Ind. f n g . Chem. Prod.
96
Res. Dev. 1986, 25,96-102
cancies compared with the undoped Ti02. (3) A shift of the photoresponse toward longer wavelength (-500 nm) is observed compared with that for the undoped TiOz ceramic electrodes (-420 nm). Acknowledgment This work was supported by the Korea Traders Foundation. We thank Professor Robert G. Sauer for valuable comments on the manuscript. Registry No. Ti02,13463-67-7;Sbz03,1309-64-4;Ti, 7440-32-6. Literature Cited
Desplat, J. L. J . Appl. Phys. 1978, 4 7 , 5102. Fujishima. A.; Honda, K. Nature (London) 1972, 2 3 8 , 37. Hardee, K. L.; Bard, A. J. J. Electrochem. SOC. 1975, 122, 739. Matsumoto, Y . ; Kurimoto, J.; Amagasaki, Y.; Sato, E. J . Nectrochem. SOC. 1980, 127, 2148. Mollers, F.; Tolle, H. J.; Memming, R . J . Nectrochem. Soc. 1974, 121, 1160. Maxwell, L. H. Ceram. Bull. 1963, 4 2 , 438. Salvador, P. J . Appl. Phys. 1984, 55, 2977. Subbarao, S. N.; Yun, Y . H.; Kershaw, R.; Dwight, K.; Wold, A. Mater. Res. Bull. 1978, 13, 1461. Wilson, R . H. J . Appl. Phys. 1977, 4 8 , 4292. Yoon, K. H.; Yoon, S. 0. Jpn. J . Appl. Phys. 1984, 23, 1137. Yoon, K. H.; Kim, J. S.Jpn. J . Appl. Phys.. in press.
Received for review April 2 , 1985 Accepted August 30, 1985
Boddy, P. J. J . Nectrochem. Soc. 1988, 115, 199 Butler, M. A. J. Appl. Phys. 1977, 4 8 , 1914.
Syntheses of Derivatives of Alkylarylamines and Their Properties as Pickling Inhibitors of Carbon Steels and Stainless Steels Marek Studnlckl Institute of Inorganic Chemistry, 44- 101 Gliwice, Sowifisskiego 11, Poland
Preparation and application of pickling inhibitors derivatives of alkylarylamines in hydrochloric acid and sulfuric acid are described.
Introduction Application of corrosion inhibitors of metals in strongly corrosive media is the cheapest and best way to prevent corrosion. In recent years derivatives of alkylarylamines were found to be among the most effective inhibitors, and because of their good properties, they can compete with cheaper but less active inhibitors. The aims of this study were syntheses of (chloroalky1)arylamines and investigations of their properties (Studnicki, 1983, 1984, 1985). A new method of synthesizing monosubstituted derivatives of hydrazine that involves reaction of (chloroalky1)arylamines with hydrazinium carbonate was elaborated. This new approach gives higher yields of mono derivatives than by presently known methods (Ioffe et al., 1979; Osei-Twum et al., 1984; Pilgram and Skiles, 1983). These compounds were not isolated in these investigations as corrosion inhibitors. Their purification and analyses will be described in future publications. Hydrazine is readily alkylated by heating with haloalkanes, but it must be realized that alkylation can proceed further to form quaternary salts. Thus, from HzNNHzand RX one obtains not only RHNNH2but also RzNNH2and R3NNH2X-. One cannot obtain 1,2-dialkylhydrazines in this way. In order to convert hydrazine into a monoalkylhydrazine it is necessary to use a large excess of hydrazine to prevent further alkylation. If the R in RX is primary alkyl, it requires greater dilution than if R is secondary, as from 1O:l for ethylhydrazine to 4:l for isopropylhydrazine. To synthesize higher monoalkylhydrazines one must use alcohol as solvent; without it, only 1,l-dialkylhydrazines are obtained (Ioffe et al., 1979). A new synthesis of salts of S-(aminomethyl)- or S-(diaminomethy1)isothioureas was devised by reaction of N-chloromethyl o r N-dichloromethyl compounds with thiourea in the presence of stannous chloride. Known 0196-432118611225-0096$01.50/0
Scheme I' Ar-NH,
+ C1-R-CI
ArNH(R-C1)
+ H-B
A
-
SnC1,
t H' --+ (Cl-R)+NH,Ar
+
HCl
ArNHR-B.HC1
H-B = H-NH,, H-NH-DBA, H-NHNH,, H-SC(NH)NH, B
c
N
S
RCI, = methylene chloride, chloroform; Ar = 0-,m - , p-phenylene; 2, 3,4-dichlorophenyl; 3, -phenylf 4, 3chlorophenyl; 5 , 3-hydroxy phenyl; 6, 3-methoxyphenyl. A, Table I ; B, Table 11; C, Table 111; N, Table IV; S, Table V.
methods of preparation of these compounds rely on reaction in solvents (Autorenkollektiv, 1971; Freidlina et al., 1983; Pandeya and Ram, 1981). In thiourea the sulfur atom has strong electrophilic properties, and the basic nitrogen atoms increase the electron density on the sulfur, which means that the aliphatic halogens and thiourea easily form a salt: (a1iph)-C1 + SC(NHJ2
SnC1,
(a1iph)-S-C(NH)-NH, + HC1 (as salt)
Based on published information, the most commonly used corrosion inhibitors are meta-substituted anilines and derivatives and benzimidazole (Desai and Shah, 1972; Singh et al., 1972; Desai and Thanki, 1972; Desai, Gandhi, and Joshii, 1974; Patel and Franco, 1975;Talati and Patel, 1978; Aal and Abdel Assaf, 1980; Desai and Desai, 1981; Trabanelli et al., 1973; Berthold et al., 1978; Lomakin, 1979; 1980; Anderson, 1980; McCrory-Joy and Rosamila, 1982). Acidic pickling to clean the surfaces of apparatuses and devices is connected with corrosion of metals, and one must 8 1986 American
Chemical Society
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Table I. (Chloromethy1ene)anilines(A) Used as Corrosion Inhibitors of Stainless Steel 1H18N9T in 36% HC1 at 20 OC" 'H NMR Figure 1 CD30D no. structure Ar symbol 8CH 8*CH2 1A 2,3-dihydrobenz- DBA v 7.09 imidazol-2-yl chloride (DBA)Cl 2A ArNHCHzCl 3,4-dichlorophenyl 0 3.41 3A phenyl A 3.38 4A 3-chlorophenyl V 3.38 5A 3-hydroxyphenyl 0 3.75 6A 3-methoxyphenyl A 3.23 7B (DBA)NHz DBA 0 8A oxine Concentration of inhibitors,
lo-,
mol/dm3.
Table 11. Aminoalkyl Derivatives of 0 - , m-, p -Phenylenediamines (B) Used as Corrosion Inhibitors mol/dms) of Stainless Steel lH18N9T in 40% HCl mol/dms of Stannous Chloride without or with Figure 2 Ar symbol no. structure 1B [-ArNHCH(NH,)NH-1, p-phenylene 2B [-ArNHCH(NH2)NH-]..xSnC1, p-phenylene 3B [-ArNHCH(NH,)NH-], m-phenylene 4B [-ArNHCH(NH2)NH-In.xSnCl2 m-phenylene 9C (DBA)ZNH DBA (Table I) 11C (DBA)2NHd3nC12 DBA 8A oxine 8B SnCl,
use corrosion inhibitors. Savings result from the use of less acids and lime for neutralization. In addition, surface properties are improved by the lessened amount of evolved hydrogen. Corrosion inhibitors in acidic solutions are polyamines (Ruskol et al., 1984), triamines (Robinson, 1983),thiourea (Altsybeevaet al., 1968),and oxine (Gupta et al., 1981). Elsewhere (Studnicki, 1984)the good properties of 2-amino-2,3-dihydrobenzimidazole are noted. The experimental data describe inhibiting properties of derivatives of substituted amines (Scheme I): N-(chloromethy1)anilines (A); several amines of the structure (ArNH)&H-NH2 (B); 2-(arylamino)-2,3-dihydrobenzimidazole (C); several hydrazine derivatives of structures Ar-NH-CH,-NHNH, or (ArNH)&H-NHNH, (N); and several isothiourea derivatives (S) of structures ArNH-CH2-S-C(NH)NH2 or (ARNH),CH-S-C(NH)NH, as corrosion inhibitors of stainless steel and carbon steel in hydrochloric and sulfuric acids. The investigations were carried out by the known gravimetric method (Gupta et al., 1981)at 20 and 50 "C. The volume of evolved hydrogen at 50 "C was measured in time by a eudiometer. In Tables I-V are presented the investigated inhibitors. Concentration of inhibitors varied from 0.01 g/dm3 to 1.7 g/dm3.
Experimental Syntheses Hydrazinium Carbonate. Fifty percent aqueous hydrazine (500 cm3) was mixed with 500 cm3 of methanol. Carbon dioxide was passed through the mixture for 30 min; 218 g of COz was absorbed in the mixture. Poly[anilino( hydrazinomethy1ene)-p -imino]hydrazine (1N). Ten grams of poly[anilino(chloromethylene)-p-imino](Studnicki, 1983)was heated with 100 cm3of hydrazinium carbonate a t 100 "C. After filtration and evaporation, 19 g of product (1N)was obtained. Poly[ anilino( hydrazinomethy1ene)-m-imino]hydrazine (2N). Ten grams of poly[anilino(chloromethylene)-m-imino]was heated a t 100 "C with 100 cm3
Table 111. Derivatives of 1-(2,3-Dihydrobenzimidazo1-2-yl)-3-phenylmet hylenediimines (C) Used as Corrosion Inhibitors (0.171 g/dms) of Carbon Steel St-3S in 1 mol/dms HCl" or in 1 mol/dm3 H2S0,*at 20 OC
no. structure 7B DBA-NHZ 9C (DBA)zNH 5c 6C 7c 8C 2 s [-ArNHCH(SC(NH)NHz)NH-]".xSnCl,. xSC(NHzh 1OC [-ArNH(CH2COOH)CH(SC(NH)NHJNHCl(CHJJ'(0)(OH),-ln(CM* xSnC12xSC(NHz)z
Ar DBA (Table I) DBA phenyl 3-chlorophenyl 3-hydroxyphenyl 3-methoxyphenyl m-phenylene
m-phenylene
no.)
6CH
6'CH2
0 (3, 14) 6.65 A (3, 14) 6.73 1.94 v (3, 14) 2.07
(3, 14) 0 (4, 15) A (4, 15) (4, 15)
2.08 1.74 3.78
V (4, 15)
"Figures 3 and 4. *Figures 14 and 15.
Table IV. Mono Derivatives of Hydrazine Used as Corrosion Inhibitors (1.71 g/dms) of Carbon Steel St-3S in 10% HCl at 20 "C symbol (figure Ar no.) no. structure 1N [-ArNHCH(NHNH,)p-phenylene 0 (12) NH-In4.5NH2NHz*10HC1 2N [-ANHCH(NHNH2)m-phenylene A (12) . . NH-],GNH2NH,:l3HCl 3N (DBA)NHNH2*2NHZNHz* DBA (12) 5HC1 4N ArNHCH2NHNH2.2HCl 3-methoxyphenyl X (12) 5N NH2CSNH2.0.5SnClZ 0 (13) 8A oxine 0 (14) Table V. Derivatives of Thiourea Used as Corrosion Inhibitors (1.71 g/dms) of Carbon Steel St-3S in 18% HzS04 at 20 "C symbol (figure Ar no.) no. structure 1s [-ArNHCH(SC(NH)NH,)p-phenylene 0 (16) NH-] .xSNC12* 0.2NHzCSNHz 2 s [-ArNHCH(SC(NH)NH,)m-phenylene A (16) NH-],xSnCl,. 0.2NHZCSNHz 3 5 (DBA)SC(NH)NH2xSnClZ. DBA (Table I) 0 (16) 0.2NHZCSNH2 45 ArNHCh2SC(NH)NH,. 3-methoxyphenyl X (16) 1.5SnCl2-0.5NH,CSNH2 55 NH2CSNHz 0 (17)
of solution methanol-water of hydrazinium carbonate. After filtration and evaporation, 11.5 g of product (2N) was obtained. (2,3-Dihydrobenzimidazol-%-yl) hydrazine (3N).Ten grams of 2-chloro-2,3-dihydrobenzimidazole(Studnicki, 1983) was heated a t 100 "C with 100 cm3 of methanolwater solution of hydrazinium carbonate. After filtration and evaporation, 11.5 g of product (3N)was obtained. (m-Anisidinomethyl)hydrazine (4N).Four grams of N-(chloromethy1)-m-anisidine(Studnicki, 1983)was heated a t 100 "C with 100 cm3 of methanol-water solution of hydrazinium carbonate. After filtration and evaporation,
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Ind. Eng. Chem. Prod. Res. Dev., Vol. 25, No. 1, 1986
3.5 g of product (4N) was obtained. Poly[anilino(S-isothioureidomethy1ene)-g-imino] (1s). Ten grams of poly[anilino(chloromethylene)-p-imin01 was ground and mixed in a porcelain mortar with 3 g of thiourea. The mixture was heated a t 60 "C for 20 h, and 12.9 g of product (1s) was obtained. Poly[ anilino ( Sh o thioureidometh ylene) -m-imino] (2s). Thirty-one grams of poly[anilino(chloromethylene)-m-imino] was mixed and ground in a porcelain mortar with 15.2 g of thiourea. The mixture was heated at 150 "C for 4 h; 44.2 g of product (25) was crystallized from methanol. S - ( m-anisidinomethyl)isothiourea(45). Four grams of N-(chloromethy1)-m-anisidinewas mixed and ground with 7.7 g of stannous chloride and 3 g of thiourea. The mixture was heated a t 60 O C for 19 h; 13.5 g of product (4s)was obtained. All these compounds are new, but for corrosion investigations it was not necessary to isolate these pure compounds. Purifications and analyses of these compounds will be described in future publications. Corrosion Investigations Degree of protection " 2of inhibitors was measured by gravimetric method (Gupta et al., 1981) log T b l
z= ( y ) 1 0 0 . where io is the corrosion rate without inhibitor and i is the corrosion rate with inhibitor. For group S 2" =
(y)'oo'
Figure 1. Degree of protection of derivatives of (chloromethylenelanilines (A) and 7B as corrosion inhibitors in time (h). Pickling parameters and inhibitors, Table I. Z, %
where i" is the corrosion rate with 1.71 g/dm3 of thiourea and Z" is only for group S investigated in 18% sulfuric acid a t 20 "C (steel St-3s). The volume of evolved hydrogen V,, was measured in time by a eudiometer.
Results and Discussion Corrosion Inhibitors in Hydrochloric Acid. The first investigations were carried out in 36% hydrochloric acid for stainless steel 1H18N9T for group A and 7B inhibitors. However, from the beginning of pickling 3A inhibitor was slightly better than 6A, but in time the degree of protection decreases more than does the degree of protection of 6A. It was confirmed that the best inhibitors were 7B and 6A. All investigated inhibitors of group A have a better degree of protection than oxine 8A (Figure 1). Further investigations were carried out in 40% HCI for stainless steel 1H18N9T for aminoalkyl derivatives of 0-, m-, and p-phenylenediamines B and ( 9 0 . It was corroborated that these inhibitors have better properties in the presence of stannous chloride. It was found that a derivative of m-phenylenediamine 4B has better properties than the other inhibitors in the presence of stannous chloride. Without the addition of SnCI2after longer time of pickling, the best properties were demonstrated by 1B derivatives of p-phenylenediamine (Figure 2). Compounds of group C were investigated in 1N HC1 for carbon steel St-3s. Except for 7C all the investigated inhibitors have better degrees of protection 2, than the earlier investigated compounds 7B and 9C. The best properties were shown for the derivative of m-anisidine (8C) (Figures 3 and 4). Degree of protection 2, of 8C decreased only slightly if the concentration of inhibitor decreased from 0.17 mol/
Figure 2. Degree of protection of aminoalkyl derivatives of a-, m-, p-phenylenediamines (B) and 9C and 11C as corrosion inhibitors in time (h). Pickling parameters and inhibitors, Table 11.
dm3to 0.01 mol/dm3 (Figure 5 ) and was better than oxine (8A). The best acidity properties for inhibitor 8C in hydrochloric acid were found for 2.5 N HCl (Figure 6). Influence of the structure of the aromatic amine fragment in the inhibitor is presented in (Figure 7). For groups of compounds A and C it was confirmed that the degree of protection of inhibitors increases in the range ( 5 ) m-OH < (4) m-C1 < (2) 3,4-diC1 < (3) ani1 < (6) manisidine. In spite of certain successes, it seems that influence of substituents on chemical shifts 'H NMR of protons and their reactivity is not the same. The correlations described in the literature between influence of substituents in meta position on chemical shifts of protons were bad (Shorter, 1980). The substituent's own magnetic field can change in certain distance the field influences on protons. The magnetic effect is connected with anisotropy of bonds, but its strength is dependent on distance and angle. If the molecule has a dipole that is caused by OH, OCH,, C1, et,c., it produces an electric field that causes shifts of
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Ind. Eng. Chem. Prod. Res. Dev., Vol. 25, No. 1, 1986
99
ZC
1
80
QP QblS 125
L5
5 nd/dma
Figure 6. Influence of concentration of hydrochloric acid on degree of protection of inhibitor 8C. Pickling time 24 h; pickling parameters and concentration of inhibitor, Table 111.
Figure 3. Degree of protection of derivatives of 1-(2,3-dihydrobenzimidazol-2-yl)-3-phenylmethylenediimine (C) and compounds 7B and 9C as corrosion inhibitors in time (days). Pickling parameters in hydrochloric acid and inhibitors, Table 111. 40
Z$f. 0
"
7c
68 C
5
"
80
?5
TO
85
90
4%
Figure 7. Degree of protection of inhibitors A and C groups with the same aromatic substituents. Pickling time in the presence of inhibitors A 34 days, in the presence of inhibitors C 10 days. Pickling parameters of inhibitors A, Table I; pickling parameters of inhibitors C, Table 111. Aromatic substituents as Scheme I: 2, 3,4dichlorophenyl; 3, phenyl; 4,3-chlorophenyl; 5,3-hydroxyphenyl; 6, 3-methoxyphenyl.
701
i
2
6
3
40 days
Figure 4. Degree of protection of derivatives of 1-(2,3-dihydrobenzimidazol-2-yl)-3-phenylmethylenediimine (C) and compound 25 in time (days). Pickling parameters in hydrochloric acid and inhibitors, Table 111. 2%
-
0
$5LY-NU-'"2-NH@JOCH3
"1 44
L 00407 . b,2tU
o,is
05
dH
QSI
&
Q%
0,SS
dS6
Pi7
4'69
Figure 5. Degree of protection of inhibitor 8C compared to oxine in regard to concentration of inhibitors. Pickling time in hydrochloric acid 24 h; pickling parameters, Table 111.
Figure 8. Correlation between degree of protection of inhibitors A 2, (Scheme I) and chemical shift 'H NMR of protons CH2 in CD,OD of these inhibitors. Points as Figure 7 and Scheme I: log 2, = -40.2 + 21.8, r = 0.8858. log
electrons along the axis of the C-H bond and changes the chemical shifts of protons. In many cases it is possible to separate this effect from induction if the dipole is sufficiently distant from the observed proton (Zschunke,1976).
Substituents in the benzene ring influence the x electrons and cause "uncover effect" (Shorter, 1980). Linear correlation between log 2, and log 8ACH,and log 2 ~ / 1 0 0and log 8CCHZ(Figures 8 and 9) points at resem-
OdrzS' 0.05
O,Ga5?
PI
Otri9,k"
100
Ind. Eng. Chem. P r d . Res. Dev., Vol. 25, No. 1, 1986 le K QD3
'
I\
Figure 11. Correlation between log K50'c and degree of protection Zc/lOOof inhibitors C. Points as Figure 7 and Scheme I: log K"" = -47.4 log Zc/lOO + 1.6, r = 0.9051. ZN %
i
'
A
2
5
4N
x 4N
2N
o BA
6
8
&us
n 3N
Figure 12. Degree of protection of inhibitors N in time (days). Pickling parameters, Table IV. 401
'
-
