Spectrophotometric Determination of Tertiary Aromatic Amines in the Presence of Primary and Secondary Amines by Com plexation with Tetracyanoethylene SIR: Few colorimetric or spectrophotonietric methods are available for the selective determination of a given tertiary aromatic amine in the presence of primary and secondary aliphatic or aromatic amines. The 3-methyl-2benzothiazolone hydrazine method of Sawicki, Stanley, Hauser, Elbert, and S o e (10) can be applied to tertiary aromatic amines but it also measures primary and secondary aromatic amines as well. The same can be said for the 4 - azobenzenediazonium fluoroborate method of Sawicki, Noe, and Fox ( 9 ) ; however, these authors did show that acetic anhydride could prevent the interference of primary and secondary amines in the colorimetric determination of NJ"dimethylani1ine. The Lauth reaction using PbOn as employed by Jan, Kolsek, and Perpar (3) also determines all three classes of aromatic amines. Specific methods for individual tertiary aromatic amines are available: the Fujiwara reaction, for example, is used for the determination of pyridine (8). Methods of this type cannot be applied to the determination of other tertiary amines, however. Studies of the molecular complexes of tetracyanoethylene ( T C S E ) (6, 11) and the use of T C S E by Peuiifoy and Kager (?) for the estimation of many amines on paper suggested that T C S E might be used for the determination of tertiary aromatic amines. The very high molar absorptivity ( e = 10,500) of the pyridine -TCNE complex (5) and other T C N E complexes indicates that the absorption of light causes a charge-transfer type of electronic transition. However, it does not appear to be clearly established (1) whether complexation of a tertiary aromatic amine in the ground state involves the nonbonding electrons on nitrogen (n donor) or the n electrons of the aromatic ring ( n donorj. Some evidence indicates that N,N-dimethylaniline and pyridine function as n donors toward iodine ( I ) , a markedly different acceptor than TCNE. The most serious analytical problem is that some tertiary aromatic amines and most primary and secondary amines tend to react with T C X E to give colored 4-substituted or iV-substituted tricyanovinyl derivatives (4). The reaction with N,N-dimethylaniline is:
Fortunately this reaction is basecatalyzed (4) and its rate is negligible in weakly acid solution during analytical measurements. The complexation and reaction of T C S E with primary and secondary amines can be drastically reduced by acetylation (11). The use of acetic anhydride raised the question of whether the anhydride would interfere by complexing the tertiary amine as follo.ivs:
Me
Me
0
R3K:
-+
0
I' 11 C-0-C I I
Me
(2)
Ale
Such a complex has been detected b y physical measurement in mixtures of acetic anhydride and the aliphatic amine triethylenediamine, but not in (13). anhydride-pyridine mixtures Such complexation would certainly be deleterious if the tertiary amine acted as an n donor. The method described below was designed to determine a given tertiary aromatic amine in the presence of primary and secondary amines after acetylation of the latter at different concentrations of acetic anhydride, using T C N E . An alternate reagent, 2,4,7-trinitrofluorenone (TNF) was also investigated since T X F complexes more strongly with large ring aromatic amines (12), even in the presence of excess perchloric acid. EXPERIMENTAL
Apparatus. These determinations were carried out using a Beckman D B Spectrophotometer with 1.0-cm. cells and a Bausch and Lomb Spectronic 20 colorimeter using 1.17-cm. cells. Reagents. Tetracyanoethylene ( T C N E ) was obtained from t h e Eastman Kodak Co. and was sublimed at
120' C. under vacuum to obtain a white solid which was stored in a desiccator over sodium hydroxide pellets. Since it is used in large excess, T C S E need not be sublimed for routine work. For careful work, a reagent blank should be used to set 105%T. T C N E solutiolis were saturated solutions in methvlene chloride. The concentration is about 0.09 to 0.1Jf after heating (11). The solutions were used for 1 to 2 weeks. If the solution was not colorless, a reagent blank was used to set 1 0 0 ~ T o for careful work. Acetic anhydride and methylene chloride were reagent grade. Aromatic amines and phenols were Eastman White Label or comparable quality. Procedure. TERTIARY .1RoxkTIc AMINES IS P R E S E X C E O F P R I M A R Y AND SECONDARY X>.rrrcss. T h e sample is weighed accurately into a 25-ml. or larger volumetric flask and dissolved in niet,hylene chloride. From this is taken a 1- to 20-ml. aliquot containing about 5 x mmoles of tertiary amine (see Table I for exact values). The aliquot is transferred to a 50-ml. volumetric flask. Two nil. of acetic anhydride is added to the flask for every estimated 5 X lop3 mmoles of primary or secondary amine. The flask is shaken and allowed to stand for 5 minutes. (Fifteen minutes acet'ylation time was allowed for 2,5-dimethylpiperazine.) h two- or threefold excess of T C X E is added by pipetting 5 ml. of saturated T C X E solution into the flask, giving a final T C S E concentration of about 0.009 to 0.01.1i. (More T C S E may be added in the case of weakly colored T complexes.) The solution is diluted to 50 ml. with niethylene chloride and allowed to stand for 10 to 25 minutes, or until the optimum absorbance is reached. (In the case of pyridine, color development is slower and dependent on temperature. The calibration curve should be controlled within i 0 . 5 ' C. Different calibration curves were obtained by measurements after 35, 75, and 120 minutes a t 24' and 26" C. with higher sensitivity at higher temperatures and longer times. Readings were more stable after 35 minutes than those obtained after 10 minutes. The determination of pyridine in the presence of aniline and similar amines is limited to equimolar concentrat'ions to avoid upward curvature of the calibration curve in the initial portion of the curve.) VOL. 38, NO. 7, JUNE 1966
907
The absorbance is determined at the appropriate wavelength (Table I) and the concentration is read from a standard curve prepared from known concentrations of the tertiary amine containing acetic anhydride a t the same concentrations used for the unknowns.
methylene chloride is used to dilute to volume. The absorbance is read at the appropriate wavelength (Table I). A standard curve is prepared using the same proportions of pentane and methylene chloride as used in the unknown extraction and dilution procedure. N,.V-dimethylaniline and carbazole TERTI.4HY XROMATIC ,$MINES I N PRESEKCE OF PHENOLS BY EXTRACTION.were determined in this manner in the presence of 2,6-dimethoxyphenol, p The sample is weighed accurately methoxyphenol, tert-amylphenol, and into a volumetric flask and dissolved Shell “Ionox R” polyringed phenol. in pentane, preferably, or less preferHeterocyclic amines such as pyridine ably in pentane-methylene chloride or required a higher concentration of methylene chloride alone. From this sodium hydroxide-i.e., 257, aqueous is taken an aliquot of 1 to 5 ml. consolution-to ensure proper extraction. taining no more than 2 ml. of methylene WEAKLY 1 3 . 4 ~ 1 ~AMINES: DCTERchloride, to avoid water pickup in the MIXATION WITH 2,4,7-TRINITROFLCOREextraction. The aliquot should contain NONE. Weakly basic amines were deabout 1 X mmole of tertiary arotermined by dissolving the appropriate matic amine and no more than 0.1 amount of sample (Table 11) in 0.1M mmole of phenol. The aliquot is transperchloric acid-triethyl phosphate solferred to a 50- to 100-ml. separatory vent (12) and adding a 1- to 4-ml. funnel, 10 ml. of 107G aqueous sodium aliquot to 126 mg. of purified 2,4,7hydroxide is added and contacted for trinitrofluorenone (12) in a 5-ml. volu30 seconds, and 10 ml. of dry pentane metric flask. The solution was diluted is added and contacted for one minute. to the mark with 0.1JI perchloric The aqueous layer is withdrawn, and acid-triethyl phosphate, and the abthe sides of the funnel are rinsed twice sorbance was read on the Spectronic 20 with 2-nil. portions of pentane. Any a t 450 mp. A standard curve is preaqueous layer collected is then withpared in the same manner. drawn. The contents of the funnel is emptied into a 50-ml. volumetric flask, and the funnel is rinsed twice with 2-ml. RESULTS A N D DISCUSSION portions of pentane. (Some problems with water carryover were avoided by Solvent Effects. T h e best experipouring the pentane out of the top of mental results were obtained using the funnel occasionally.) The total methylene chloride as the solvent volume of the solution a t this point medium. I n the procedure involving should be no more than 23 ml. to extraction of phenols, a mixture of permit addition of sufficient methylene methylene chloride and pentane, not chloride to keep T C S E in solution. to exceed 4570 pentane, was found If no primary or secondary amine is satisfactory. I n general, chlorinated present, 10 ml. of saturated T C S E in hydrocarbons were preferable to oxymethylene chloride is added, and
Table I. Lower Limit of Detection of Tertiary Amines 0.01M TCNE, 0.4,1.1 AcrO in CHzClz,A = 0.10 Molar absorptivity“ Detected by TCNE, M; Tertiary amine wavelength, mp of final solution 1.6 X 10-4(342) 7 x 101 Triphenylamine 2 x 10-3 (4oob) 5 x 10’ Pyridine 5 x 10-4 (460) 2 x 102 2,5-l)imethylpyrazine N,1Z’-L)imethylaniline 8 X (640) 1 . 5 X lo2 2 . 9 x 10-5(310~) 3 . 5 x 103 1,lO-Pherianthroline 1 x 10-3 (600d) 1 x 102 Carbazole 2 X 10-5(450) 5 x 103 Carbazole-TIL’F‘ 1 X 10-6(440) 1 x 104 Benzidine These molar absorptivities are the slopes of the Beer’s law plots, not the true molar absorptivities as determined by the Benesi-Hildebrand method ( 6 ) . b lleasured after 75-minute reaction at 26” C. c The molar absorptivity of 1,lGphenanthroline alone at 310 mp is 850 ( 2 ) . d Triethyl phosphate solvent. e 0 . 0 l l X TNF in triethyl phosphate solvent. 0
Table II. Determination of Weakly Basic Amines 0.08M TNF, 0.1M HC104-(EtO)3P0 solvent, 450 mw Molar absorptivity Agreement with Beer’s law: of final solution Amine Concentration rangeQ 2 to 8 X 10-4M 210 Carbazole Diphenylamine 0 . 4 to 2 X 10-2M 10 Triphenylamine 0 . 3 to 2 X 10-ZM 14 The lower figure corresponds to A = 0.05 on the Bausch-Lomb Spectronic 20 calorimeter.
908
ANALYTICAL CHEMISTRY
genated or highly polar solvents inas much as the latter tended to promote tricyanovinylation of the aromatic amines by TCNE. Methylene chloride also dissolves up to 0.1M T C N E as well as the required experimental level of most aromatic amines and phenols, even those of molecular weight in excess of 500. Analysis for Tertiary Amines. -4s shown in Table I, various types of tertiary aromatic amines can be determined by complexation with T C N E . Carbazole, a weakly bapic secondary aromatic amine, is unreactive toward acetic anhydride, and can also be determined in t h e presence of other primary and secondary amines. .lpparently the same is true for benzidine. Although 1,lOphenanthroline absorbs ultraviolet light at 310 mb, its molar absorptivity (2) is only one fourth that of the TCSE-1, 10-phenanthroline complex absorbance peak. Beer’s law was obeyed for the amines in Table I from the stated lower limit of concentration to a concentration a t least seven-fold greater than this limit. Comprehensive absorbance data in Table I give the minimum level of amine that can be determined in up to 0.4M acetic anhydride, where the total primary and secondary aromatic amine interferences are at least equimolar. I t should be mentioned here that the complexes of T C S E and aliphatic amines and their decomposition products are only slightly colored so that their interference may be considered minimal above 400 mp. However, the complexes and the N-tricyanovinylamines (4) exhibit rather intense absorption bands in the ultraviolet so that if such interference is suspected, a control determination should be undertaken. Tetracyanoethylene itself exhibits considerable absorption a t 252 and 244 mp in methylene chloride. Concentration of Acetic Anhydride. Although no greater than 1.2 molar acetic anhydride masking agent was found necessary in the room temperature acetylation of primary and secondary amine interference? at equimolar concentrations, excessive quantities (1.631) were found to cause a hypochromic shift. The same effect was observed with a concentration of greater than 457, pentane in methylene chloride in the final solution of amine after the extraction of phenolic interferences. KO greater than a tenfold excess of primary and secondary aromatic amine was present at the lower limit of absorbance readings. Systems of unknown interferences were investigated by plotting total absorbance us. specific increments of anhydride in 0.03-21 T C N E and methylene chloride. In the case of a pure tertiary aromatic amine mixed with primary and
secondary aromatic amine, this curve approaches the absorbance of the tertiary amine-TCNE complex at its absorbance peak. Acetylated primary and secondary aromatic amines investigated showed essentially 100% transmittance at the absorbance peak of the unacetylated amine-TCNE complex. Any variance in this respect for practical systems may be effectively eliminated by employing a methylene chloride-anhydride-TCNE blank. I t was also found that some tertiary aromatic amines such as 2,5-dimethylpyrazine and 3-picoline exhibited such low molar absorptivities that their TCNE complexes could be effectively masked by a 1.6Ji acetic anhydride. These amines did not interfere with the determination of amines such as N , A'-dimethylaniline. It is possible that complexation of 2,5-dimethylpyrazine and 3-picoline by acetic anhydride (as in Equation 2 ) prevents these amines from acting as 12 donors (or possibly T donors) towards T C S E , thus masking them. XJ9-dimethylaniline is too hindered to be strongly complexed even by 1.6X anhydride and will therefore form a colored complex readily with T C K E . Obviously all the tertiary amines studied, including 2,5-diniethylpyrazine and 3-picolineJ are not strongly complexed by 0.4M anhydride and can complex with T C K E in the presence of 0.4-11 anhydride. Effect of Time. Although t h e colors of these complexes darkened over a period of a day, measurements made within a n interval of 10 t o 30 minutes after adding T C N E were reproducible and conforined to Beer's law over the concentration ranges studied. Temperatures above 24' to 25" C. tended to shorten this 20minute interval, especially at t h e lo\$ er concentration limits. N,X-dimethylaniline is known to condense with T C S E to give the deep red 4-tri~yanovinyl-~V,N-dimethylaniline (Equation 1) with a peak at 515 mg, However, i t does so rapidly only in basic solvents such as dimethylformamide a t 50" to 60" C. (4). I n acid solution and at room temperature, i t forms a blue complex with T C N E with a peak at 640 mg. The presence of acetic acid in the acetic anhydride used will retard this reaction long enough for the complex to be measured accurately. The slow increase in absorbance of the pyridine-TCNE system is noteworthy because it was apparently stable enough for its stability constant and molar absorptivity to be measured by BenesiHildebrand plots in methylene chloride ( 5 ) . First, 0.4M acetic anhydride did cause a 7% decrease in the absorbance of a typical TCNE-pyridine mixture in methylene chloride. This possibly indicates a n interaction of anhydride and
Table 111.
Determination of Tertiary Aromatic Amines in the Presence of Primary and Secondary Amines
+
0.02M TCNE 3" Amine, M N,N-Dimethylamine 1.8 x 10-3 Pyridine 2 . 5 X 10-3 2,5-IXmethylpyrazine 4 . 6 x 10-3 N,N-Dimethy laniline 2 x 10-3 Trinhenvlamine
4'x 6 x
fo-4
1,10-Phenanthroline 10-6
1" and 2" Amines, i2.I
+
RIolar absorptivity of final soln.
9 . 2 x 10-30 9 . 2 x 10-30
0.33 0.17
0.17
0.33
1 . 8 X lo2 6 . 8 X 10'
9.2
x 10-3"
0.32
0.32
7 . 0 X 10'
7.8
x
0.25
0.25
1.2
1 . 6 x 10-4b
0.26
0.26
6 . 5 X lo2
1 . 6 x 10-4*
0.20
0.20
3.3
Mixture contains 2,Sdimeth Final ilf of AcsO is 1.2M.
Table IV.
1"
Absorbance 2"N no 1' or 2'147
10-36
~.
x 102
x 103
. - -
Determination of Tertiary Aromatic Amines after Extraction from Phenols
757, CH&l-257, pentane solvent, 0.02M TCXE Absorbance 3" Amine Phenol interference Extracted N o phenols 0 OOlM 0 578 0 584 N,N-Dimethylaniline, 0 OOlM 2 6-IXmethoxyphenolj 0 26OC 0 253 Carbazole, 0 O O 5 M 0 002M a 2,6-Dimethoxyphenol, p-methoxyphenol, and tert-amylphenol. * Solvent was 75y0 (EtO),PO-25% pentane. c The absorbance of the carbazole-2,6-dimethoxyphenolbefore extraction was 0.97.
pyridine (Equation 2). Secondly, whether anhydride was present or not, the absorbance of a typical mixture nearly doubled after standing 35 minutes as compared t o the initial absorbance. Fortunately, after 75 minutes, the increase is slow enough to permit accurate analysis. Analysis of Amine Mixtures. Table 111 gives d a t a for the determination of various tertiary amines in t h e presence of primary and secondary aromatic amines. These amines react rapidly with acetic anhydride a t room temperature and are converted to amides which complex only slightly with T C Y E . I n some cases, a fivefold molar excess of primary and secondary amines could be tolerated after acetylation. Primary and secondary aliphatic amines are better nucleophiles than aromatic amines and acetylate more rapidly at room temperature. Although they were not tested as interferences, i t is apparent from their lack of interferences with the R complexation of T C N E and phenols in acetic anhydride (11) that a two-fold excess of these amines can be tolerated without error. Tertiary aliphatic amines interfere with the above complexation and presumably would interfere in this method also. Phenols react very slowly with acetic anhydride at room temperature and would interfere to varying degrees with
the determination of tertiary aromatic amines. Analysis of Amine-Phenol M i x tures. Since acetic anhydride will not
prevent phenols from interferring with this method, extraction of phenols with sodium hydroxide was attempted. T h e extraction scheme worked best with pentane and 10% aqueous sodium hydroxide, leaving the tertiary aromatic amine in t h e pentane layer. hlethylene chloride was added in sufficient quantity t o t h e pentane t o keep T C S E in solution. The extraction procedure was applied of the determination of S,N-dimethylaniline and carbazole after extraction of various phenols. Table IV shows the results of these determinations. Beer's law was obeyed by the extracted samples. Since water hydrolyzes T C K E , any water carry-over into the pentane layer would be a possible source of error. Although the experimental data appeared to show no such error, the water level in the pentane was determined by the Karl Fischer method according to the modification of Peters and Jungnickel (6). The water concentration was found to be 1.5 p.p.t., corresponding to an error of 0.002 absorbance units. Weakly Basic Aromatic Amines.
T K F has been found to complex more strongly t h a n T C S E with amines and aromatic hydrocarbons having VOL. 38, NO. 7 , JUNE 1966
909
efectively three or more fused rings (1%’)e.g., carbazole, diphenylamine, etc. It has also been observed that 0.1M perchloric acid-triethyl phosphate solvent prevents complexation of T N F and moderately basic amines but does not prevent complexation of T N F and weakly basic amines like carbazole and diphenylamine (1%’). This suggested a very selective method for determining those amines in the presence of more basic primary, secondary, or tertiary amines. ( T K F was used because tjhis phenomenum was not observed with TCKE.) -4s shown in Table 11, carbazole, diphenylamine, and triphenylamine can be colorimetrically determined over the concentration ranges listed. Previous work (12) has already established that amines such as p-naphthylamine, pyridine, and triethylamine should not interfere with this determination. I n
addition, the interference of 1 ,IOphenanthroline and quinoline was tested. When present at 0.01M levels, neither of these amines caused a n increase in absorbance of more than 0.03 units in the absorbance of a solution of TSF-diphenylamine. LITERATURE CITED
(1) Andrews, L. J.,
Keefer, R. M., “Molecular Complexes in Organic Chemistry,” pp. 18-19, Holden-Day, San Francisco, 1964. (2) Badger, G. ?VI., Pearce, R. S., Pettit, R., J . Chem. SOC.1951, 3199. (3) Jan, J., Kolsek, J., Perpar, M., Z. Anal. Chem. 153, 4 (1956). (4) McKusick, B. C., Heckert, R. E., Cairns, T. L., Coffman, D. D., Mower, H. T., J . Am. Chem. Soe. 80, 2806 (19%). (5) Merrifield, 1%. E., Phillips, W. D., Ibid., 80, 2780 (1958). (6) Peters, E. D., Jungnickel, J. L., ANAL.CHEX 27, 450 (1955).
( 7 ) Peurifoy, P. V., Nager, M., Zbid., 32, 1135 (1960). (8) Ploquin, Bull. SOC. Chim. France 1947,700. (9) Sawicki, E., Noe, J. L., Fox, F. T., Talanta 8, 257 (1961). (10) Sawicki, E., Stanley, T. W., Hauser, T. R.. Elbert. W.. ?Joe. J. L.. ANAL. CHEM:33, 722 (1961). ’ ( 1 1 ) Schenk, G. H., Santiago, hI., Wines, P., Zbid., 35, 167 (1963). (12) Schenk, G. H., Vance, P. W., Pietandrea, J., Mojzis, C., Ibid., 37, 372 (1965). (13) Schenk, G. H., Wines, P., Mojeis, C., Zbid., 36, 914 (1964).
GEORGEH. SCHENK PETER WARNER WILLIAMBAZZELLE DeDartment of Chemistrv W i p e State University “ Detroit, Mich. 48202 PRESENTED in part at the 12th Anachem Conference, October, 1964. Work s u p ported by Public Health Research Grant GM-07760 from the National Institutes of Health.
Mercurimetric Determination of Organic Disulfides Using Reaction with Buty Ilithiu m SIR: Disulfides are usually estimated by reduction to thiols-e.g., with zinc ( I ) , sodium borohydride (3) or lithium aluminium hydride (2)-followed by estimation of the thiols produced (2 moles per mole of disulfide). For the estimation of thiols, titration with o-hydroxymercuribenzoate (HMB) in the presence of thiofluorescein as indicator is extremely well suited (4) and the presence of zinc ions does not interfere when excess of EDTA is added. A drawback of the methods of reduction suggested is that the reduction is carried out in acid solution or the excess of reductor has to be destroyed by acidification, and this means that serious errors may be introduced by evaporation for low-boiling members of the series.
Table 1.
Disulfide Methyl
+ RSC4H9
(1) it is seen that 1 mole of thiol is produced per mole of disulfide and a t the same time 1 mole of a thioether is formed. Unfortunately the butyllithiurn is not quite indifferent toward thioethers and to some extent the reaction
+ RSR
CaH9Li
+ RSLi
+ C4H9R
(2)
may take place. This reaction is, however, very slow in comparison with reaction 1 and usually the quantitative
Taken,
25
mg. 1-12
Ethyl
60
40
2-12
Butyl
60
70
5-25
Isopropyl
60
70
5-25
60
25
5-25
Benzyl
10
15
8-40
Trimethylene (:1,2dithiolane)
60
70
4-12
910
+ RSLi
+ CaHgLi
RS-SR
Determination of Organic Disulfides
Reaction with butvllithium Time, T:mp., sec. C. 30
Phenyl
By using butyllithium as the active agent this source of error is eliminated, as the reaction of the solution is kept alkaline all through the estimation. From the equation
ANALYTICAL CHEMISTRY
Errors, % -0.7, +0.6, -1.1, -0.4, -0.8 -0.8, f0.4, -0.6, -0.9, -1.1 -0.9, -0.1, -0.6, -0.5, -0.4 -0.8, 0.0, -0.7, -0.5, +0.4 - 1 . 1 , -0.8, - 0 . 6 , -1.4, -0.5 +0.2, +0.6, -0.4, 0.0, +0.5 -1.6, -1.7, -1.2, -1.5, -1.6
Average recovery,
70
99.5 99.4 99.5 99.7 99.1 100.2 98.5
conversion of disulfide according to 1 can be performed without any remarkable interference of 2. As examples it may be mentioned that after 60 seconds at 70” C. the determination of methyl disulfide results in 1O7y0 recovery, of ethyl disulfide in 10201, and of benzyl disulfide in 120y0 recovery. From Table I it is seen that for the estimation of these three disulfides the teniperatures of 25’ C., 40’ C., and 15’ C., respectively, are recommended, so that even for benzyl disulfide the influence of reaction 2 is negligible. The rate of reactions 1 and 2 depends on the reaction compounds. Some disulfides are quickly converted at room temperature, others need short heating for quantitative conversion. Moreover, the rates of reactions 1 and 2 are somewhat parallel-e.g., dimethyl disulfide is converted very readily a t room temperature according to reaction 1 without any interference of reaction 2, but at higher temperature the interference of reaction 2 between butyllithium and methyl butyl thioether becomes noticeable. On the other hand, isopropyl disulfide reacts quantitatively with butyllithium only a t elevated temperatures. For these reasons it may be difficult to deterrnine the sum of two different disulfidese.g., the two mentioned, in the same sample. Of course the sum of disulfides of similar reactivity to butyllithium can be estimated without difficulties. Aromatic disulfides-e.g., phenyl disulfide-react readily according to
