Quantitative Analysis of Volatile Impurities in

Research ArticleQuantitative Analysis of Volatile Impurities inDiallyldimethylammonium Chloride Monomer Solution by GasChromatography Coupled with Liquid-Liquid Extraction

Cheng Liu Yuejun Zhang Haiying Wang and Weixin Wang

School of Chemical Engineering Nanjing University of Science amp Technology Nanjing 210094 China

Correspondence should be addressed to Yuejun Zhang zhyuejunnjusteducn

Received 1 September 2016 Accepted 15 December 2016 Published 23 January 2017

Academic Editor Valentina Venuti

Copyright copy 2017 Cheng Liu et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The quantitative analysis method for volatile impurities in diallyldimethylammonium chloride (DADMAC) monomer solutionwas established in this paper The volatile impurities were quantitatively analyzed with trichloromethane as extraction solventand n-hexane as internal standard by using gas chromatography (GC) coupled with solvent extraction and the chromatographicconditions quantitative methods and extraction conditions were systematically investigated in detail The results showed thatexcellent linear relationships of 5 volatile impurities (dimethylamine allyldimethylamine allyl chloride allyl alcohol and allylaldehyde) were obtained in the range of 1ndash100mgsdotLminus1 The method also showed good specificity recovery (950ndash1075) andrelative standard deviation (RSD 140ndash767) This method could accurately detect the whole volatile impurities in DADMACmonomer solution quantitatively in one time with a low detection limit Furthermore this method is conducive to the preparationof highly pure DADMAC monomer and the development of national and international standards of the DADMAC monomerproduct quality and the results could provide a strong foundation for the regulation and mechanism research of impurities onmonomer reactivity in polymerization

1 Introduction

Diallyldimethylammonium chloride (DADMAC) is a kindof quaternary ammonium monomer containing two unsat-urated double bonds [1 2] and it usually exists as aqueoussolution because of strong polarity and hygroscopic property[3] DADMAC is a very technologically important monomerand linear polymers of DADMAC can be obtained accordingto Butlerrsquos cyclopolymerization protocol [4] which have beenan attractive method for the polymerization of diallylammo-nium monomers or their copolymerizations [5] Homo- andcopolymers of DADMAC are most widely used cationicwater-soluble polymers in the fields of petroleum [6] dyeing[7] paper making [8] daily chemicals [9] and water treat-ment [10ndash12] because of goodwater solubility easy-controlledpositive charge density and molecular weight and nontoxic-ity in wide range of pH and temperature

As for the DADMAC-based cationic polyelectrolyte withlinear structure the application fields and efficiency are deter-mined by the molecular weight and distribution [13] whenthe cationic unit structure and its ratio in a polymer chainare fixed As a result the research on the products with highand serial molecular weight or the products with controlledmolecular weight distribution is always the key point [14]However for DADMAC-based polymers formed from rad-ical polymerization the species and amounts of impuritiesin DADMAC monomer solution have been considered to beone of the key influencing factors on the polymerization andproduct molecular weights in addition to the polymerizationtechnology [15] the sorts and amounts of initiators [16]and so on Usually the impurities existing in DADMACmonomer solution include residual rawmaterials intermedi-ate products and byproducts [17]The known studies showedthat monomers with different purification levels had different

HindawiInternational Journal of Analytical ChemistryVolume 2017 Article ID 6041459 9 pageshttpsdoiorg10115520176041459

2 International Journal of Analytical Chemistry

polymerization reactivity at the same reaction condition [18]And in particular the intrinsic viscosity of the homopolymerof DADMAC dropped rapidly after adding impurity compo-nents such as intermediate product allyldimethylamine andbyproduct allyl alcohol into the monomer solution purifiedby recrystallization [19] Furthermore the impurities thatremained in the polymer products might be transformedinto toxic and harmful byproducts interfering the applicationperformance of polymers [20 21]

The qualitative and quantitative analysis of impurities inDADMAC monomer solution is the basic mean for accu-rately controlling impurities In the early 1960s Boothe [22]tested the monomers from different purification processes bygas chromatography and the results showed that the peaknumbers and strength of unknown impurity componentsdecreased obviously till disappearance Recently Wang et al[23] transformed the amine salts into volatile organic aminesby adjusting pH with alkali and then measured the absorbedamines in water by titration to determine the total amounts ofamine-impurities inDADMACmonomer solutionHoweverit had failed not only to determine the types and contents ofamines and amine salts but also to concern other impurities

In this study based on the formationmechanismof impu-rities in synthesis process of DADMACmonomer we report-ed the development and validation of a new method usinggas chromatography (GC) coupled with solvent extractionto detect impurities in DADMAC monomer solution Thisquantitative method could forcefully support the research onpreparation technology for high purity DADMACmonomerthe establishment of DADMAC product quality standardand the study on the mechanism and regulation concerningeffects of impurities on monomer polymerization reactivity

2 Materials and Methods

21 Chemicals Dimethylamine (ge998) allyldimethy-lamine (gt990) allyl chloride (gt998) allyl alcohol(gt995) and allyl aldehyde (gt990) were purchased fromSigma-Aldrich (USA) Reagents (methanol ethanol 1-pro-panol isopropanol n-hexane acetone dichloromethanetrichloromethane and ethyl acetate) were of analytical gradeand purchased from Sinopharm Chemical Reagent Co Ltd(China) Double distilled water was used throughout

According to [24] standard solution ofDADMACmono-mer (60wt) was prepared by dissolving DADMAC crystalinto double distilled water

22 Instrument and Analytical Conditions A Bruker GC450gas chromatograph (USA) equipped with a flame ioniza-tion detector (FID) was used for quantification of volatileimpurities Three columns including SE-54 (5 phenyl-95 dimethyl siloxane) PEG-20M (polyethylene glycol)and alkali-modified PEG-20M capillary columns (30m times025mm 025 120583m) were used for the analysis processes Thetemperatures of the injection port and detector were 150 and250∘C respectivelyTheoven temperature began at 40∘C heldfor 20min and increased at a rate of 10∘Csdotminminus1 to 120∘CNitrogen was used as carrier gas at a rate of 20mLsdotminminus1 Avolume of 02 120583L was injected manually in splitless mode

23 Preparation of Standard Solutions Stock solutions of theanalysis standards and internal standard (n-hexane) wereprepared by dissolving them in trichloromethane for finalconcentration of 1000mgsdotLminus1 A series of working solutionswere prepared by diluting the stock solutions to 1 5 10 20 50and 100mgsdotLminus1 with trichloromethane meanwhile internalstandard solution was added into the working solutions withfinal concentration of 20mgsdotLminus1

24 Preparation of Samples The tested DADMACmonomersolution (10mL 60wt) with impurities was placed in a 25mL separatory funnel and then a volume of 10mL extractionsolvent trichloromethane was added into the solution bya pipette The mixture was shaken for 2min then stoodfor several minutes and demixed The extraction phase wasisolated out from the funnel and dried by anhydrous sodiumsulfate-silica gel 01mL internal standard solution was addedinto 40mL of the extraction phase and then the solution wasdiluted to 50mL by trichloromethane for GC analysis

In order to investigate the extraction efficiency stan-dard solution of DADMAC monomer was prepared byadding appropriate amounts of analysis standards and thenprocessed as aforementioned solvent extraction procedureExtraction efficiency (119877) could be calculated as follows

119877 =119860119900119860Standard minus 119860 119894119860Standard119860119900119860Standard

times 100 (1)

where119860119900119860Standard and119860 119894119860Standard were the peak area ratiosof impurities versus internal standard before and after extrac-tionThe arithmeticmeanof extraction efficiencies at concen-trations of 10 50 and 90mgsdotLminus1 was defined as the extractionefficiency of the impurity in the solvent extraction procedure

3 Results and Discussion

31 Formation of Volatile Impurities DADMAC monomerwas prepared by the reaction of dimethylamine with allylchloride and sodium hydroxide and the general reactionequation was as follows

2CH2=CHCH2Cl + (CH3)2NH + NaOH 997888rarr

(CH2=CHCH2)2N+ (CH3)2 Cl

minus + NaCl +H2O(2)

The whole reaction process could be divided into twosteps including alkylation of dimethylamine and the qua-ternarization Alkylation of dimethylamine referred to SN2nucleophilic substitution reaction of allyl chloridewith nucle-ophilic reagent dimethylamine [9] The Cl atom in allylchloridewas very active to be substituted and dimethylaminewith strong alkality (p119870119887 = 327) was also a strong nucle-ophilic agent [25] so this reaction could be carried out atlow temperature But it was also an exothermic reaction andcooling was essential otherwise problems such as more sidereactions and loss of volatile rawmaterials would appearThegeneral equation of alkylation was as follows

(CH3)2NH + CH2=CHCH2Cl 997888rarr

CH2=CHCH2N (CH3)2 +HCl(3)

International Journal of Analytical Chemistry 3

Quaternarization referred to the formation of quaternaryammonium salt by the reaction of allyldimethylamine withallyl chloride [3] This reaction was essentially also a SN2nucleophilic substitution reaction The nucleophilic reagentwas allyldimethylamine with weaker alkality and strongersteric effect than dimethylamine so this reaction needed ahigher temperature [17] The general equation of alkylationwas as follows

CH2=CHCH2N (CH3)2 + CH2=CHCH2Cl 997888rarr


minus(4)

In addition there were some other side reactions Anequal amount of HCl companying with the formation oftertiary amine would be produced according to the alkylationreaction And HCl would then react with dimethylamineimmediately to form dimethylamine hydrochloride Thereaction equation was as follows

(CH3)2NH +HCl 997888rarr (CH3)2NHsdotHCl (5)Of course HCl could also react with allyldimethylamine

to form hydrochloride

CH2=CHCH2N (CH3)2 +HCl 997888rarr

CH2=CHCH2N (CH3)2 sdotHCl(6)

Since the alkality of dimethylamine was stronger thanallyldimethylamine the formation of dimethylamine hydro-chloride occupied a larger portion Because salification ofamines prohibited the nucleophilic reaction and quaternar-ization [25] alkali should be added to neutralize HCl and torelease the two amines The reaction equations of neutraliza-tion were as follows

(CH3)2NHsdotHCl +NaOH 997888rarr

(CH3)2NH +NaCl +H2O(7)

CH2=CHCH2N (CH3)2 sdotHCl +NaOH 997888rarr

CH2=CHCH2N (CH3)2 +NaCl +H2O(8)

However the allyl chloride existed together with aminesin the reaction system which would be hydrolyzed to gener-ate allyl alcohol when OHminus was added

CH2=CHCH2Cl +NaOH 997888rarr

CH2=CHCH2OH +NaCl(9)

It could be seen that the byproducts of the wholereaction process included the unreacted raw materialssuch as dimethylamine ((CH3)2NH) and allyl chloride(CH2=CHCH2Cl) the intermediate products such as dim-ethylamine hydrochloride ((CH3)2N

+H2Cl) allyldimethy-lamine (CH2=CHCH2N(CH3)2) and its hydrochloride salt(CH2=CHCH2N

+H(CH3)2Clminus) and the other byproducts

such as allyl alcohol (CH2=CHCH2OH) from the hydrolyza-tion of allyl chloride in alkaline medium and allyl aldehyde(CH2=CHCHO) from oxidation of allyl alcohol

In this paper we particularly focused on volatile impu-rities which would cause undesirable inhibition and retarda-tion effect in polymerization process

32 Optimization of Chromatographic Conditions

321 Selection of Chromatographic Columns Consideringthe principle of ldquolike dissolves likesrdquo in column stationaryphase selection together with boiling points and polarity(dipole moment) of impurities [24] three kinds of columnswith increasing polarity including SE-54 PEG-20M andalkali-modified PEG-20M were chosen for the GC analysis

For SE-54 column impurities peaks and solvents peaksoverlapped together to form only one peak even when usingvarious solvents accompanied with adjusting GC conditions(Figure 1(a)) For PEG-20M column the chromatogramusing trichloromethane as the solvent was shown as inFigure 1(b) and the peaks of allyl chloride allyl aldehydeand allyl alcohol could be completely separated However theseparation between dimethylamine and allyldimethylaminewas not ideal so the polarity of column should be adjustedto obtain a desirable separation effect of these two amineson the basis of good separation of other analytes Thereforean alkali-modified PEG-20M column was used in the sepa-ration For alkali-modified PEG-20M column the separationeffect of possible volatile impurities including the two amineswas enhanced clearly (Figure 1(c)) The total retention timehere was very short so it was suitable for the analysis of allthe possible volatile impuritiesTherefore themodified PEG-20M column was chosen as the separation column in thispaperThepolarity of dimethylamine and allyldimethylaminewas close and the retention timewas almost the same so theycould not be remarkably separated by PEG-20M columnBecause both of the two amines were alkaline and the alkalityof dimethylamine was stronger than that of allyldimethy-lamine amethod of alkali modification on the PEG-20M col-umn was applied to shorten retention time of more alkalinedimethylamine and to prolong retention time of less alkaliallyldimethylamine and the separation effect of the twoamines was obviously improved

322 Determination of Analysis Conditions Figure 2 showsseparation effect with different initial column temperatureand carrier gas flow rate Considering the boiling point rangeof the 5 possible volatile impurities being 69sim969∘C theoptimization conditions were tested by setting initial columntemperatures of 40 50 and 60∘C and carrier gas flow rates of10 20 and 30mLsdotminminus1 respectively Among them the sepa-ration degree and peak shape were fine with column temper-ature of 40∘C and flow rate of 20mLsdotminminus1 (Figure 2(b)) andthe impurities could separate with each other Usually lowtemperature and low flow rate resulted in long retention timewhile high temperature and high flow rate made it difficult toseparate components In 5 possible volatile impurities theboiling point of dimethylamine was low (69∘C) and that ofallyl alcohol was high (969∘C) and the others were 40ndash60∘Cmeanwhile there existed the effect of polarity so the selectedcolumn temperature 40∘C could satisfy the requirement ofseparation

Because of the wide boiling point range of analytes aconstant column temperature was unfavorable to multicom-ponent separationUsually a programmed temperature couldmake the column temperature corresponding to the boiling


Time (min)

Sign

al (m

V)

10

20

30

40

50

60

0

1086420

s

(a)

Sign

al (m

V)

10

20

30

40

50

60

0

Time (min)10 1286420

s

1

2

3

4

5

(b)

Sign

al (m

V)

10

20

30

40

0

Time (min)10 128642

s

1

2

3

4 5

(c)

Figure 1 Typical chromatogram with different separation columns of SE-54 (a) PEG-20M (b) and alkali-modified PEG-20M (c) Peakssolvent (s) dimethylamine (1) allyldimethylamine (2) allyl chloride (3) allyl aldehyde (4) and allyl alcohol (5)

points of analytes so the components with low and high boil-ing points could be isolated enough with suitable retentiontime and the peak shape was fine Heating rates of 5 10 15 2025∘Csdotminminus1 were investigated in this paper Figure 3 showedthat the better separation effect could be obtained with heatrate of 10∘Csdotminminus1 by comparing the chromatograms of con-stant temperature in particular the peak shape of allyl alcoholwas obviously improved with programmed temperature

33 Selection of Quantitative Methods

331 Comparison of Internal and External Standard MethodsExternal standard method and internal standard method arecommonly used quantitative methods for chromatography[26] For the former method the sampling condition shouldbe paid more attention to ensuring the sample quantityprecisely and parallelly For the latter method the key point

was the selection of internal standards being stable and notoverlapping with peaks of the analytes Therefore standardsolutions of allyl chloride with high medium and low con-centrations were detected by external and internal standardmethods byGC and the results of 5 consecutive samples wereshown inTable 1The results showed that the relative standarddeviation (RSD) of peak areas (119860 119894) were relatively large suchas 1158ndash1742 for allyl chloride when using external stan-dardmethod while the RSDof peak area ratios (119860 119894119860Standard)were only 141ndash227 when using internal standardmethodThe reasonwas that stable operating conditions pre-cise sampling amounts and good repeatability were requiredfor external standard method and the sampling error wouldbe accumulated and calculated into the RSD but samplingerror would not affect the RSD for internal standard methodSo the internal standard method was chosen for the analysisof impurities to ensure the accuracy of detection results


Sign

al (m

V)

10

20

0

Time (min)10 128642

5

15

1

2

3

4

s

(a)

Sign

al (m

V)

0

Time (min)10 128642

0

6

8

10

4

2

51

3

4

s

(b)

Time (min)10 128642

s

1

2

3

4

Sign

al (m

V)

0

6

8

10

4

25

(c)

Time (min)108642

s

1

2

3

4

Sign

al (m

V)

5

6

8

10

9

7

(d)

Figure 2 Effect of initial temperature and carrier gas flow rate of (a) 40∘C and 10mLsdotminminus1 (b) 40∘C and 20mLsdotminminus1 (c) 50∘C and20mLsdotminminus1 and (d) 50∘C and 30mLsdotminminus1 Peaks solvent (s) dimethylamine (1) allyldimethylamine (2) allyl chloride (3) allyl aldehyde(4) and allyl alcohol (5)

Table 1 Comparison of external and internal standard methods

Methods Conc (mg Lminus1) Found RSD ()

External standard method (peak area 119860 119894)10 938 854 1305 1042 1202 173530 2741 2983 3364 3687 3051 115850 3801 6132 5349 5895 5859 1742

Internal standard method (peak area ratio 119860 119894119860Standard)10 0419 0413 0412 0427 0420 14530 125 124 130 129 124 22750 221 214 215 219 216 141

332 Selection of Internal Standards According to therequirement of internal standard [24] several commonlyused organic compounds and solvents including methanolethanol propanol isopropanol 119899-hexane and acetone(Table 2) were selected as the internal standards consideringthe boiling points and polarity of impurities and solvents

The results showed that the retention time of n-hexane was346min and it could be completely separated with impu-rities of allyl chloride (416min) allyl aldehyde (468min)allyl alcohol (993min) dimethylamine (382min) andallyldimethylamine (399min) and extraction solvent of tri-chloromethane and there were no chemical reactions


Sign

al (m

V)

Time (min)10 128642

6

8

10

12

14

4

2

1

2

3

4

5

s

(a)

Time (min)10 128642

Sign

al (m

V)

8

12

16

4

1

2

3

4

5

s20

0

(b)

Figure 3 Typical chromatogramwith different heating rates of (a) constant temperature and (b) 10∘Csdotminminus1 Peaks solvent (s) dimethylamine(1) allyldimethylamine (2) allyl chloride (3) allyl aldehyde (4) and allyl alcohol (5)

Table 2 Calibration curve and LODs for allyl chloride and its derivatives

Impurities Concentration range (mg Lminus1) Equation 1198772 LOD (mg Lminus1)Dimethylamine 1ndash100 119910 = 00283119909 minus 01581 09974 02Allyldimethylamine 1ndash100 119910 = 00270119909 minus 00080 09966 01Allyl chloride 1ndash100 119910 = 00436119909 + 00075 09976 01Allyl alcohol 1ndash100 119910 = 00417119909 + 00586 09942 01Allyl aldehyde 1ndash100 119910 = 00179119909 minus 00673 09924 02

between n-hexane and the analytes so n-hexane was chosenas the internal standard The gas chromatogram with n-hexane as internal standard and trichloromethane as extrac-tion solvent was shown in Figure 4

34 Optimization of Extraction

341 Effect of Monomer Concentration The solvent extrac-tion procedure was used to separate volatile impurities inmonomer aqueous solution However extraction efficiencyof impurities would be affected by whether the organic phasecould fully be mixed with aqueous phase in extraction andthen well demixed with aqueous phase after extraction [27]As the apparent viscosity change of DADMAC monomersolution caused by changing mass fraction would have aninfluence on the extraction efficiency a suitable solution con-centration should be determined by experiments Accord-ingly the concentrations of DADMAC monomer solutionswere adjusted to 0wtndash60wt by double distilled waterwhile the concentration of impurities was set at 50mgsdotLminus1Then the DADMAC samples were analyzed and the resultsin Figure 5 showed that with the increase of monomerconcentration the extraction efficiency decreased graduallyThe reason might be that the raising viscosity of DADMACsolution might lead to inadequate mix of extraction solventwith monomer solution and poor separation effect of them

Time (min)10 128642

Sign

al (m

V)

6

12

15

3

9

0

1 2

3

4

5

6

Figure 4 Chromatogramof internal standard and impurities (mod-ified PEG-20M capillary column Peaks 1 119899-hexane 2 dimethy-lamine 3 allyldimethylamine 4 allyl chloride 5 allyl aldehyde 6allyl alcohol)

after extraction Moreover the change of monomer concen-trationwould change the polarity of the aqueous layer and thedistribution of impurities between organic layer and aqueous

International Journal of Analytical Chemistry 7A

iA

Inte

rnal

stand

ard

DimethylamineAllyldimethylamineAllyl chlorideAllyl alcoholAllyl aldehyde

w(DADMAC) ()

20

18

16

14

12

10

08

06

6050403020100

Figure 5 Effect of DADMAC concentration on the peaks ofanalytes

layer would be affected accordingly However the concen-tration of impurities decreased together with the decrease ofDADMAC concentration and it was also unfavorable for thequantitative accuracyTherefore DADMAC concentration of30wt was chosen for the subsequent experiments

342 Investigation of Extraction Solvents The extractionsolvent was extremely important for extraction efficiency ofimpurities in a quantitativemethod [26 27] so the extractionsolvents such as dichloroethane trichloromethane and ethylacetate were further investigated for the qualitative analysisfor dimethylamine and allyldimethylamine The results asin Figure 6 showed that the extraction efficiency of thesolvent trichloromethane was the highest for dimethylamineallyldimethylamine allyl chloride allyl alcohol and allylaldehyde with the values of 703 877 979 661 and840 respectively Generally considering the principle ofldquolike dissolves likesrdquo the solubility of volatile impuritieswould be larger in solvents with higher polarity namelyhigher extraction efficiency However although the polarityof ethyl acetate was similar to that of trichloromethane(with 119899-hexane polarity of 0 as the reference the polarity oftrichloromethane was 44 and polarity of ethyl acetate was43) [25] the water solubility of ethyl acetate (83 g in 100mLwater at 20∘C) [25] was much higher than the latter There-fore a certain amount of impurities would be still left anddistributed in the aqueous phase after the extraction by ethylacetate and the extraction efficiency was lower accordinglyFigure 6 also showed that the extraction efficiency of allylalcohol was lower than that of the other two impurities byusing all kinds of solvents and this might be due to the highsolubility of allyl alcohol in water because of the high polarity


Extr

actio

n effi

cien

cy (

)

Dichloromethane Trichloromethane Ethyl acetate

100

80

60

40

20

0

Figure 6 Effect of solvents on extraction efficiency

35 Method Validation

351 Calibration and Limits of Detection (LOD) The cali-bration curves were created with the serial mixed workingstandard solutions of impurities and constructed by plottingthe peak area ratio of impurities (119860 119894119860Standard) as ordinateversus the concentration of impurities as abscissa The limitof detection (LOD) was determined as 31198780 where 1198780 is thestandard deviation as the concentration approaches zeroTheresults of calibration curves and LODs in Table 2 showedgood linear relationship (1198772 gt 0992) in the range of 1ndash100mgsdotLminus1 with LODs of 01ndash02mgsdotLminus1

352 Precision and Recovery Precision and recovery ofthe established method were evaluated with spiked samplesat three concentration levels for the impurities-containingDADMAC monomer solutions The concentration of impu-rities could be calculated by the peak area ratio (119860 119894119860Standard)and calibration curves and the results were listed in Table 3From the table it could be seen that the recoveries ofdimethylamine allyldimethylamine allyl chloride allyl alco-hol and allyl aldehyde were 956ndash1075 994ndash1041950ndash1033 956ndash989 and 969ndash995with RSDs of167ndash595 159ndash249 145ndash221 197ndash375 and140ndash205 respectively The established method showedgood precisions and recoveries for all three impurity com-pounds despite the three different concentration levels andit could entirely meet the needs of precisely quantitativeanalysis for them

36 Analysis of DADMAC Samples Some self-made DAD-MAC samples in lab and in pilot plants and the commercialDADMAC samples from representative companies in Chinawere chosen to analyze the contents of volatile impuritiesTheresults in Table 4 showed that the contents of these impurities


Table 3 Precision and recovery for allyl chloride and its derivatives (119899 = 6)

Impurities Initial found (mg Lminus1) Added (mg Lminus1) Total found (mg Lminus1) Recovery () RSD ()

Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167

Allyldimethylamine2485 250 4955 994 1593244 300 6468 1036 1744159 400 8493 1041 249

Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173

Table 4 Analytical results for several real DADMAC samples

Samples Impurities contents (mg Lminus1)[120578] (dL gminus1)

Dimethylamine Allyldimethylamine Allyl chloride Allyl aldehyde Allyl alcohol50 g grade lab experiment 18496 40722 4582 130518 8592 unreactive50 kg grade pilot test P6 ND ND ND ND ND 317500 kg grade pilot test AZ ND 4751 6375 ND ND 043Jiangsu Feymer Technology Co Ltd ND ND ND ND ND 231Shandong Luyue Chemical Co Ltd ND 14733 1704 496 ND 088Shandong Polymer Bio-Chemicals Co Ltd ND 2924 ND ND ND 184Hangzhou Yinhu Chemical Co Ltd 27206 37545 11815 7429 ND 013ND = not detected

in DADMAC samples were different from each other Themolecular weights (calculated by intrinsic viscosity [120578]) ofpoly-DADMACs changed with the variation of the sorts ofimpurities and their contents even under the same optimumpolymerization condition [14] so that it could further notonly prove the obvious effect of the impurities on themolecu-lar weight of polymer products but also illustrate the impor-tance to establish a product quality standard for promotingthe overall level of the DADMAC production in industry

4 Conclusions

A novel method of GC coupled with solvent extraction forthe quantitative analysis of volatile impurities in DADMACmonomer solution was established with trichloromethane asextraction solvent and n-hexane as internal standard Theresults showed excellent linear relationships of 5 volatileimpurities (dimethylamine allyldimethylamine allyl chlo-ride allyl alcohol and allyl aldehyde) in the range of 1ndash100mgsdotLminus1 together with good specificity recovery (950ndash1075) and relative standard deviation (RSD 140ndash767)Finally several DADMAC samples were analyzed success-fully using thismethod and a satisfactory result was obtained

The established quantitative determination method not onlycan have industrial application value because of simplicityspeediness and accuracy but also can provide a foundationfor the establishment of DADMAC product quality standardand the research on the regulation and mechanism concern-ing the effect of impurities on DADMAC polymerizationreactivity

Competing Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (21377054) the Science and technologyGuidance Program of China Petroleum and Chemical Indus-try Federation in 2013 and the National Key TechnologyResearch and Development Program of China during theldquo10th Five-Year Planrdquo (2003BA327C)


References

[1] A Matsumoto ldquoPolymerization of multiallyl monomersrdquoProgress in Polymer Science vol 26 no 2 pp 189ndash257 2001

[2] G B Butler and R T Angelo ldquoPreparation and polymeriza-tion of unsaturated quaternary ammonium compounds VIIIA proposed alternating intramolecular-intermolecular chainpropagationrdquo Journal of the American Chemical Society vol 79no 12 pp 3128ndash3131 1957

[3] C Wandrey J Hernandez-Barajas and D Hunkeler ldquoDial-lyldimethylammonium chloride and its polymersrdquo AdvancedPolymer Science vol 145 pp 123ndash182 1999

[4] G B Butler Cyclopolymerization and CyclocopolymerizationMarcel Dekker New York NY USA 1992

[5] OC SAl-Hamouz and SAAli ldquopH-responsive polyphospho-nates using butlerrsquos cyclopolymerizationrdquo Journal of PolymerScience Part A Polymer Chemistry vol 50 no 17 pp 3580ndash3591 2012

[6] L Lin and P Y Luo ldquoHydrolyzed AMDMDAACAMPScopolymer functioning as filtration reducer for brine saturateddrilling fluids under high temperature and high pressurerdquo FineChemicals vol 31 pp 1417ndash1421 2014

[7] X Y Liu X F Wang and L Zhou ldquoAntistatic propertiesof PDMDAACAM on polyester fabricsrdquo Journal of TextileResearch vol 33 pp 92ndash96 2012

[8] R X Yan Water-Soluble Polymer Chemical Industry PressBeijing China 2nd edition 2010

[9] Y Q Xiong L Tao Z Q He and Y P Zhou ldquoStudy on theapplied behaviors of dimethyldiallylammoniumchloride as hairconditionerrdquo China Surfactant Detergent and Cosmetics vol 5pp 25ndash27 1999

[10] Z Yang B Gao Y Wang X Zhang and Q Yue ldquoRelationshipbetween residual Al species floc operational parameters andcoagulation performance during reservoir water treatment byPAC-PDMDAACrdquo Separation and Purification Technology vol102 pp 147ndash156 2013

[11] N E Kuzrsquomina S V Moiseev V I Krylov V A Yashkir and VA Merkulov ldquoDetermination of the parameters of molecular-weight distribution of hydroxyethyl starches by diffusion-ordered NMR spectroscopyrdquo Journal of Analytical Chemistryvol 70 no 7 pp 843ndash849 2015

[12] J Su X Liu J Hu Q You Y Cui and Y Chen ldquoPhoto-inducedcontrolled radical polymerization ofmethylmethacrylatemedi-ated by photosensitive nitroxidesrdquo Polymer International vol64 no 7 pp 867ndash874 2015

[13] Y J Zhang and X Jia ldquoSynthesis of ultra high molecular weightpoly(dimethyldiallyl ammonium chloride)rdquo Russian Journal ofApplied Chemistry vol 89 no 2 pp 315ndash323 2016

[14] X Jia and Y Zhang ldquoEffects of maintaining temperature andtime on properties and structures of poly(dimethyldiallylam-monium chloride)rdquo Journal of Applied Polymer Science vol 125no 1 pp 1ndash9 2012

[15] A Nagaki M Takumi Y Tani and J-I Yoshida ldquoPolymer-ization of vinyl ethers initiated by dendritic cations using flowmicroreactorsrdquo Tetrahedron vol 71 no 35 pp 5973ndash5978 2015

[16] K Shen D Qi Y Li X Zhao and Y Li ldquoControlled emul-sion polymerization of styrene and methylmethacrylate in thepresence of amphiphilic tertiary amine N-oxidesrdquo Colloids andSurfaces A Physicochemical and Engineering Aspects vol 482pp 728ndash733 2015

[17] C Liu and Y J Zhang ldquoA study on the synthesis of dimethyl-diallylammonium chloriderdquo Fine Chemicals vol 31 no 3 pp86ndash72 2014

[18] Y M Quan X G Hu and M X Wang ldquoImprovements insynthesis and analysis of dimethyl diallyl ammonium chloriderdquoOilfield Chemistry vol 14 no 2 pp 159ndash161 1997

[19] J E Boothe H G Flock and M Fred Hoover ldquoSome homo-and copolymerization studies of dimethyldiallylammoniumchloriderdquo Journal of Macromolecular Science Part A - Chem-istry vol 4 no 6 pp 1419ndash1430 1970

[20] S-H Park S Wei B Mizaikoff A E Taylor C Favero andC-H Huang ldquoDegradation of amine-based water treatmentpolymers during chloramination as N-nitrosodimethylamine(NDMA) precursorsrdquo Environmental Science amp Technology vol43 no 5 pp 1360ndash1366 2009

[21] L Padhye Y LuzinovaM Cho BMizaikoff J-H Kim and C-H Huang ldquoPolyDADMAC and dimethylamine as precursorsofN-nitrosodimethylamine during ozonation reaction kineticsand mechanismsrdquo Environmental Science amp Technology vol 45no 10 pp 4353ndash4359 2011

[22] J E Boothe ldquoProcess for purifying dialkyl diallyl ammoniumchloride and dialkyl dimethallyl ammonium chloriderdquo USPatent 3472740 1967

[23] H Wang X X Jin J Sun and X G Hu ldquoStudy on thedetermination of the content of organic amine impurities inDMDAACrdquo IndustrialWater Treatment vol 29 pp 59ndash61 2009

[24] S Shuji S Masatoshi and F Yoshiaki ldquoDiallyldimethylammo-nium halide monomersrdquo JP Patent 60184052 1985

[25] Q Y Xing W W Pei R Q Xu and J Pei Basic OrganicChemistry Chemical Industry Press Beijing China 3rd edi-tion 2005

[26] Z F Wang Quanlitification and Quantificatioan of Chromatog-raphy Chemical Industry Press Beijing China 2nd edition2007

[27] L Wang Z F Wang and S F Mou Sample Treatment forChromatography Chemical Industry Press Beijing China 2ndedition 2006

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

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International Journal ofPhotoenergy


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Journal of

Chemistry


Advances in

Physical Chemistry

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Analytical Methods in Chemistry

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Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


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Medicinal ChemistryInternational Journal of


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Applied ChemistryJournal of



Theoretical ChemistryJournal of


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Analytical ChemistryInternational Journal of


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polymerization reactivity at the same reaction condition [18]And in particular the intrinsic viscosity of the homopolymerof DADMAC dropped rapidly after adding impurity compo-nents such as intermediate product allyldimethylamine andbyproduct allyl alcohol into the monomer solution purifiedby recrystallization [19] Furthermore the impurities thatremained in the polymer products might be transformedinto toxic and harmful byproducts interfering the applicationperformance of polymers [20 21]

The qualitative and quantitative analysis of impurities inDADMAC monomer solution is the basic mean for accu-rately controlling impurities In the early 1960s Boothe [22]tested the monomers from different purification processes bygas chromatography and the results showed that the peaknumbers and strength of unknown impurity componentsdecreased obviously till disappearance Recently Wang et al[23] transformed the amine salts into volatile organic aminesby adjusting pH with alkali and then measured the absorbedamines in water by titration to determine the total amounts ofamine-impurities inDADMACmonomer solutionHoweverit had failed not only to determine the types and contents ofamines and amine salts but also to concern other impurities

In this study based on the formationmechanismof impu-rities in synthesis process of DADMACmonomer we report-ed the development and validation of a new method usinggas chromatography (GC) coupled with solvent extractionto detect impurities in DADMAC monomer solution Thisquantitative method could forcefully support the research onpreparation technology for high purity DADMACmonomerthe establishment of DADMAC product quality standardand the study on the mechanism and regulation concerningeffects of impurities on monomer polymerization reactivity

2 Materials and Methods

21 Chemicals Dimethylamine (ge998) allyldimethy-lamine (gt990) allyl chloride (gt998) allyl alcohol(gt995) and allyl aldehyde (gt990) were purchased fromSigma-Aldrich (USA) Reagents (methanol ethanol 1-pro-panol isopropanol n-hexane acetone dichloromethanetrichloromethane and ethyl acetate) were of analytical gradeand purchased from Sinopharm Chemical Reagent Co Ltd(China) Double distilled water was used throughout

According to [24] standard solution ofDADMACmono-mer (60wt) was prepared by dissolving DADMAC crystalinto double distilled water

22 Instrument and Analytical Conditions A Bruker GC450gas chromatograph (USA) equipped with a flame ioniza-tion detector (FID) was used for quantification of volatileimpurities Three columns including SE-54 (5 phenyl-95 dimethyl siloxane) PEG-20M (polyethylene glycol)and alkali-modified PEG-20M capillary columns (30m times025mm 025 120583m) were used for the analysis processes Thetemperatures of the injection port and detector were 150 and250∘C respectivelyTheoven temperature began at 40∘C heldfor 20min and increased at a rate of 10∘Csdotminminus1 to 120∘CNitrogen was used as carrier gas at a rate of 20mLsdotminminus1 Avolume of 02 120583L was injected manually in splitless mode

23 Preparation of Standard Solutions Stock solutions of theanalysis standards and internal standard (n-hexane) wereprepared by dissolving them in trichloromethane for finalconcentration of 1000mgsdotLminus1 A series of working solutionswere prepared by diluting the stock solutions to 1 5 10 20 50and 100mgsdotLminus1 with trichloromethane meanwhile internalstandard solution was added into the working solutions withfinal concentration of 20mgsdotLminus1

24 Preparation of Samples The tested DADMACmonomersolution (10mL 60wt) with impurities was placed in a 25mL separatory funnel and then a volume of 10mL extractionsolvent trichloromethane was added into the solution bya pipette The mixture was shaken for 2min then stoodfor several minutes and demixed The extraction phase wasisolated out from the funnel and dried by anhydrous sodiumsulfate-silica gel 01mL internal standard solution was addedinto 40mL of the extraction phase and then the solution wasdiluted to 50mL by trichloromethane for GC analysis

In order to investigate the extraction efficiency stan-dard solution of DADMAC monomer was prepared byadding appropriate amounts of analysis standards and thenprocessed as aforementioned solvent extraction procedureExtraction efficiency (119877) could be calculated as follows

119877 =119860119900119860Standard minus 119860 119894119860Standard119860119900119860Standard

times 100 (1)

where119860119900119860Standard and119860 119894119860Standard were the peak area ratiosof impurities versus internal standard before and after extrac-tionThe arithmeticmeanof extraction efficiencies at concen-trations of 10 50 and 90mgsdotLminus1 was defined as the extractionefficiency of the impurity in the solvent extraction procedure

3 Results and Discussion

31 Formation of Volatile Impurities DADMAC monomerwas prepared by the reaction of dimethylamine with allylchloride and sodium hydroxide and the general reactionequation was as follows

2CH2=CHCH2Cl + (CH3)2NH + NaOH 997888rarr


minus + NaCl +H2O(2)

The whole reaction process could be divided into twosteps including alkylation of dimethylamine and the qua-ternarization Alkylation of dimethylamine referred to SN2nucleophilic substitution reaction of allyl chloridewith nucle-ophilic reagent dimethylamine [9] The Cl atom in allylchloridewas very active to be substituted and dimethylaminewith strong alkality (p119870119887 = 327) was also a strong nucle-ophilic agent [25] so this reaction could be carried out atlow temperature But it was also an exothermic reaction andcooling was essential otherwise problems such as more sidereactions and loss of volatile rawmaterials would appearThegeneral equation of alkylation was as follows

(CH3)2NH + CH2=CHCH2Cl 997888rarr

CH2=CHCH2N (CH3)2 +HCl(3)





minus(4)

























Time (min)

Sign

al (m

V)

10

20

30

40

50

60

0

1086420

s

(a)

Sign

al (m

V)

10

20

30

40

50

60

0

Time (min)10 1286420

s

1

2

3

4

5

(b)

Sign

al (m

V)

10

20

30

40

0

Time (min)10 128642

s

1

2

3

4 5

(c)







Sign

al (m

V)

10

20

0

Time (min)10 128642

5

15

1

2

3

4

s

(a)

Sign

al (m

V)

0

Time (min)10 128642

0

6

8

10

4

2

51

3

4

s

(b)

Time (min)10 128642

s

1

2

3

4

Sign

al (m

V)

0

6

8

10

4

25

(c)

Time (min)108642

s

1

2

3

4

Sign

al (m

V)

5

6

8

10

9

7

(d)









Sign

al (m

V)

Time (min)10 128642

6

8

10

12

14

4

2

1

2

3

4

5

s

(a)

Time (min)10 128642

Sign

al (m

V)

8

12

16

4

1

2

3

4

5

s20

0

(b)







Time (min)10 128642

Sign

al (m

V)

6

12

15

3

9

0

1 2

3

4

5

6




iA

Inte

rnal

stand

ard


w(DADMAC) ()

20

18

16

14

12

10

08

06

6050403020100





Extr

actio

n effi

cien

cy (

)


100

80

60

40

20

0









Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167


Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173





4 Conclusions



Competing Interests


Acknowledgments



References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





minus(4)

























Time (min)

Sign

al (m

V)

10

20

30

40

50

60

0

1086420

s

(a)

Sign

al (m

V)

10

20

30

40

50

60

0

Time (min)10 1286420

s

1

2

3

4

5

(b)

Sign

al (m

V)

10

20

30

40

0

Time (min)10 128642

s

1

2

3

4 5

(c)







Sign

al (m

V)

10

20

0

Time (min)10 128642

5

15

1

2

3

4

s

(a)

Sign

al (m

V)

0

Time (min)10 128642

0

6

8

10

4

2

51

3

4

s

(b)

Time (min)10 128642

s

1

2

3

4

Sign

al (m

V)

0

6

8

10

4

25

(c)

Time (min)108642

s

1

2

3

4

Sign

al (m

V)

5

6

8

10

9

7

(d)









Sign

al (m

V)

Time (min)10 128642

6

8

10

12

14

4

2

1

2

3

4

5

s

(a)

Time (min)10 128642

Sign

al (m

V)

8

12

16

4

1

2

3

4

5

s20

0

(b)







Time (min)10 128642

Sign

al (m

V)

6

12

15

3

9

0

1 2

3

4

5

6




iA

Inte

rnal

stand

ard


w(DADMAC) ()

20

18

16

14

12

10

08

06

6050403020100





Extr

actio

n effi

cien

cy (

)


100

80

60

40

20

0









Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167


Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173





4 Conclusions



Competing Interests


Acknowledgments



References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Time (min)

Sign

al (m

V)

10

20

30

40

50

60

0

1086420

s

(a)

Sign

al (m

V)

10

20

30

40

50

60

0

Time (min)10 1286420

s

1

2

3

4

5

(b)

Sign

al (m

V)

10

20

30

40

0

Time (min)10 128642

s

1

2

3

4 5

(c)







Sign

al (m

V)

10

20

0

Time (min)10 128642

5

15

1

2

3

4

s

(a)

Sign

al (m

V)

0

Time (min)10 128642

0

6

8

10

4

2

51

3

4

s

(b)

Time (min)10 128642

s

1

2

3

4

Sign

al (m

V)

0

6

8

10

4

25

(c)

Time (min)108642

s

1

2

3

4

Sign

al (m

V)

5

6

8

10

9

7

(d)









Sign

al (m

V)

Time (min)10 128642

6

8

10

12

14

4

2

1

2

3

4

5

s

(a)

Time (min)10 128642

Sign

al (m

V)

8

12

16

4

1

2

3

4

5

s20

0

(b)







Time (min)10 128642

Sign

al (m

V)

6

12

15

3

9

0

1 2

3

4

5

6




iA

Inte

rnal

stand

ard


w(DADMAC) ()

20

18

16

14

12

10

08

06

6050403020100





Extr

actio

n effi

cien

cy (

)


100

80

60

40

20

0









Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167


Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173





4 Conclusions



Competing Interests


Acknowledgments



References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Sign

al (m

V)

10

20

0

Time (min)10 128642

5

15

1

2

3

4

s

(a)

Sign

al (m

V)

0

Time (min)10 128642

0

6

8

10

4

2

51

3

4

s

(b)

Time (min)10 128642

s

1

2

3

4

Sign

al (m

V)

0

6

8

10

4

25

(c)

Time (min)108642

s

1

2

3

4

Sign

al (m

V)

5

6

8

10

9

7

(d)









Sign

al (m

V)

Time (min)10 128642

6

8

10

12

14

4

2

1

2

3

4

5

s

(a)

Time (min)10 128642

Sign

al (m

V)

8

12

16

4

1

2

3

4

5

s20

0

(b)







Time (min)10 128642

Sign

al (m

V)

6

12

15

3

9

0

1 2

3

4

5

6




iA

Inte

rnal

stand

ard


w(DADMAC) ()

20

18

16

14

12

10

08

06

6050403020100





Extr

actio

n effi

cien

cy (

)


100

80

60

40

20

0









Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167


Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173





4 Conclusions



Competing Interests


Acknowledgments



References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Sign

al (m

V)

Time (min)10 128642

6

8

10

12

14

4

2

1

2

3

4

5

s

(a)

Time (min)10 128642

Sign

al (m

V)

8

12

16

4

1

2

3

4

5

s20

0

(b)







Time (min)10 128642

Sign

al (m

V)

6

12

15

3

9

0

1 2

3

4

5

6




iA

Inte

rnal

stand

ard


w(DADMAC) ()

20

18

16

14

12

10

08

06

6050403020100





Extr

actio

n effi

cien

cy (

)


100

80

60

40

20

0









Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167


Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173





4 Conclusions



Competing Interests


Acknowledgments



References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


iA

Inte

rnal

stand

ard


w(DADMAC) ()

20

18

16

14

12

10

08

06

6050403020100





Extr

actio

n effi

cien

cy (

)


100

80

60

40

20

0









Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167


Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173





4 Conclusions



Competing Interests


Acknowledgments



References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Dimethylamine1075 100 2230 1075 5951912 200 3739 956 3772742 300 5621 979 167


Allyl chloride1239 100 2223 993 1621900 200 3705 950 1452680 300 5867 1033 221

Allyl alcohol1171 100 2147 989 2151624 200 3464 956 3752473 300 5342 976 197

Allyl aldehyde2488 100 3397 974 1403877 200 5695 969 2055358 300 8316 995 173





4 Conclusions



Competing Interests


Acknowledgments



References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

Quantitative Analysis of Volatile Impurities in