multicomponentreactions,solvent-freesynthesisof 2-amino-4...

Research ArticleMulticomponent Reactions Solvent-Free Synthesis of2-Amino-4-aryl-6-substituted Pyridine-35-dicarbonitrileDerivatives and Corrosion Inhibitors Evaluation

Naglaa F H Mahmoud and Ahmed El-Sewedy

Department of Chemistry Faculty of Science Ain Shams University Abbasia 11566 Cairo Egypt

Correspondence should be addressed to Naglaa F H Mahmoud naglaafawzyyahoocom

Received 9 September 2018 Revised 4 November 2018 Accepted 27 November 2018 Published 19 December 2018

Academic Editor Mohamed Afzal Pasha

Copyright copy 2018 Naglaa F H Mahmoud and Ahmed El-Sewedy is is an open access article distributed under the CreativeCommons Attribution License which permits unrestricted use distribution and reproduction in any medium provided theoriginal work is properly cited

A number of 2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrile derivatives were synthesized via one-pot multicomponentcondensation reactions of different aromatic aldehydes with malononitrile and different primary amines using different mo-lecular ratios and different reaction conditions to achieve considerable product yields Moreover we succeed for the first time todevelop a newmethod to synthesize the aforementioned under the fusion condition without using solvent and catalysts With thismethod a wide range of novel 2-amino-35-dicyano-4-aryl-6-substituted aminopyridine derivatives were synthesized with highyields and board substrate of functional groups e synthesized pyridine derivatives were found to have a corrosion inhibitionefficiency the rate of which increased with the increasing concentration of the derivatives e structures of the new compoundswere elucidated by spectroscopic data and elemental analyses

1 Introduction

Multicomponent reactions (MCRs) have drawn high effortsin recent years owing to exceptional synthetic efficiencyhigh selectivity and procedural simplicity [1ndash6] One-potmulticomponent reactions are a new method to constructheterocyclic compounds with bond making andor bondbreaking in one step with high atom economy and thediversity can be achieved by varying the reacting compo-nents A large number of organic reactions which werecarried out afforded higher yields shorter reaction time andmilder conditions [7ndash9]

Substituted pyridines were used as medical scaffoldsbecause they are part of many natural product structures[10 11] Pyridine derivatives have also showed a broadspectrum of biological activities such as antimitotic agents[12] anti-inflammatory substances [13] and anticonvulsants[14] In addition they also regulate arterial pressure [15] andcholesterol level in blood [16] Furthermore they wereutilized as electrical materials [17] and chelating agents [18]

Furthermore organic compounds rich in heteroatoms be-have as corrosion inhibitors when they are absorbed in themetal surface to form a protective layer preventing cathodicandor anodic reactions and forming a compact barrier film[19ndash21]

From the synthetic aspect most of the existing studies on2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrilederivatives [22] were synthesized by ZnCl2-catalyzed mul-tistep methods [23] and one-pot multicomponent reactions[24] with good yield

e addition of corrosion inhibitors is a useful approachto protect mild steel (MS) surfaces from corrosion damage[25] Considerable efforts are made to synthesize new or-ganic molecules offering various molecular structures emost synthesized compounds are the nitrogen-heterocycliccompounds which are known to be excellent complex orchelate-forming substances with metals of transition series[26] Also the heterocyclic compounds containing nitrogenatoms can be easily protonated in the acidic medium toexhibit good inhibitory action [27]

HindawiJournal of ChemistryVolume 2018 Article ID 7958739 9 pageshttpsdoiorg10115520187958739

In our preliminary studies we have investigated the one-pot multicomponent reactions of different aromatic alde-hydes with malononitrile and primary amines using variousLewis acids such as ZnCl2 AlCl3 and FeCl3 in ethanol as asolvent with different molecular ratios e pyridine de-rivatives were obtained in good yield using solvent andcatalyst-free condition under the fusion condition Ami-nopyridine derivatives and their corrosion inhibitionproperties were evaluated by weight loss measurements ofsteel with different concentrations of inhibitors

2 Results and Discussion

21 Chemistry According to literature [22] 2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrile derivativeswere synthesized by a multistep pathway in the presence ofZnCl2 only as the catalyst at 75degC with 81 yield

In our present study we have investigated the one-potmulticomponent reactions (MCRs) to prepare amino-pyridine derivatives 1ndash20 using different Lewis acid catalystssuch as ZnCl2 AlCl3 and FeCl3 using a molar ratio of 1 2 3(aromatic aldehydes malononitrile primary amines) wherethe desired products were obtained in moderate yields

e first trial was performed using one equivalent ofaromatic aldehydes two equivalents of malononitrile andone equivalent of primary amines in the presence of ZnO(nano particles) CAN NaOEt andor H3PO4 as catalysts inrefluxing ethanol for 12 h and no products were observedeven after changing the molar ratio of amines to twoequivalents andor three equivalents (Table 1 entries 1ndash12)(Scheme 1)

e second trial was carried out using ethanolic solu-tions of aromatic aldehydes malononitrile and primaryamines in the presence of Lewis acids as catalysts such asAlCl3 ZnCl2 and FeCl3 e reaction mixture was refluxedfor 6 h using different molar ratios 1 2 1 1 2 2 and 1 2 3(aromatic aldehydes malononitrile primary amines) re-spectively e desired products were obtained with themolar ratios of 1 2 3 in moderate yields (Table 1 entries13ndash21)

As initial endeavor the reaction was performed witharomatic aldehydes (1 equivalent) malononitrile (2 equiv-alents) and primary amines (1 equivalent) by fusion solventand catalyst-free condition and a solid precipitate of dif-ferent 2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrile derivatives 1ndash20 were separated out withhigh yields (Table 1 entry 22) (Scheme 2)

e formation of the desired products 1ndash20 could beexplained via the formation of the arylidene molecule thanthe Michael addition of malononitrile on the double bond ofthe arylidene moiety forming the intermediate which un-derwent cyclization by the nucleophilic attack of amine onthe cyanocarbon followed by aromatization to the finalproducts 1ndash20 (Scheme 3)

As a conclusion we have developed for the first time asolvent-free one-pot multicomponent reaction withoutusing any catalysts With this method a wide range of novel2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrilederivatives were synthesized in high yields with a board

substrate of functional groups ose derivatives aredepicted in Scheme 4

22 Evaluation of the Synthesized 2-Amino-4-aryl-6-substituted Pyridine-35-dicarbonitrile as CorrosionInhibitors Alloys are exceedingly applied in manufactureprocessing applications and might undergo various acidicmediums Acids were aggressive on the metal surface andprogress to serious corrosion issues Corrosion has beencontrolled by employing natural or synthetic inhibitorsMost of the utilizing inhibitors were from organic moleculeswith heteroatoms such as nitrogen sulphur phosphorusand oxygen in addition to double bonds or aromatic rings intheir structure that adsorbed on the surface of the metalsCorrosion inhibitors usually have the ability to control thecorrosion through forming different kinds of films in variousroutes such as adsorption through formation of precipitatesor through forming of the inactive layer on the surface of themetal Several organic inhibitors impeded the corrosionprocess by forming the invisible thin film on the metalsurface

e corrosion inhibition tendency of the synthesized 2-amino-35-dicyano-4-aryl-6-substituted aminopyridine de-rivatives was tested by studying the weight loss of steelcoupons immersed in a solution of 6MHCl for nine daytimeintervals of immersion at room temperature e weight loss(gravimetric method) is known to be the most widely usedmethod of monitoring inhibition efficiency e results ofweight loss of steel coupons with the addition of differentconcentrations 200 400 and 800 ppm of different inhibitorsduring 1 3 5 7 and 9 days of immersion in 6M HCl are

Table 1 Optimization of reaction conditions

Entry Catalyst Aldehyde Malononitrile Amine Yield()

1 ZnO 15 1 2 1 mdash2 ZnO 15 1 2 2 mdash3 ZnO 15 1 2 3 mdash4 CAN 15 1 2 1 mdash5 CAN 15 1 2 2 mdash6 CAN 15 1 2 3 mdash7 NaOEt 15 1 2 1 mdash8 NaOEt 15 1 2 2 mdash9 NaOEt 15 1 2 3 mdash10 H3PO4 15 1 2 3 mdash11 H3PO4 15 1 2 3 mdash12 H3PO4 15 1 2 3 mdash13 AlCl3 15 1 2 1 mdash14 AlCl3 15 1 2 2 mdash15 AlCl3 15 1 2 3 2516 ZnCl2 15 1 2 1 mdash17 ZnCl2 15 1 2 2 mdash18 ZnCl2 15 1 2 3 4519 FeCl3 15 1 2 1 mdash20 FeCl3 15 1 2 2 mdash21 FeCl3 15 1 2 3 37

22 Neatreaction 0 1 2 1 90

CAN ceric ammonium nitrate

2 Journal of Chemistry

showed in Table 2 [28ndash31] e corrosion rate (k) the in-hibition efficiencies (ηw) and the degree of surface coverage(θ) were calculated from the following equations

θ Wo minusW( 1113857

Wo (1)

ηW Wo minusW( 1113857

Wo1113888 1113889 times 100 (2)

k W

St (3)

where S is the total area of the specimen t is the immersiontime and Wo and W are the values of the weight loss in theabsence andor presence of different concentrations of theinhibitors Data in Table 2 and Figures 1ndash3 show that the

synthesized 2-amino-35-dicyano-4-aryl-6-substitutedaminopyridine derivatives 1 5 6 and 8 protected steelfrom corrosion e weight loss decreases and inhibitionefficiency increases in the presence of inhibitors As aresult of weigh loss of mild steel in 6M HCl with andwithout addition of various concentration of 2-amino-35-dicyano-4-aryl-6-substituted aminopyridine de-rivatives e efficiency increase with increasing theconcentration of the inhibitor which elucidated that thenumber of molecules adsorbed increased over the steelblocking the active sites from acid and protecting the steelfrom corrosion At 800 ppm which is the highest con-centration also the best inhibition achievement of thederivative 5 was impute to presence of two methoxygroups attached to the phenyl ese electron groupsincrease the resonance capability toward conjugationsowing to the presence of unshared electron pairs on the

X

X=H OCH3 Cl and PhCH=CH

CHOCN CatalystEtOH

X

NC

NC

N

NH2

HN R1ndash20

Reflux

R=aryl alkyl

+ +

CN

H2N R

Scheme 1

X


CHOCN

X

NC

NC

N

NH2

1ndash20

Fusion

R=aryl alkyl

+ +CN

H2N R

HN R

Scheme 2

ndashX

X

1ndash20

XCHO

NC

NC

NH NH2

Aromatization

NC

NC

ndashH2

NH2NH2

X

X

NC NC

NC NC

NCNC

NCNC

C

C

C C C

CC H

X

C

C

N

N

NH

NH

NH

C N

H2N R

HN RHN R

HN R

+

HN R

Scheme 3

Journal of Chemistry 3

nitrogen and oxygen atoms and thus increase the in-hibition performance

3 Experimental Section

All melting points measured on a Gallenkamp electricmelting point apparatus are uncorrected e infraredspectra were recorded in potassium bromide disks on a pyeUnicam SP-3-300 and Shimdzu FT IR 8101 PC infraredspectrophotometers at the central laboratory of faculty ofscience Ain Shams University

e 1H-NMR spectra were recorded on a Varian Mer-cury VX-300MHz using TMS as an internal standard in

deuterated dimethylsulphoxide (DMSO-d6) Chemical shiftsare measured in ppm e mass spectra were recorded on aShimadzu GCMS-QP-1000EX mass spectrometer At 70 eVelemental analyses were carried out at the microanalyticalcenter of Ain Shams University All the reactions and thepurity of the new compounds were monitored by TLC usingTLC aluminum sheets silica gel F254

31 Chemistry General method for synthesis of 2-amino-4-aryl-6-substituted pyridine-35-dicarbonitriles 1ndash20 is asfollows

(a) One-pot multicomponent reactions by fusion

(19) 84

NC

NC NH

N

NH2

(16) 81

NC

NC HN

N

NH2

OCH3

(13) 88

NC

Cl

NC HN

N

NH2

NO2

(10) 76

(7) 82

NC

O

ONC HN

N

NH2

NC

O

COOHNC HN

N

NH2

(4) 95

NC

NC HN

N

NH2

(1) 90

NC

NC HN

N

NH2

(20) 82

NC

NC NH

HO

N

NH2

(17) 73

NC

NC HN

N

NH2

NO2

(14) 90

NC

Cl

NC HN

N

NH2

(11) 91

(8) 79

NC

Cl

NC HN

N

NH2

NC

O

HOOC

NC HN

N

NH2

(5) 89

NC

O

ONC HN

N

NH2

(2) 91

NC

NC HN

N

NH2

(18) 88

NC

NC NH

N

NH2

(15) 78

NC

NC HN

N

NH2

(12) 92

(9) 84

NC

Cl

NC HN O

NH2

N

NC

O

HO

NC HN

N

NH2

(6) 87

NC

O

NC HN

N

NH2

(3) 93

NC

NC NH2

N

NH2

Scheme 4


Tabl

e2

Corrosio

nratesurface

covering

and

corrosioninhibitio

neffi

ciency

of1

56

and8inhibitors

atroom

temperature

No

Dose(ppm

)1day

3days

5days

7days

9days

K(m

gmiddotcmminus2 hminus1 )

θη(

)K(m


θη(

)K(m


(θ)

η(

)K(m


θη(

)K(m


θη(

)Blank

0001590

mdashmdash

0001404

mdashmdash

0001484

mdashmdash

000171

mdashmdash

0001968

mdashmdash

1200

0001267

0203

203

0001029

02665

2665

0001046

02949

2949

000116

03168

3168

0001202

03891

3891

400

0001059

03337

3337

0000876

03755

3755

0000886

04027

4027

0000911

04673

4673

0000922

05316

5316

800

000090

04321

4321

0000750

04657

4657

0000732

05068

5068

0000705

05874

5874

0000704

06421

6421

5200

0001057

03350

3350

0000832

04072

4072

0000842

04327

4327

0000873

04892

4892

0000850

05678

5678

400

0001010

03642

3642

0000794

04341

4341

0000795

04642

4642

0000839

05089

5089

0000806

05902

5902

800

0000832

04767

4767

0000617

05601

5601

0000607

05910

5910

0000582

06594

6594

0000569

07104

7104

6200

0001148

02779

2779

0000983

02997

2997

0001000

03261

3261

0001100

03564

3564

0001097

04423

4423

400

0001021

03576

3576

0000801

0429

429

0000793

04654

4654

0000895

04762

4762

0000911

05369

5369

800

0000939

04092

4092

0000781

04432

4432

0000752

04929

4929

0000735

05697

5697

0000748

06199

6199

8200

0001149

02772

2772

0000979

03021

3021

0001021

03120

3120

0001153

03254

3254

0001169

04060

4060

400

000104

03415

3415

0000800

04296

4296

0000776

04771

4771

0000846

05048

5048

0000871

05573

5573

800

0000940

04083

4083

0000767

04532

4532

0000686

05374

5374

0000653

06181

6181

0000654

06675

6674


In a round bottom flask aromatic aldehydes (001mol)malononitrile (002mol) and different primary amines(001mol) were fused in sand bath for 3 h at 140ndash200degCAfter cooling the products were recrystallized from theproper solvent to give 1ndash20

(b) One-pot multicomponent reactions using AlCl3ZnCl2 andor FeCl3 as a catalyst

Mixture of aromatic aldehydes (001mol) malononitrile(002mol) primary amines (003mol) and catalyst(0015mol) was refluxed in ethanol (20mL) for 6h ereaction mixture was poured onto icewater and the sep-arated products were washed dried and recrystallized fromthe proper solvent to afford compounds (1ndash20)

311 2-Amino-4-phenyl-6-(phenylamino)pyridine-35-dicarbonitrile (1) Yield (90) yellow powder m p 250ndash252degC (ethanol) FT-IR (KBr) (cmminus1) 3314 3225 (NH2) 3155

(NH) 2208 (CN) and 1630 (CN) 1H-NMR (DMSO-d6) δ(ppm) 910 (brs 1H NH D2O exchangeable) 764 (brs 2HNH2 D2O exchangeable) and 756ndash705 (m 10H ArH) MSmz (311) Anal calcd for C19H13N5 (311) C 7330 H 421and N 2249 Found C 7336 H 417 and N 2252

312 2-Amino-4-phenyl-6-(p-tolylamino)pyridine-35-dicarbonitrile (2) Yield (91) yellow powder m p 258ndash260degC (ethanol) FT-IR (KBr) (cmminus1) 3310 3215 (NH2) 3158(NH) 2208 (CN) and 1630 (CN) 1H-NMR (DMSO-d6) δ(ppm) 902 (brs 1H NH D2O exchangeable) 754ndash709 (m9H ArH) 749 (brs 2H NH2 D2O exchangeable) and 226(s 3H CH3) MSmz (325) Anal calcd for C20H15N5 (325)C 7383 H 465 and N 2152 Found C 7388 H 460 andN 2148

313 26-Diamino-4-phenylpyridine-35-dicarbonitrile (3)Yield (93) yellow powder m p 292ndash293degC (ethanol) FT-IR (KBr) (cmminus1) 3424 3363 (NH2) 3218 3155(NH2) 2206(CN) and 1623 (CN) 1H-NMR (DMSO-d6) δ (ppm)752ndash743 (m 5H ArH) and 723 (brs 4H NH2 D2O ex-changeable) MS mz (235) Anal calcd for C13H9N5 (235)C 6637 H 386 and N 2977 Found C 6641 H 381 andN 2971

314 2-Amino-6-(ethylamino)-4-phenylpyridine-35-dicarbonitrile (4) Yield (95) yellow powder m p 226ndash228degC (ethanol) FT-IR (KBr) (cmminus1) 3323 3218 (NH2) 3168(NH) 2225 (CN) and 1623 (CN) 1H-NMR (DMSO-d6) δ(ppm) 792 (brs 1H NH D2O exchangeable) 754ndash743 (m5H ArH) 723 (brs 2H NH2 D2O exchangeable) 332 (q2H CH2) and 110 (t 3H CH3) MSmz (263) Anal calcdfor C15H13N5 (263) C 6842 H 498 and N 2660 FoundC 6847 H 492 and N 2656

202224262830323436384042444648505254565860

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)

Time (h)

15

68

Figure 1 Relation between inhibition efficiency of aminopyridinederivatives in 6M HCl and time at room temperature at 200 ppm

Time (h)

15

68

303234363840424446485052545658606264

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

η (

)


Time (h)

15

68

38404244464850525456586062646668707274767880

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)



315 2-Amino-4-(4-methoxyphenyl)-6-((4-methoxyphenyl)amino)pyridine-35-dicarbonitrile (5) Yield (89) brownpowder m p 256ndash258degC (acetone) FT-IR (KBr) (cmminus1)3299 3199 (NH2) 3124 (NH) 2209 (CN) and 1606 (CN)1H-NMR (DMSO-d6) δ (ppm) 917 (brs 1H NH D2Oexchangeable) 749ndash676 (m 8H ArH) 432 (brs 2H NH2D2O exchangeable) 386 (s 3H OCH3) and 383 (s 3HOCH3) MSmz (371) Anal calcd for C21H17N5O2 (371) C6791 H 461 and N 1886 Found C 6795 H 455 and N1881

316 2-Amino-4-(4-methoxyphenyl)-6-(p-tolylamino)pyridine-35-dicarbonitrile (6) Yield (87) brown pow-der m p 268ndash270degC (acetone) FT-IR (KBr) (cmminus1) 33043202 (NH2) 3128 (NH) 2211 (CN) and 1607 (CN) 1H-NMR (DMSO-d6) δ (ppm) 910 (brs 1H NH D2O ex-changeable) 752ndash702 (m 8H ArH) 689 (brs 2H NH2D2O exchangeable) 388 (s 3H OCH3) and 230 (s 3HCH3) MS mz (355) Anal calcd for C21H17N5O (355) C7097 H 482 and N 1971 Found C 7104 H 478 and N1966

317 4-((6-Amino-35-dicyano-4-(4-methoxyphenyl)pyridin-2-yl)amino)benzoic Acid (7) Yield (82) brown powderm p over 300degC (acetone) FT-IR (KBr) (cmminus1) broad bandcentered at 3326 (OH NH2) 3195 (NH) 2212 (CN) 1732(CO) and 1630 (CN) 1H-NMR (DMSO-d6) δ (ppm)1040 (brs 1H OH D2O exchangeable) 910 (brs 1HNH D2O exchangeable) 806ndash718 (m 8H ArH) 667(brs 2H NH2 D2O exchangeable) and 389 (s 3HOCH3) MS mz (385) Anal calcd for C21H15N5O3 (385)C 6545 H 392 and N 1817 Found C 6549 H 387and N 1813

318 2-((6-Amino-35-dicyano-4-(4-methoxyphenyl)pyridin-2-yl)amino)benzoic Acid (8) Yield (79) brown powderm p over 300degC (acetone) FT-IR (KBr) (cmminus1) broad bandcentered at 3341 (OH NH2) 3219 (NH) 2208 (CN) 1735(CO) and 1630 (CN) 1H-NMR (DMSO-d6) δ (ppm)1104 (brs 1H OH D2O exchangeable) 999 (brs 1H NHD2O exchangeable) 776ndash707 (m 8H ArH) 385 (s 3HOCH3) and 697 (brs 2H NH2 D2O exchangeable) MSmz (385) Anal calcd for C21H15N5O3 (385) C 6545 H 392and N 1817 Found C 6550 H 396 and N 1821

319 2-Amino-6-((2-hydroxyphenyl)amino)-4-(4-methoxyphenyl)pyridine-35-dicarbonitrile (9) Yield (84) black powderm p over 300degC (acetone) FT-IR (KBr) (cmminus1) 3424 (OH)3373 3286 (NH2) 3219 (NH) 2206 (CN) and 1630 (CN)1H-NMR (DMSO-d6) δ (ppm) 1008 (brs 1H OH D2Oexchangeable) 994 (brs 1H NH D2O exchangeable)685ndash771 (m 8H ArH) 683 (brs 2H NH2 D2O ex-changeable) and 381 (s 3H OCH3) MS mz (357) Analcalcd for C20H15N5O2 (357) C 6722 H 423 and N 1960Found C 6728 H 418 and N 1956

3110 2-((4-Acetylphenyl)amino)-6-amino-4-(4-methoxyphenyl)pyridine-35-dicarbonitrile (10) Yield (76) brown powderm p over 300degC (acetone) FT-IR (KBr) (cmminus1) 3326 3232(NH2) 3195 (NH) 2209 (CN) 1698 (CO) and 1630 (CN)1H-NMR (DMSO-d6) δ (ppm) 993 (brs 1H NH D2Oexchangeable) 789ndash702 (m 8H ArH) 689 (brs 2H NH2D2O exchangeable) 383 (s 3H -OCH3) and 253 (s 3HCH3) MS mz (383) Anal calcd for C22H17N5O2 (383) C6892 H 447 and N 1827 Found C 6897 H 443 and N1821

3111 2-Amino-4-(4-chlorophenyl)-6-(phenylamino)pyridine-35-dicarbonitrile (11) Yield (91) brown powder m pover 300degC (acetone) FT-IR (KBr) (cmminus1) 3416 3303 (NH2)3215 (NH) 2209 (CN) and 1621 (CN) 1H-NMR (DMSO-d6) δ (ppm) 993 (brs 1H NH D2O exchangeable)778ndash702 (m 9H ArH) and 689 (brs 2H NH2 D2Oexchangeable) MS mz (345) Anal calcd for C19H12ClN5(345) C 6600 H 350 and N 2025 Found C 6604 H346 and N 2021

3112 2-Amino-4-(4-chlorophenyl)-6-(4-methoxyphenyl)amino)pyridine-35-dicarbonitrile (12) Yield (92) brownpowder m p over 300degC (acetone) FT-IR (KBr) (cmminus1)3325 3222 (NH2) 3158 (NH) 2207 (CN) and 1629 (CN)1H-NMR (DMSO-d6) δ (ppm) 919 (brs 1H NH D2Oexchangeable) 765ndash679 (m 8H ArH) 692 (brs 2H NH2D2O exchangeable) and 383 (s 3H OCH3) MSmz (375)Anal calcd for C20H14ClN5O (3751) C 6392 H 376 andN 1864 Found C 6398 H 371 and N 1858

3113 2-Amino-4-(4-chlorophenyl)-6-((4-nitrophenyl)amino)pyridine-35-dicarbonitrile (13) Yield (88) black powderm p over 300degC (acetone) FT-IR (KBr) (cmminus1) 3322 3227(NH2) 3128(NH) 2209 (CN) and 1623 (CN) 1H-NMR(DMSO-d6) δ (ppm) 910 (brs 1H NH D2O exchangeable)801ndash706 (m 8H ArH) and 778 (brs 2H NH2 D2Oexchangeable) MSmz (390) Anal calcd for C19H11ClN6O2(390) C 5840 H 284 and N 2151 Found C 5835 H279 and N 2145

3114 2-Amino-4-(4-chlorophenyl)-6-(p-tolylamino)pyridine-35-dicarbonitrile (14) Yield (90) yellow powder m pover 200ndash202degC (acetone) FT-IR (KBr) (cmminus1) 3285 3238(NH2) 3137 (NH) 2207 (CN) and 1613 (CN) 1H-NMR(DMSO-d6) δ (ppm) 745 (brs 1H NH D2O exchangeable)682ndash640 (m 8H ArH) 465 (brs 2H NH2 D2O ex-changeable) and 230 (s 3H CH3) MS mz (359) Analcalcd for C20H14ClN5 (359) C 6676 H 392 and N 1946Found C 6671 H 397 and N 1953

3115 2-Amino-6-(phenylamino)-4-styrylpyridine-35-dicarbonitrile(15) Yield (78) black powder m p over 300degC (acetone)FT-IR (KBr) (cmminus1) 3372 3265 (NH2) 3160 (NH) 2202(CN) and 1626 (CN) 1H-NMR (DMSO-d6) δ (ppm) 1013(brs 1H NH D2O exchangeable) 750ndash697 (m 10H


ArH) 724 (d 1H CH) 699 (d 1H CH) and 695 (brs2H NH2 D2O exchangeable) MS mz (337) Anal calcdfor C21H15N5 (337) C 7476 H 448 and N 2076 FoundC 7472 H 452 and N 2081

3116 2-Amino-6-((4-methoxyphenyl)amino)-4-styrylpyridine-35-dicarbonitrile (16) Yield (81) black powder m p over300degC (acetone) FT-IR (KBr) (cmminus1) 3354 3207 (NH2) 3118(NH) 2206 (CN) and 1613 (CN) 1H-NMR (DMSO-d6) δ(ppm) 1013 (brs 1H NH D2O exchangeable) 763ndash704 (m9H ArH) 724 (d 1H CH) 699 (d 1H CH) 695 (brs2H NH2 D2O exchangeable) and 383 (s 3H OCH3)MSmz (367) Anal calcd for C22H17N5O (367) C 7192 H 466and N 1906 Found C 7198 H 461 and N 1898

3117 2-Amino-6-((4-nitrophenyl)amino)-4-styrylpyridine-35-dicarbonitrile (17) Yield (73) black powder m pover 300degC (acetone) FT-IR (KBr) (cmminus1) 3344 3215(NH2)3120 (NH) 2203 (CN) and 1606 (CN) 1H-NMR (DMSO-d6) δ (ppm) 1013 (brs 1H NH D2O exchangeable) 689(brs 2H NH2 D2O exchangeable) 763ndash704 (m 9H ArH)721 (d 1H CH) and 696 (d 1H CH) MS mz (382)Anal calcd for C21H14N6O2 (382) C 6596 H 369 and N2198 Found C 6591 H 374 and N 2203

3118 2-Amino-6-(ethylamino)-4-styrylpyridine-35-dicarbonitrile(18) Yield (88) black powder m p over 300degC (acetone)FT-IR (KBr) (cmminus1) broad band at 3346 (NH2 NH) 2203(CN) and 1614 (CN) 1H-NMR (DMSO-d6) δ (ppm)786ndash736 (m 5H ArH) 780 (brs 1H NH D2O ex-changeable) 725 (d 1H CH) 677 (brs 2H NH2 D2Oexchangeable) 646 (d 1H CH) 364 (q 2H CH2) and110 (t 3H CH3) MS mz (289) Anal calcd for C17H15N5(289) C 7057 H 523 and N 2420 Found C 7053 H529 and N 2425

3119 2-Amino-6-(benzylamino)-4-styrylpyridine-35-dicarbonitrile(19) Yield (84) black powder m p over 300degC (acetone)FT-IR (KBr) (cmminus1) 3364 3262 (NH2) 3060 (NH) 2203(CN) and 1612 (CN) 1H-NMR (DMSO-d6) δ (ppm) 883(brs 1H NH D2O exchangeable) 415 (s 2H NHCH2)689 (brs 2H NH2 D2O exchangeable) 760ndash744 (m 10HArH) 720 (d 1H CH) and 693 (d 1H CH) MS mz(351) Anal calcd for C22H17N5 (351) C 7519 H 488 andN 1993 Found C 7526 H 482 and N 1986

3120 2-Amino-6-((2-hydroxyethyl)amino)-4-styrylpyridine-35-dicarbonitrile (20) Yield (82) black powder m pover 300degC (acetone) FT-IR (KBr) (cmminus1) broad bandcentered at 3335 (OH NH2 NH) 2207 (CN) and 1623(CN) 1H-NMR (DMSO-d6) δ (ppm) 883 (brs 1H NHD2O exchangeable) 760ndash730 (m 5H ArH) 720 (d 1HCH) 693 (d 1H CH) 689 (brs 2H NH2 D2O ex-changeable) 455 (brs 1H OH D2O exchangeable) 360 (t2H CH2CH2OH) and 315 (t 2H NHCH2CH2) MS mz

(305) Anal calcd for C17H15N5O (305) C 6687 H 495and N 2294 Found C 6697 H 489 and N 2286

32 Experimental for Corrosion Coupons of steel were cutinto 1 times 1 times 05 cm3 dimensions are used for the gravimetricmethod e specimens are washed dried and weighteden coupons were immersed in a beaker containing 50mlof a solution of 6M HCl for 9 days with different concen-trations of the synthesized 2-amino-35-dicyano-4-aryl-6-substituted aminopyridine derivatives e specimens werewashed dried and reweighted to take the difference inweight of steel coupons with and without the inhibitorscorrosion rate (CR) inhibition efficiencies (η ()) and thedegree of surface coverage (θ) for different concentrations atroom temperature

4 Conclusion

In summary we have developed for the first time one-potmulticomponent reaction under the fusion condition withoutusing solvent and catalysts With this method a wide range ofnovel 2-amino-35-dicyano-4-aryl-6-substituted amino-pyridine derivatives were synthesized in high yields with aboard substrate of functional groups e synthesized pyri-dine derivatives act as corrosion inhibitors and the rate ofinhibition efficiency increases with the increasing concen-tration of the inhibitor

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that there are no conflicts of interest

Acknowledgments

e authors would like to express their appreciation for AinShams University

References

[1] J Zhu and H BienaymeMulticomponent Reactions ReviewsWiley VCH Weinheim Germany 2005

[2] A Domling ldquoRecent developments in isocyanide basedmulticomponent reactions in applied chemistrydaggerrdquo ChemicalReviews vol 106 no 1 pp 17ndash89 2006

[3] D J Ramon M Yus and M Angew ldquoAsymmetric multi-component reactions (AMCRs) the new frontierrdquo Ange-wandte Chemie International Edition vol 44 no 11pp 1602ndash1634 2005

[4] C l Simon T Constantieux and J Rodriguez ldquoUtilisation of13-dicarbonyl derivatives in multicomponent reactionsrdquoEuropean Journal of Organic Chemistry vol 2004 no 24pp 4957ndash4980 2004

[5] H Bienaym C Hulme G Oddon and P Schmitt ldquoMaxi-mizing synthetic efficiency multi-component trans-formations lead the wayrdquo Chemistry A European Journalvol 6 no 18 pp 3321ndash3329 2000


[6] A Ulaczyk-Lesanko and D G Hall ldquoWanted new multi-component reactions for generating libraries of polycyclicnatural productsrdquo Current Opinion in Chemical Biologyvol 9 no 3 pp 266ndash276 2005

[7] H Lebel and V Paquet ldquoHighly chemoselective rhodium-catalyzed methylenation of fluorine-containing ketonesrdquoOrganic Letters vol 4 pp 1671ndash1674 2002

[8] M-Y Lin S J Maddirala and R-S Liu ldquoSolvent-dependentchemoselectivity in ruthenium-catalyzed cyclization ofIodoalkyneminusEpoxide functionalitiesrdquo Organic Letters vol 7pp 1745ndash1748 2005

[9] X Wang X-P Xu S-Y Wang W Zhou and S-J Ji ldquoHighlyefficient chemoselective synthesis of polysubstituted pyrrolesvia isocyanide-based multicomponent domino reactionrdquoOrganic Letters vol 15 pp 4246ndash4249 2013

[10] P E Alford G W Gribble and J A Joule ldquoSix-memberedring systems pyridines and benzo derivativesrdquo Progress inHeterocyclic Chemistry vol 22 pp 349ndash391 2011

[11] T Kubota T Nishi E Fukushi J Kawabata J Fromont andJ Kobayashi ldquoNakinadine A a novel bis-pyridine alkaloidwith a β-amino acid moiety from sponge Amphimedon sprdquoTetrahedron Letters vol 48 no 29 pp 4983ndash4985 2007

[12] C Temple Jr G A Rener W R Waud and P E NokerldquoAntimitotic agents structure-activity studies with somepyridine derivativesrdquo Journal of Medicinal Chemistry vol 35pp 3686ndash3690 1992

[13] X-F Wang E Ohkoshi S-B Wang et al ldquoSynthesis andbiological evaluation of N-alkyl-N-(4-methoxyphenyl)pyridin-2-amines as a new class of tubulin polymerizationinhibitorsrdquo Bioorganic and Medicinal Chemistry vol 21pp 632ndash642 2013

[14] N Siddiqui W Ahsan M S Alam R Ali and K SrivastavaldquoDesign synthesis and evaluation of anticonvulsant activity ofpyridinyl-pyrrolidones a pharmacophore hybrid approachsynthesis and evaluation of anticonvulsant activity of pyr-idinyl-pyrrolidones a pharmacophore hybrid approachrdquoArchiv der Pharmazie vol 345 pp 185ndash194 2011

[15] J Mercier M Gavend V Van Luv and S Dessaigne ldquoManuelde pharmacologie a lrsquousage des eleves infirmieresrdquo CongrUnion er Int [C R] vol 8 p 361 1963

[16] G Dorner and F W Fischer ldquoSome biochemical andpharmacological properties of anti-inflammatory drugsrdquoArzneimittel Forschung vol 11 p 110 1961

[17] H Wang R Helgeson B Ma and F Wudl ldquoSynthesis andoptical properties of cross-conjugated bis(dimethylamino-phenyl)pyridylvinylene derivativesrdquo Journal of OrganicChemistry vol 65 no 18 pp 5862ndash5867 2000

[18] T Kanbara T Kushida N Saito I Kuwajima K Kubota andT Yamamoto ldquoPreparation and properties of highly electron-accepting poly(pyrimidine-25-diyl)rdquo Chemistry Lettersvol 21 no 4 pp 583ndash586 1992

[19] M T Saeed ldquoCorrosion inhibition of carbon steel in sulfuricacid by bicyclic isoxazolidinesrdquo Anti-Corrosion Methods andMaterials vol 51 no 6 pp 389ndash398 2004

[20] L-G Qiu A-J Xie and Y-H Shen ldquoe adsorption andcorrosion inhibition of some cationic gemini surfactants oncarbon steel surface in hydrochloric acidrdquo Corrosion Sciencevol 47 no 1 pp 273ndash278 2005

[21] S Muralidharan M A Quraishi and S V K Iyer ldquoe effectof molecular structure on hydrogen permeation and thecorrosion inhibition of mild steel in acidic solutionsrdquo Cor-rosion Science vol 37 no 11 pp 1739ndash1750 1995

[22] J Huang J Zhou S Song H Song Z Chen and W Yi ldquoAnew and efficient ZnCl2-catalyzed synthesis and biological

evaluation of novel 2-amino-35-dicyano-4-aryl-6-aryl-aminopyridines as potent antibacterial agents against Heli-cobacter pylori (HP)rdquo Tetrahedron vol 71 no 45pp 8628ndash8636 2015

[23] S Sarkar D K Das and A T Khan ldquoSynthesis of fully-substituted pyridines and dihydropyridines in a highly che-moselective manner utilizing a multicomponent reaction(MCR) strategyrdquo RSC Advances vol 4 no 96 pp 53752ndash53760 2014

[24] S Baghery M A Zolfigol and F Maleki ldquo[TEATNM] and[TEATCM] as novel catalysts for the synthesis of pyridine-35-dicarbonitriles via anomeric-based oxidationrdquo NewJournal of Chemistry vol 41 no 17 pp 9276ndash9290 2017

[25] M A Chidiebere E E Oguzie L Liu Y Li and F WangldquoCorrosion inhibition of Q235 mild steel in 05 M H2SO4solution by phytic acid and synergistic iodide additivesrdquoIndustrial and Engineering Chemistry Research vol 53 no 18pp 7670ndash7679 2014

[26] M Bouklah A Attayibat B Hammouti A Ramdani S Radiand M Benkaddour ldquoPyridine-pyrazole compound as in-hibitor for steel in 1M HClrdquo Applied Surface Science vol 240no 1ndash4 pp 341ndash348 2005

[27] A Ghazoui R Saddik and N Benchat etal ldquoe role of 3-amino2-phenylimidazol[12-a]pyridine as corrosion inhibitorfor C38 steel in 1M HClrdquo Der Pharma Chemica vol 4 no 1pp 352ndash364 2012

[28] M A Hegazy and F M Atlam ldquoree novel bolaamphiphilesas corrosion inhibitors for carbon steel in hydrochloric acidexperimental and computational studiesrdquo Journal of Molec-ular Liquids vol 218 pp 649ndash662 2016

[29] M A Hegazy A S El-Tabei A H Bedairb andM A SadeqbldquoSynthesis and inhibitive performance of novel cationic andgemini surfactants on carbon steel corrosion in 05 M H2SO4solutionrdquo RSC Advances vol 5 no 79 pp 64633ndash646502015

[30] M M Hemdan S M Taha A M Gabr and M Y ElkadyldquoSynthesis of some new phthalazines and their evaluation ascorrosion inhibitors of steelrdquo journal of Chemical Researchvol 38 no 10 pp 617ndash621 2014

[31] S B Al-Baghdadi F G Hashim A Q Salam et al ldquoSynthesisand corrosion inhibition application of NATN on mild steelsurface in acidic media complemented with DFT studiesrdquoResults in Physics vol 8 pp 1178ndash1184 2018


TribologyAdvances in

Hindawiwwwhindawicom Volume 2018


International Journal ofInternational Journal ofPhotoenergy


Journal of

Chemistry


Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of


NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of



Biochemistry Research International


Enzyme Research


Journal of

SpectroscopyAnalytical ChemistryInternational Journal of


MaterialsJournal of



BioMed Research International Electrochemistry

International Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

In our preliminary studies we have investigated the one-pot multicomponent reactions of different aromatic alde-hydes with malononitrile and primary amines using variousLewis acids such as ZnCl2 AlCl3 and FeCl3 in ethanol as asolvent with different molecular ratios e pyridine de-rivatives were obtained in good yield using solvent andcatalyst-free condition under the fusion condition Ami-nopyridine derivatives and their corrosion inhibitionproperties were evaluated by weight loss measurements ofsteel with different concentrations of inhibitors

2 Results and Discussion

21 Chemistry According to literature [22] 2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrile derivativeswere synthesized by a multistep pathway in the presence ofZnCl2 only as the catalyst at 75degC with 81 yield

In our present study we have investigated the one-potmulticomponent reactions (MCRs) to prepare amino-pyridine derivatives 1ndash20 using different Lewis acid catalystssuch as ZnCl2 AlCl3 and FeCl3 using a molar ratio of 1 2 3(aromatic aldehydes malononitrile primary amines) wherethe desired products were obtained in moderate yields

e first trial was performed using one equivalent ofaromatic aldehydes two equivalents of malononitrile andone equivalent of primary amines in the presence of ZnO(nano particles) CAN NaOEt andor H3PO4 as catalysts inrefluxing ethanol for 12 h and no products were observedeven after changing the molar ratio of amines to twoequivalents andor three equivalents (Table 1 entries 1ndash12)(Scheme 1)

e second trial was carried out using ethanolic solu-tions of aromatic aldehydes malononitrile and primaryamines in the presence of Lewis acids as catalysts such asAlCl3 ZnCl2 and FeCl3 e reaction mixture was refluxedfor 6 h using different molar ratios 1 2 1 1 2 2 and 1 2 3(aromatic aldehydes malononitrile primary amines) re-spectively e desired products were obtained with themolar ratios of 1 2 3 in moderate yields (Table 1 entries13ndash21)

As initial endeavor the reaction was performed witharomatic aldehydes (1 equivalent) malononitrile (2 equiv-alents) and primary amines (1 equivalent) by fusion solventand catalyst-free condition and a solid precipitate of dif-ferent 2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrile derivatives 1ndash20 were separated out withhigh yields (Table 1 entry 22) (Scheme 2)

e formation of the desired products 1ndash20 could beexplained via the formation of the arylidene molecule thanthe Michael addition of malononitrile on the double bond ofthe arylidene moiety forming the intermediate which un-derwent cyclization by the nucleophilic attack of amine onthe cyanocarbon followed by aromatization to the finalproducts 1ndash20 (Scheme 3)

As a conclusion we have developed for the first time asolvent-free one-pot multicomponent reaction withoutusing any catalysts With this method a wide range of novel2-amino-4-aryl-6-substituted pyridine-35-dicarbonitrilederivatives were synthesized in high yields with a board

substrate of functional groups ose derivatives aredepicted in Scheme 4

22 Evaluation of the Synthesized 2-Amino-4-aryl-6-substituted Pyridine-35-dicarbonitrile as CorrosionInhibitors Alloys are exceedingly applied in manufactureprocessing applications and might undergo various acidicmediums Acids were aggressive on the metal surface andprogress to serious corrosion issues Corrosion has beencontrolled by employing natural or synthetic inhibitorsMost of the utilizing inhibitors were from organic moleculeswith heteroatoms such as nitrogen sulphur phosphorusand oxygen in addition to double bonds or aromatic rings intheir structure that adsorbed on the surface of the metalsCorrosion inhibitors usually have the ability to control thecorrosion through forming different kinds of films in variousroutes such as adsorption through formation of precipitatesor through forming of the inactive layer on the surface of themetal Several organic inhibitors impeded the corrosionprocess by forming the invisible thin film on the metalsurface

e corrosion inhibition tendency of the synthesized 2-amino-35-dicyano-4-aryl-6-substituted aminopyridine de-rivatives was tested by studying the weight loss of steelcoupons immersed in a solution of 6MHCl for nine daytimeintervals of immersion at room temperature e weight loss(gravimetric method) is known to be the most widely usedmethod of monitoring inhibition efficiency e results ofweight loss of steel coupons with the addition of differentconcentrations 200 400 and 800 ppm of different inhibitorsduring 1 3 5 7 and 9 days of immersion in 6M HCl are

Table 1 Optimization of reaction conditions

Entry Catalyst Aldehyde Malononitrile Amine Yield()

1 ZnO 15 1 2 1 mdash2 ZnO 15 1 2 2 mdash3 ZnO 15 1 2 3 mdash4 CAN 15 1 2 1 mdash5 CAN 15 1 2 2 mdash6 CAN 15 1 2 3 mdash7 NaOEt 15 1 2 1 mdash8 NaOEt 15 1 2 2 mdash9 NaOEt 15 1 2 3 mdash10 H3PO4 15 1 2 3 mdash11 H3PO4 15 1 2 3 mdash12 H3PO4 15 1 2 3 mdash13 AlCl3 15 1 2 1 mdash14 AlCl3 15 1 2 2 mdash15 AlCl3 15 1 2 3 2516 ZnCl2 15 1 2 1 mdash17 ZnCl2 15 1 2 2 mdash18 ZnCl2 15 1 2 3 4519 FeCl3 15 1 2 1 mdash20 FeCl3 15 1 2 2 mdash21 FeCl3 15 1 2 3 37

22 Neatreaction 0 1 2 1 90

CAN ceric ammonium nitrate




Wo (1)


Wo1113888 1113889 times 100 (2)

k W

St (3)



X


CHOCN CatalystEtOH

X

NC

NC

N

NH2

HN R1ndash20

Reflux

R=aryl alkyl

+ +

CN

H2N R

Scheme 1

X


CHOCN

X

NC

NC

N

NH2

1ndash20

Fusion

R=aryl alkyl

+ +CN

H2N R

HN R

Scheme 2

ndashX

X

1ndash20

XCHO

NC

NC

NH NH2

Aromatization

NC

NC

ndashH2

NH2NH2

X

X

NC NC

NC NC

NCNC

NCNC

C

C

C C C

CC H

X

C

C

N

N

NH

NH

NH

C N

H2N R

HN RHN R

HN R

+

HN R

Scheme 3









(19) 84

NC

NC NH

N

NH2

(16) 81

NC

NC HN

N

NH2

OCH3

(13) 88

NC

Cl

NC HN

N

NH2

NO2

(10) 76

(7) 82

NC

O

ONC HN

N

NH2

NC

O

COOHNC HN

N

NH2

(4) 95

NC

NC HN

N

NH2

(1) 90

NC

NC HN

N

NH2

(20) 82

NC

NC NH

HO

N

NH2

(17) 73

NC

NC HN

N

NH2

NO2

(14) 90

NC

Cl

NC HN

N

NH2

(11) 91

(8) 79

NC

Cl

NC HN

N

NH2

NC

O

HOOC

NC HN

N

NH2

(5) 89

NC

O

ONC HN

N

NH2

(2) 91

NC

NC HN

N

NH2

(18) 88

NC

NC NH

N

NH2

(15) 78

NC

NC HN

N

NH2

(12) 92

(9) 84

NC

Cl

NC HN O

NH2

N

NC

O

HO

NC HN

N

NH2

(6) 87

NC

O

NC HN

N

NH2

(3) 93

NC

NC NH2

N

NH2

Scheme 4


Tabl

e2

Corrosio

nratesurface

covering

and

corrosioninhibitio

neffi

ciency

of1

56

and8inhibitors

atroom

temperature

No

Dose(ppm

)1day

3days

5days

7days

9days

K(m


θη(

)K(m


θη(

)K(m


(θ)

η(

)K(m


θη(

)K(m


θη(

)Blank

0001590

mdashmdash

0001404

mdashmdash

0001484

mdashmdash

000171

mdashmdash

0001968

mdashmdash

1200

0001267

0203

203

0001029

02665

2665

0001046

02949

2949

000116

03168

3168

0001202

03891

3891

400

0001059

03337

3337

0000876

03755

3755

0000886

04027

4027

0000911

04673

4673

0000922

05316

5316

800

000090

04321

4321

0000750

04657

4657

0000732

05068

5068

0000705

05874

5874

0000704

06421

6421

5200

0001057

03350

3350

0000832

04072

4072

0000842

04327

4327

0000873

04892

4892

0000850

05678

5678

400

0001010

03642

3642

0000794

04341

4341

0000795

04642

4642

0000839

05089

5089

0000806

05902

5902

800

0000832

04767

4767

0000617

05601

5601

0000607

05910

5910

0000582

06594

6594

0000569

07104

7104

6200

0001148

02779

2779

0000983

02997

2997

0001000

03261

3261

0001100

03564

3564

0001097

04423

4423

400

0001021

03576

3576

0000801

0429

429

0000793

04654

4654

0000895

04762

4762

0000911

05369

5369

800

0000939

04092

4092

0000781

04432

4432

0000752

04929

4929

0000735

05697

5697

0000748

06199

6199

8200

0001149

02772

2772

0000979

03021

3021

0001021

03120

3120

0001153

03254

3254

0001169

04060

4060

400

000104

03415

3415

0000800

04296

4296

0000776

04771

4771

0000846

05048

5048

0000871

05573

5573

800

0000940

04083

4083

0000767

04532

4532

0000686

05374

5374

0000653

06181

6181

0000654

06675

6674










202224262830323436384042444648505254565860

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)

Time (h)

15

68


Time (h)

15

68

303234363840424446485052545658606264

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

η (

)


Time (h)

15

68

38404244464850525456586062646668707274767880

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)























4 Conclusion


Data Availability




Acknowledgments


References








































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls






Wo (1)


Wo1113888 1113889 times 100 (2)

k W

St (3)



X


CHOCN CatalystEtOH

X

NC

NC

N

NH2

HN R1ndash20

Reflux

R=aryl alkyl

+ +

CN

H2N R

Scheme 1

X


CHOCN

X

NC

NC

N

NH2

1ndash20

Fusion

R=aryl alkyl

+ +CN

H2N R

HN R

Scheme 2

ndashX

X

1ndash20

XCHO

NC

NC

NH NH2

Aromatization

NC

NC

ndashH2

NH2NH2

X

X

NC NC

NC NC

NCNC

NCNC

C

C

C C C

CC H

X

C

C

N

N

NH

NH

NH

C N

H2N R

HN RHN R

HN R

+

HN R

Scheme 3









(19) 84

NC

NC NH

N

NH2

(16) 81

NC

NC HN

N

NH2

OCH3

(13) 88

NC

Cl

NC HN

N

NH2

NO2

(10) 76

(7) 82

NC

O

ONC HN

N

NH2

NC

O

COOHNC HN

N

NH2

(4) 95

NC

NC HN

N

NH2

(1) 90

NC

NC HN

N

NH2

(20) 82

NC

NC NH

HO

N

NH2

(17) 73

NC

NC HN

N

NH2

NO2

(14) 90

NC

Cl

NC HN

N

NH2

(11) 91

(8) 79

NC

Cl

NC HN

N

NH2

NC

O

HOOC

NC HN

N

NH2

(5) 89

NC

O

ONC HN

N

NH2

(2) 91

NC

NC HN

N

NH2

(18) 88

NC

NC NH

N

NH2

(15) 78

NC

NC HN

N

NH2

(12) 92

(9) 84

NC

Cl

NC HN O

NH2

N

NC

O

HO

NC HN

N

NH2

(6) 87

NC

O

NC HN

N

NH2

(3) 93

NC

NC NH2

N

NH2

Scheme 4


Tabl

e2

Corrosio

nratesurface

covering

and

corrosioninhibitio

neffi

ciency

of1

56

and8inhibitors

atroom

temperature

No

Dose(ppm

)1day

3days

5days

7days

9days

K(m


θη(

)K(m


θη(

)K(m


(θ)

η(

)K(m


θη(

)K(m


θη(

)Blank

0001590

mdashmdash

0001404

mdashmdash

0001484

mdashmdash

000171

mdashmdash

0001968

mdashmdash

1200

0001267

0203

203

0001029

02665

2665

0001046

02949

2949

000116

03168

3168

0001202

03891

3891

400

0001059

03337

3337

0000876

03755

3755

0000886

04027

4027

0000911

04673

4673

0000922

05316

5316

800

000090

04321

4321

0000750

04657

4657

0000732

05068

5068

0000705

05874

5874

0000704

06421

6421

5200

0001057

03350

3350

0000832

04072

4072

0000842

04327

4327

0000873

04892

4892

0000850

05678

5678

400

0001010

03642

3642

0000794

04341

4341

0000795

04642

4642

0000839

05089

5089

0000806

05902

5902

800

0000832

04767

4767

0000617

05601

5601

0000607

05910

5910

0000582

06594

6594

0000569

07104

7104

6200

0001148

02779

2779

0000983

02997

2997

0001000

03261

3261

0001100

03564

3564

0001097

04423

4423

400

0001021

03576

3576

0000801

0429

429

0000793

04654

4654

0000895

04762

4762

0000911

05369

5369

800

0000939

04092

4092

0000781

04432

4432

0000752

04929

4929

0000735

05697

5697

0000748

06199

6199

8200

0001149

02772

2772

0000979

03021

3021

0001021

03120

3120

0001153

03254

3254

0001169

04060

4060

400

000104

03415

3415

0000800

04296

4296

0000776

04771

4771

0000846

05048

5048

0000871

05573

5573

800

0000940

04083

4083

0000767

04532

4532

0000686

05374

5374

0000653

06181

6181

0000654

06675

6674










202224262830323436384042444648505254565860

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)

Time (h)

15

68


Time (h)

15

68

303234363840424446485052545658606264

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

η (

)


Time (h)

15

68

38404244464850525456586062646668707274767880

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)























4 Conclusion


Data Availability




Acknowledgments


References








































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls











(19) 84

NC

NC NH

N

NH2

(16) 81

NC

NC HN

N

NH2

OCH3

(13) 88

NC

Cl

NC HN

N

NH2

NO2

(10) 76

(7) 82

NC

O

ONC HN

N

NH2

NC

O

COOHNC HN

N

NH2

(4) 95

NC

NC HN

N

NH2

(1) 90

NC

NC HN

N

NH2

(20) 82

NC

NC NH

HO

N

NH2

(17) 73

NC

NC HN

N

NH2

NO2

(14) 90

NC

Cl

NC HN

N

NH2

(11) 91

(8) 79

NC

Cl

NC HN

N

NH2

NC

O

HOOC

NC HN

N

NH2

(5) 89

NC

O

ONC HN

N

NH2

(2) 91

NC

NC HN

N

NH2

(18) 88

NC

NC NH

N

NH2

(15) 78

NC

NC HN

N

NH2

(12) 92

(9) 84

NC

Cl

NC HN O

NH2

N

NC

O

HO

NC HN

N

NH2

(6) 87

NC

O

NC HN

N

NH2

(3) 93

NC

NC NH2

N

NH2

Scheme 4


Tabl

e2

Corrosio

nratesurface

covering

and

corrosioninhibitio

neffi

ciency

of1

56

and8inhibitors

atroom

temperature

No

Dose(ppm

)1day

3days

5days

7days

9days

K(m


θη(

)K(m


θη(

)K(m


(θ)

η(

)K(m


θη(

)K(m


θη(

)Blank

0001590

mdashmdash

0001404

mdashmdash

0001484

mdashmdash

000171

mdashmdash

0001968

mdashmdash

1200

0001267

0203

203

0001029

02665

2665

0001046

02949

2949

000116

03168

3168

0001202

03891

3891

400

0001059

03337

3337

0000876

03755

3755

0000886

04027

4027

0000911

04673

4673

0000922

05316

5316

800

000090

04321

4321

0000750

04657

4657

0000732

05068

5068

0000705

05874

5874

0000704

06421

6421

5200

0001057

03350

3350

0000832

04072

4072

0000842

04327

4327

0000873

04892

4892

0000850

05678

5678

400

0001010

03642

3642

0000794

04341

4341

0000795

04642

4642

0000839

05089

5089

0000806

05902

5902

800

0000832

04767

4767

0000617

05601

5601

0000607

05910

5910

0000582

06594

6594

0000569

07104

7104

6200

0001148

02779

2779

0000983

02997

2997

0001000

03261

3261

0001100

03564

3564

0001097

04423

4423

400

0001021

03576

3576

0000801

0429

429

0000793

04654

4654

0000895

04762

4762

0000911

05369

5369

800

0000939

04092

4092

0000781

04432

4432

0000752

04929

4929

0000735

05697

5697

0000748

06199

6199

8200

0001149

02772

2772

0000979

03021

3021

0001021

03120

3120

0001153

03254

3254

0001169

04060

4060

400

000104

03415

3415

0000800

04296

4296

0000776

04771

4771

0000846

05048

5048

0000871

05573

5573

800

0000940

04083

4083

0000767

04532

4532

0000686

05374

5374

0000653

06181

6181

0000654

06675

6674










202224262830323436384042444648505254565860

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)

Time (h)

15

68


Time (h)

15

68

303234363840424446485052545658606264

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

η (

)


Time (h)

15

68

38404244464850525456586062646668707274767880

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)























4 Conclusion


Data Availability




Acknowledgments


References








































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




Tabl

e2

Corrosio

nratesurface

covering

and

corrosioninhibitio

neffi

ciency

of1

56

and8inhibitors

atroom

temperature

No

Dose(ppm

)1day

3days

5days

7days

9days

K(m


θη(

)K(m


θη(

)K(m


(θ)

η(

)K(m


θη(

)K(m


θη(

)Blank

0001590

mdashmdash

0001404

mdashmdash

0001484

mdashmdash

000171

mdashmdash

0001968

mdashmdash

1200

0001267

0203

203

0001029

02665

2665

0001046

02949

2949

000116

03168

3168

0001202

03891

3891

400

0001059

03337

3337

0000876

03755

3755

0000886

04027

4027

0000911

04673

4673

0000922

05316

5316

800

000090

04321

4321

0000750

04657

4657

0000732

05068

5068

0000705

05874

5874

0000704

06421

6421

5200

0001057

03350

3350

0000832

04072

4072

0000842

04327

4327

0000873

04892

4892

0000850

05678

5678

400

0001010

03642

3642

0000794

04341

4341

0000795

04642

4642

0000839

05089

5089

0000806

05902

5902

800

0000832

04767

4767

0000617

05601

5601

0000607

05910

5910

0000582

06594

6594

0000569

07104

7104

6200

0001148

02779

2779

0000983

02997

2997

0001000

03261

3261

0001100

03564

3564

0001097

04423

4423

400

0001021

03576

3576

0000801

0429

429

0000793

04654

4654

0000895

04762

4762

0000911

05369

5369

800

0000939

04092

4092

0000781

04432

4432

0000752

04929

4929

0000735

05697

5697

0000748

06199

6199

8200

0001149

02772

2772

0000979

03021

3021

0001021

03120

3120

0001153

03254

3254

0001169

04060

4060

400

000104

03415

3415

0000800

04296

4296

0000776

04771

4771

0000846

05048

5048

0000871

05573

5573

800

0000940

04083

4083

0000767

04532

4532

0000686

05374

5374

0000653

06181

6181

0000654

06675

6674










202224262830323436384042444648505254565860

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)

Time (h)

15

68


Time (h)

15

68

303234363840424446485052545658606264

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

η (

)


Time (h)

15

68

38404244464850525456586062646668707274767880

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)























4 Conclusion


Data Availability




Acknowledgments


References








































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls












202224262830323436384042444648505254565860

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)

Time (h)

15

68


Time (h)

15

68

303234363840424446485052545658606264

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

η (

)


Time (h)

15

68

38404244464850525456586062646668707274767880

20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

η (

)























4 Conclusion


Data Availability




Acknowledgments


References








































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls
























4 Conclusion


Data Availability




Acknowledgments


References








































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls





































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




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