

Group contributions

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group	T c	P c	V c	T b	T m	H f	G f	a	b	c	d	H m	H v	a	b
	Critical point			Phase transition temperatures		Caloric quantities		Heat capacity ideal gas				Phase transition enthalpies		Dynamic viscosity
Non-ring groups
-CH3	0.0141	−0.0012	65	23.58	−5.10	-76.45	−43.96	1.95e + 1	−8.08E − 3	1.53E − 4	−9.67E − 8	0.908	2.373	548.29	−1.719
–CH 2 -	0.0189	0.0000	56	22.88	11.27	−20.64	8.42	−9.09E − 1	9.50E − 2	−5.44E − 5	1.19E-8	2,590	2.226	94.16	−0.199
> CH–	0.0164	0.0020	41	21.74	12.64	29.89	58.36	−2.30E + 1	2.04E − 1	−2.65E − 4	1.20E − 7	0.749	1.691	−322.15	1.187
> C <	0.0067	0.0043	27	18.25	46.43	82.23	116.02	−6.62E + 1	4.27E − 1	−6.41E − 4	3.01E − 7	−1.460	0.636	−573.56	2.307
= CH 2	0.0113	−0.0028	56	18.18	−4.32	−9.630	3.77	2.36E + 1	−3.81E − 2	1.72E − 4	−1.03E − 7	−0.473	1.724	495.01	−1.539
= CH–	0.0129	−0.0006	46	24.96	8.73	37.97	48.53	−8.00	1.05E − 1	−9.63E − 5	3.56E − 8	2.691	2.205	82.28	−0.242
= C <	0.0117	0.0011	38	24.14	11.14	83.99	92.36	−2.81E + 1	2.08E − 1	−3.06E − 4	1.46E − 7	3.063	2.138	n. v.	n. v.
= C =	0.0026	0.0028	36	26.15	17.78	142.14	136.70	2.74E + 1	−5.57E − 2	1.01E − 4	−5.02E − 8	4,720	2,661	n. v.	n. v.
≡CH	0.0027	−0.0008	46	9.20	−11.18	79.30	77.71	2.45E + 1	−2.71E − 2	1.11E − 4	−6.78E − 8	2,322	1.155	n. v.	n. v.
≡C–	0.0020	0.0016	37	27.38	64.32	115.51	109.82	7.87	2.01E − 2	−8.33E − 6	1.39E-9	4.151	3.302	n. v.	n. v.
Ring groups
–CH 2 -	0.0100	0.0025	48	27.15	7.75	−26.80	−3.68	−6.03	8.54E − 2	−8.00E − 6	−1.80E − 8	0.490	2,398	307.53	−0.798
> CH–	0.0122	0.0004	38	21.78	19.88	8.67	40.99	−2.05E + 1	1.62E − 1	−1.60E − 4	6.24E − 8	3.243	1,942	−394.29	1.251
> C <	0.0042	0.0061	27	21.32	60.15	79.72	87.88	−9.09E + 1	5.57E − 1	−9.00E − 4	4.69E − 7	−1.373	0.644	n. v.	n. v.
= CH–	0.0082	0.0011	41	26.73	8.13	2.09	11.30	−2.14	5.74E − 2	−1.64E − 6	−1.59E − 8	1.101	2.544	259.65	−0.702
= C <	0.0143	0.0008	32	31.01	37.02	46.43	54.05	−8.25	1.01E − 1	−1.42E − 4	6.78E − 8	2,394	3.059	−245.74	0.912
Halogen groups
–F	0.0111	−0.0057	27	−0.03	−15.78	−251.92	−247.19	2.65E + 1	−9.13E − 2	1.91E − 4	−1.03E − 7	1.398	−0.670	n. v.	n. v.
-Cl	0.0105	−0.0049	58	38.13	13.55	−71.55	−64.31	3.33E + 1	−9.63E − 2	1.87E − 4	−9.96E − 8	2.515	4,532	625.45	−1.814
–Br	0.0133	0.0057	71	66.86	43.43	−29.48	−38.06	2.86E + 1	−6.49E − 2	1.36E − 4	−7.45E − 8	3.603	6,582	738.91	−2.038
–I	0.0068	−0.0034	97	93.84	41.69	21.06	5.74	3.21E + 1	−6.41E − 2	1.26E − 4	−6.87E − 8	2.724	9.520	809.55	−2.224
Oxygen groups
–OH ( alcohols )	0.0741	0.0112	28	92.88	44.45	−208.04	−189.20	2.57E + 1	−6.91E − 2	1.77E − 4	−9.88E − 8	2.406	16.826	2173.72	−5.057
-OH ( phenol )	0.0240	0.0184	−25	76.34	82.83	−221.65	−197.37	−2.81	1.11E − 1	−1.16E − 4	4.94E-8	4,490	12,499	3018.17	−7.314
–O– (non-ring)	0.0168	0.0015	18th	22.42	22.23	−132.22	−105.00	2.55E + 1	−6.32E − 2	1.11E − 4	−5.48E − 8	1.188	2,410	122.09	−0.386
–O– (ring)	0.0098	0.0048	13	31.22	23.05	−138.16	−98.22	1.22E + 1	−1.26E − 2	6.03E − 5	−3.86E − 8	5,879	4,682	440.24	−0.953
> C = O (non-ring)	0.0380	0.0031	62	76.75	61.20	−133.22	−120.50	6.45	6.70E − 2	−3.57E − 5	2.86E-9	4.189	8,972	340.35	−0.350
> C = O (ring)	0.0284	0.0028	55	94.97	75.97	−164.50	−126.27	3.04E + 1	−8.29E − 2	2.36E − 4	−1.31E − 7	n. v.	6.645	n. v.	n. v.
O = CH- (aldehyde)	0.0379	0.0030	82	72.24	36.90	−162.03	−143.48	3.09E + 1	−3.36E − 2	1.60E − 4	−9.88E − 8	3.197	9.093	740.92	−1.713
–COOH (acid)	0.0791	0.0077	89	169.09	155.50	−426.72	−387.87	2.41E + 1	4.27E − 2	8.04E − 5	−6.87E − 8	11.051	19,537	1317.23	−2.578
–COO– (ester)	0.0481	0.0005	82	81.10	53.60	−337.92	−301.95	2.45E + 1	4.02E − 2	4.02E − 5	−4.52E − 8	6,959	9.633	483.88	−0.966
= O (other than above)	0.0143	0.0101	36	−10.50	2.08	−247.61	−250.83	6.82	1.96E − 2	1.27E − 5	−1.78E − 8	3,624	5,909	675.24	−1.340
Nitrogen groups
-NH 2	0.0243	0.0109	38	73.23	66.89	−22.02	14.07	2.69E + 1	−4.12E − 2	1.64E − 4	−9.76E − 8	3.515	10.788	n. v.	n. v.
> NH (non-ring)	0.0295	0.0077	35	50.17	52.66	53.47	89.39	−1.21	7.62E − 2	−4.86E − 5	1.05E − 8	5.099	6.436	n. v.	n. v.
> NH (ring)	0.0130	0.0114	29	52.82	101.51	31.65	75.61	1.18E + 1	−2.30E − 2	1.07E − 4	−6.28E − 8	7.490	6,930	n. v.	n. v.
> N– (non-ring)	0.0169	0.0074	9	11.74	48.84	123.34	163.16	−3.11E + 1	2.27E − 1	−3.20E − 4	1.46E − 7	4.703	1,896	n. v.	n. v.
–N = (non-ring)	0.0255	−0.0099	n. v.	74.60	n. v.	23.61	n. v.	n. v.	n. v.	n. v.	n. v.	n. v.	3.335	n. v.	n. v.
–N = (ring)	0.0085	0.0076	34	57.55	68.40	93.70	119.66	5.69	−4.12E − 3	1.28E − 4	−8.88E − 8	3,649	6.528	n. v.	n. v.
= NH	n. v.	n. v.	n. v.	83.08	68.91	93.70	119.66	5.69	−4.12E − 3	1.28E − 4	−8.88-8	n. v.	12,169	n. v.	n. v.
-CN	0.0496	−0.0101	91	125.66	59.89	88.43	89.22	3.65E + 1	−7.33E − 2	1.84E − 4	−1.03E − 7	2,414	12,851	n. v.	n. v.
-NO 2	0.0437	0.0064	91	152.54	127.24	−66.57	−16.83	2.59E + 1	−3.74E − 3	1.29E − 4	−8.88E − 8	9,679	16.738	n. v.	n. v.
Sulfur groups
–SH	0.0031	0.0084	63	63.56	20.09	−17.33	−22.99	3.53E + 1	−7.58E − 2	1.85E − 4	−1.03E − 7	2,360	6.884	n. v.	n. v.
–S– (non-ring)	0.0119	0.0049	54	68.78	34.40	41.87	33.12	1.96E + 1	−5.61E − 3	4.02E − 5	−2.76E − 8	4.130	6.817	n. v.	n. v.
–S– (ring)	0.0019	0.0051	38	52.10	79.93	39.10	27.76	1.67E + 1	4.81E − 3	2.77E − 5	−2.11E − 8	1.557	5.984	n. v.	n. v.

Sample calculation

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

Structural formula of acetone

Acetone (propanone) is the simplest ketone and is divided into three groups according to the Joback method: two methyl groups (–CH ₃ ) and one keto group (C = O). Since the methyl group occurs twice, its contribution is added twice.

	-CH3		> C = O (non-ring)
property	Number of groups	Contribution	Number of groups	Contribution	${\displaystyle \sum G_{i}}$	Calculated value	unit
T c	2	0.0141	1	0.0380	0.0662	500.5590	K
P c	2	−1.20E − 03	1	3.10E-03	7.00E − 04	48.0250	bar
V c	2	65.0000	1	62.0000	192.0000	209.5000	cm 3 / mol
T b	2	23.5800	1	76.7500	123.9100	322.1100	K
T m	2	−5.1000	1	61.2000	51.0000	173.5000	K
H f	2	-76.4500	1	−133.2200	−286.1200	−217.8300	kJ / mol
G f	2	−43.9600	1	−120.5000	−208.4200	−154.5400	kJ / mol
C pa	2	1.95e + 01	1	6.45E + 00	4.55E + 01
C pb	2	−8.08E − 03	1	6.70E − 02	5.08E − 02
C pc	2	1.53E-04	1	−3.57E − 05	2.70E − 04
C pd	2	−9.67E − 08	1	2.86E-09	−1.91E − 07
C p	at T = 300 K					75.3264	J / (mol K)
H m	2	0.9080	1	4.1890	6.0050	5.1250	kJ / mol
H v	2	2.3730	1	8.9720	13.7180	29.018	kJ / mol
η a	2	548.2900	1	340.3500	1436.9300
η b	2	−1.7190	1	−0.3500	−3.7880
η	at T = 300 K					0.0002942	Pa s

Web links

• Online drawing of molecules and material data prediction with the Joback method
• Online assessment of substance data using the Joback method

Individual evidence

1. ↑ ^{a b} K. G Joback, R. C Reid: Estimation of pure-component properties from group-contributions . In: Chemical Engineering Communications . tape 57 , no. 1 , 1987, pp. 233-243 .
2. ↑ A. L Lydersen, R. A Greenkorn, O. A Hougen: Estimation of Critical Properties of Organic Compounds by the Method of Group Contributions . In: Engineering Experiment Station Report . University of Wisconsin, Madison, Wisconsin 1955.
3. ↑ Leonidas Constantinou, Rafiqul Gani: New group contribution method for estimating properties of pure compounds . In: AIChE Journal . tape 40 , no. 10 , October 1994, p. 1697-1710 , doi : 10.1002 / aic.690401011 .
4. ↑ Yash Nannoolal, Jürgen Rarey, Deresh Ramjugernath: Estimation of pure component properties: Part 2. Estimation of critical property data by group contribution . In: Fluid Phase Equilibria . tape 252 , no. 1–2 , February 1, 2007, pp. 1–27 , doi : 10.1016 / j.fluid.2006.11.014 .
5. ^ SE Stein, RL Brown: Estimation of normal boiling points from group contributions . In: Journal of Chemical Information and Computer Sciences . tape 34 , no. 3 , April 1, 1994, pp. 581-587 , doi : 10.1021 / ci00019a016 .