Synthesis and properties of multifunctional hindered amine light stabilizers

Article abstract of DOI:10.1515/hc-2013-0153

A series of multifunctional hindered amine light stabilizers (HALSs) for monomers were designed and synthesized from cyanuric chloride, allylamine, 2,2,6,6-tetramethylpiperidine-4-ol or 1,2,2,6,6-pentamethylpiperidine-4-ol, and 2-(2-hydroxyphenyl)-1,2,3-b

Full text of DOI:10.1515/hc-2013-0153

ꢁꢁꢁꢂ
ꢀHeterocycl. Commun. 2014; 20(1): 15–20
DOI 10.1515/hc-2013-0153ꢀ
Xiaofeng Gou*, Dong Liu, Chengwen Hua, Junlong Zhao and Wen Zhang
Synthesis and properties of multifunctional
hindered amine light stabilizers
Abstract: A series of multifunctional hindered amine of autoxidation by transformation of the parent amines
light stabilizers (HALSs) for monomers were designed to nitroxide radicals either by reaction with peroxy radi-
and synthesized from cyanuric chloride, allylamine, cals or occasionally by reaction with singlet oxygen. The
2,2,6,6-tetramethylpiperidine-4-ol or 1,2,2,6,6-pentameth- nitroxide radicals stop oxidative degradation by coupling
ylpiperidine-4-ol, and 2-(2-hydroxyphenyl)-1,2,3-benzo- of alkyl radicals [9, 10]. In contrast to 2,2,6,6-tetramethylpi-
triazole derivatives through nucleophilic substitution. peridines, 2-(2-hydroxyphenyl)-1,2,3-benzotriazole deriva-
1
13
The new stabilizers were confirmed by H NMR, C NMR, tives belong to UVAs [11]. They are transparent to visible
FT-IR, ESI-HRMS and elemental analysis. The synthesized light and are assumed to dissipate the absorbed energy
compounds 5a–f were evaluated for their antioxidant and in a harmless manner, that is, by converting the absorbed
anti-aging properties. The results indicate that the new photon energy into heat without being chemically affected.
HALSs can considerably improve polymer photostability.
If basic HALSs, benzotriazole and polymerizable allyl
group fragments are linked through s-triazine ring in one
Keywords: HALSs; 2-(2-hydroxyphenyl)-1,2,3-benzotria- molecule, this could result in a new stabilizer type with
zole; photostability; s-triazine; 2,2,6,6-tetramethylpiperi- combined stabilizing effect. These moieties may display
dine; UV absorber.
a synergistic effect in one molecule [12–15]. Bojinov and
co-workers have synthesized several bifunctional HALSs
linked to polymerizable monomers [16–19].
This paper describes the synthesis of compounds
5a–f composed of multifunctional HALSs, a benzotriazole
group, a polymerizable allyl group and a flame-retardant
triazine moiety. UV-Vis absorption and thermal stability of
these stabilizers were studied. Their influence on the pho-
tostability of copolymers has been investigated.
*Corresponding author: Xiaofeng Gou, College of Chemistry and
Materials Science, Northwest University, Xi’an 710069, P.R. China,
e-mail: gou.xiaofeng@163.com
Dong Liu, Chengwen Hua, Junlong Zhao and Wen Zhang: College
of Chemistry and Materials Science, Northwest University, Xi’an
710069, P.R. China
Introduction
The polymeric materials exposed to sunlight undergo Results and discussion
degradation which decreases the use value and shortens
their service life, mainly by photooxidation. The inherent The synthetic routes are shown in Schemes 1–3. All
characteristic and appearance of polymer materials may reactions were monitored by TLC on silica gel and the
be weakened as a result of photodegradation [1–3]. Hence, synthesized products 2a,b, 3a,b, 4a–c and 5a–f were
polymeric auxiliaries are being studied and analyzed.
characterized by melting points, elemental analyses,
1
Hindered amine light stabilizers (HALSs) are one of FT-IR, ESI-HRMS and H NMR spectra. All analytical data
the most important thermal/light stabilizing agents of are in agreement with the desired structures.
polymeric materials. They are widely available with low
Photostabilization efficiency, oxidation resistance and
toxicity and low cost, and they have excellent compat- miscibility with polymeric materials (PE and PP) of com-
ibilities with a broad range of commercially significant pounds 5a–f were studied. The results indicate that the
polymeric materials. HALSs have a good photostabiliz- solubility of new compounds 5a–f is better than that for the
ing effect on organic materials, which may be 2–4 times previously reported compounds by Bojinov and co-workers
higher than that of ultraviolet stabilizers [4, 5]. In general, [16–19]. The miscibility was evaluated by using the smooth
HALSs are applied with other antioxidants and ultravio- degree (S). The miscibility of the new stabilizers is 0.63,
let absorbers (UVAs). However, these two groups differ whereas it is 0.51 for the previously reported compounds.
in their action, although both are classified as photodeg- The analysis of the results shows that the compounds have
radation stabilizers [6–8]. HALSs inhibit the processes considerably high photostabilizing efficiency.
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 5/26/15 11:04 AM

ꢁꢁꢁꢂ
16ꢀ
ꢀX. Gou et al.: Multifunctional hindered amine light stabilizers
R1
N
R1
N
R1
N
Me
Me
Me
Me
Cl
Me
Me
Me
Me
Me
Me
Me
Me
toluene
catalyst
H2N
N
N
K2CO3, N2
Cl
N
Cl
OH
O
N
Cl
O
N
HN
N
N
N
N
1a,b
2a,b
3a,b
Cl
Cl
1
a
: R = H
b: R1 = Me
Scheme 1ꢀ
H2N
NH2
R2
NH2
OH
R2
N
NCl
R2
N
N
H2N
NH2
NaNO2, HCl
< 5°C
OH
OH
R2
NH2
4a: R2 = H
N
CuSO4 5H2O
MeOCH2CH2OH
N
2
4b:
4c:
R = Me
R = Cl
N
2
OH
4a-c
Scheme 2ꢀ
As shown in Figure 1, the absorption bands of com- property of the copolymer poly(MMA-co-HS-508) and
pounds 5a–f are observed at 300–350 nm. Their absorp- homo-PMMA, according to the method for thermal sta-
tion intensity is higher than that of the HALS HS-508. And bility of polyethylene pipe and tube fittings (GB = T17391-
the maximum molar extinction coefficients of the title com- 1998, China). The results are summarized in Figure 3. The
pounds are 9.28 × 104 L/mol·cm-1 (5a), 3.63 × 104 L/mol·cm-1 mass decomposition rate of the copolymers poly(MMA-co-
(5b), 1.00 × 105 L/mol·cm-1 (5c), 5.78 × 104 L/mol·cm-1 (5d), stabilizers 5a–f) is lower than the homo-PMMA. The data
4.06 × 104 L/mol·cm-1 (5e) and 3.29 × 104 L/mol·cm-1 (5f), demonstrate that the new HALSs show a good stabilizing
but for HS-508, the coefficient is 3.15 × 104 L/mol·cm-1. The effect. All stabilizers 5a–f considerably improve polymer
results of TGA tests are shown in Figure 2 with a signifi- photostability.
cant mass loss observed between 203°C and 254°C.
To investigate the influence of the monomers 5a–f
on the photostability of the copolymers, the copolymers Conclusion
were tested by the simulated aging experiment [20–22].
The antioxidation property of the copolymers poly(MMA- In this work, the multifunctional HALSs 5a–f were synthe-
co-stabilizers 5a–f) were tested and compared with the sized in good yields by using an efficient and convenient
R1
N
Me
Me
Me
Me
O
N
HN
AcOH, AcONa
3a-b 4a-c
∆
N
N
R2
HN
N
N
N
5a-f
HO
5a: R1 = R2 = H
5d: R1 = R2 = Me
1
2
1
2
5b
5e
: R = Me; R = H
: R = H; R = Cl
1
2
1
2
5c:
5f:
R = H; R = Me
R = Me; R = Cl
Scheme 3ꢀ
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 5/26/15 11:04 AM

ꢂꢁꢁꢁ
X. Gou et al.: Multifunctional hindered amine light stabilizersꢀ
ꢀ17
2.5
2.0
1.5
1.0
0.5
0.0
method. Their UV-vis absorption, thermal stability and
photostability were studied. The results indicate that the
oxidation resistance and photostabilization efficiency of
the new stabilizers are better in comparison to the mar-
keted stabilizer HS-508 in MMA.
5c
5a
5d
5e
5b
5f
Experimental
Cyanuric chloride, m-phenylenediamine, o-aminophenol, 2-amino-
4-methylphenol, 2-amino-4-chlorophenol, allylamine, 2,2,6,6-tetra-
methylpiperidin-4-ol (1a) and methyl trioctyl ammonium chloride
(Aliquat 336) were purchased from Sinopharm Chemical Reagent
Co., Ltd. 1,2,2,6,6-Pentamethylpiperidine-4-ol (1b) was synthesized
and purified as previously described [23, 24]. The 2-hydroxyphenyl-
benzotriazole derivatives 4a–c [25] were synthesized as previously
described.
HS-508
250
300
350
400
450
Wavelength (nm)
Figure 1ꢀUV-Vis spectra of compounds 5a–f and the reference stabi-
lizer HS-508 in methanol (c = 2.000 ×10 mol/L) at room temperature.
-4
1H NMR (400 MHz) and 13C NMR (100 MHz) spectra were
recorded on a Varian INOVA spectrometer in CDCl3 and acetone-d6.
UV-Vis spectra were recorded on a Shimadzu UV-1700 ultraviolet-
visible spectrophotometer with 2 nm resolution, at room tempera-
ture in methanol. TG curves were recorded on an Netzsch STA 449C
TGA instrument from ambient temperature to 500°C at a heating
rate of 20°C/min in dry nitrogen. IR spectra were taken on a Perkin-
Elmer 1600 FT-IR spectrometer in KBr pellets. Aging performance
was tested on a ZN-P fluorescence-UV light aging box. Mass spec-
trometry was carried out with an Agilent AXIMA-CFR-plus MALDI-
TOF mass spectrometer. The reaction course and purity of the final
products were followed by TLC on silica gel (Sinopharm Chemical
Reagent Co., Ltd., F60254 20 × 20, 0.2 mm). Elemental analysis was
carried out with a Perkin-Elmer 240C instrument. Melting points
were determined using a XT-4 melting point microscope without
correction.
100
5a
5b
5c
5d
5e
90
80
70
60
50
40
30
20
5f
HS-508
100
150
200
250
300
350
400
450
500
Temperature (°C)
Figure 2ꢀResults of the TGA test done over a temperature range from
ambient to 500°C with a heating rate of 20°C/min in dry nitrogen.
General procedure for synthesis of
compounds 3a–b
30
A mixture of 2,2,6,6-tetramethylpiperidin-4-ol 1a, b (0.01 mol), finely
ground sodium hydroxide (2.5 equiv.) and Aliquat 366 (0.04 g, 0.1
mmol) in toluene (30 mL) was stirred for 10 min. Then a solution of
cyanuric chloride (1.84 g, 0.01 mol) in 20 mL of toluene was added
at 0°C dropwise with vigorous stirring over a period of 30 min. The
reaction process was monitored by TLC with methanol/ethyl acetate
(1:5, V/V) as the eluent. Afer 4 h of stirring under the same condi-
tions, the mixture was diluted in 25 mL of water before separation of
the organic layer. The organic solution was washed with saturated
solution of sodium chloride ( × 3), dried over anhydrous sodium sul-
fate. This solution contained 2-(2,2,6,6-tetramethylpiperidin-4-oxy)-
4,6-dichloro-s-triazine 2a,b. Mp was 123.9–125.4°C for compound 2a
(lit. mp 125–126°C [26, 27]).
poly (MMA-co-5a)
poly (MMA-co-5b)
poly (MMA-co-5c)
poly (MMA-co-5d)
poly (MMA-co-5e)
poly (MMA-co-5f)
poly (MMA-co-HS508)
homo-polyMMA
25
20
15
10
5
0
A solution of allylamine (0.57 g, 0.01 mol) in toluene (20 mL) was
added dropwise under vigorous stirring at 40°C to a mixture of the
intermediate 2a,b (1 equiv.) in toluene (20 mL) and anhydrous potas-
0
50
100
Time (h)
150
200
Figure 3ꢀThe antioxidation properties of the copolymers poly(MMA- sium carbonate (1 equiv.) over a period of 30 min under dry nitro-
co-stabilizers 5a–f) as tested in the fluorescence-UV light aging box. gen. Afer 3 h of stirring at 40°C, the reaction mixture was cooled to
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 5/26/15 11:04 AM

ꢁꢁꢁꢂ
ꢀX. Gou et al.: Multifunctional hindered amine light stabilizers
18ꢀ
room temperature. The organic phase was filtered and concentrated 2-(5-Amino-2H-benzotriazol-2-yl)-4-methylphenol
(4b)ꢀYield
in vacuo to yield a pale yellow residue. Chromatography on silica gel 86%; mp 208.3–209.1°C; 1H NMR (CDCl3): δ 2.39 (s, 3H, CH3), 4.02 (br s,
methanol/ethyl acetate (1:7) gave 3a,b as a white solid.
2H, NH2), 6.93–8.11 (m, 6H, ArH), 11.18 (br s, H, OH); ESI-HRMS, m/z,
(M+H+): Calcd 241.1093, observed 241.1089. Anal. Calcd for C13H12N4O:
C, 64.99; H, 5.03; N, 23.32. Found: C, 65.08; H, 5.12; N, 23.39.
2-Allylamino-4-(2,2,6,6-tetramethylpiperidin-4-yloxy)-6-chlo-
ro-s-triazine (3a)ꢀYield 62%; mp 157.2–160.0°C; 1H NMR (CDCl3):
δ 1.21 (s, 6H, piperidine 2 × CH3), 1.29 (s, 6H, piperidine 2 × CH3),
1.55 (br s, 1H, piperidine NH), 2.09 (d, J = 12.0 Hz, 4H, piperidine 2 ×
CH2), 4.08 (d, J = 5.2 Hz, 2H, allyl CH2), 5.12–5.27 (m, H, piperidine CH),
5.42 (d, J = 10.0 Hz, 2H, CH2 = ), 5.87–5.92 (m, H, -CH =), 6.27 (br s, 1H,
allyl NH); ESI-HRMS, m/z, (M+H+): Calcd 326.1737, observed 326.1748.
Anal. Calcd for C15H24N5OCl: C, 55.29; H, 7.42; N, 21.49. Found: C, 55.34;
H, 7.38; N, 21.41.
2-(5-Amino-2H-benzotriazol-2-yl)-4-methylphenol
(4c)ꢀYield
76%; mp 222.4–223.8°C; 1H NMR (CDCl3): δ 4.05 (s, 2H, NH2),
6.90–8.31 (m, 6H, ArH), 11.37 (s, H, OH); ESI-HRMS, m/z, (M+H+):
Calcd 241.1093, observed 241.1089. Anal. Calcd for C12H9N4OCl: C,
55.29; H, 3.48; N, 21.49. Found: C, 55.36; H, 3.52; N, 21.61.
2-Allylamino-4-(1,2,2,6,6-pentamethylpiperidine-4-yloxy)-
6-chloro-s-triazine (3b)ꢀYield 60%; mp 136.4–138.1°C; 1H NMR
(CDCl3): δ 1.11 (s, 6H, piperidine 2 × CH3), 1.19 (s, 6H, piperidine
2 × CH3), 2.15 (d, J = 11 Hz, 4H, piperidine 2 × CH2), 2.27 (s, 3H, CH3-N),
4.09 (d, J = 5 Hz, 2H, allyl CH2), 5.17–5.27 (m, H, piperidine CH), 5.28
(d, J = 7.0 Hz, 2H, CH2 = ), 5.80–5.91 (m, H, -CH =), 6.24 (br s, 1H, allyl
NH); ESI-HRMS, m/z, (M+H+): Calcd 340.1901, observed 340.1904.
Anal. Calcd for C16H26N5OCl: C, 56.54; H, 7.71; N, 20.61. Found: C, 56.50;
H, 7.67; N, 20.53.
General procedure for synthesis of
compounds 5a–f
To a solution of 5-aminobenzotriazole derivative 4a–c (0.01 mol) in
30 mL of glacial acetic acid were added 0.082 g (0.01 mol) of sodium
acetate and 0.01 mol of allylaminotriazinylpiperidine 3a,b. The
resulting mixture was stirred for 2 h at 120°C and then afer cool-
ing poured into 50 mL of water. The crude precipitated product was
isolated by filtration and purified using column chromatography on
silica gel eluting with methanol/ethyl acetate/triethylamine (2:16:1)
to give 5a–f as a pale yellow solid.
General procedure for synthesis of
compounds 4a–c
2-[2-(2-Hydroxyphenyl)benzotriazol-5-amino]-4-allylamino-
6-(2,2,6,6-tetramethylpiperidin-4-yloxy)-s-triazine (5a)ꢀYield
1
69%; mp 225.1–227.6°C; H NMR (acetone-d6): δ 1.26 (s, 12H, piperi-
A solution of 0.01 mol o-aminophenol (2-amino-4-methylphenol or
2-amino-4-chlorophenol) in 15 mL of water and 2 mL of concentrated
hydrochloric acid was diazotized at 0–5°C in the presence of 0.04 g
of copper(II) sulfate pentahydrate with a solution of sodium nitrite
(1 equiv.) in 5 mL of water. The cold solution (5°C) of the diazonium
chloride was added dropwise to a solution (5°C) of m-phenylenedi-
amine (1.08 g, 0.01 mol) in 20 mL of water and 1 mL of concentrated
hydrochloric acid over a period of 20 min. To this mixture, a solution
of sodium acetate (10 mL, 40%) was added over a period of 0.5 h with
stirring at 5°C. Afer 2 h of stirring at room temperature, the reaction
mixture was treated with 5 mL of 25% aqueous ammonium hydroxide
solution (to pH = 8) and the precipitate of dark-red azo compound
was isolated by filtration and washed four times with water. Then the
dark-red azo compound was dissolved in 2-methoxyethanol (50 mL).
Copper(II) sulfate pentahydrate (6.0 g) in 15 mL of water and 24 mL
of 25% aqueous ammonium hydroxide solution were added with
stirring to the solution of the azo compound. Afer 2 h at 98°C, the
reaction mixture was cooled to room temperature. The suspension
was filtered and the residue was stirred with 20 mL of 5 N hydrochlo-
ric acid for 1 h. To the resulting acid mixture, 10 mL of water and
6 mL of 25% aqueous ammonium hydroxide solution were added (to
pH = 8). The crude precipitated product was isolated by filtration,
washed with water and dried. Three-fold crystallization from butyl
acetate afforded the substituted 5-aminobenzotriazole 4a–c as color-
less needles.
dine 4 × CH3), 1.61 (d, J = 7.1 Hz, 4H, piperidine 2 × CH2), 2.02 (br s,
1H, piperidine NH), 4.1 2(d, J = 7 Hz, 2H, allyl CH2), 5.13–5.30 (m, 1H,
piperidine CH), 7.09–7.13 (m, H, =CH-), 7.19 (d, J = 8 Hz, 2H, CH2 = ),
7.26–8.39 (m, 7H, ArH), 8.63 (br s, 1H, NH), 9.55 (br s, 1H, NH), 11.15 (br
s, 1H, OH); 13C NMR (acetone-d6), δ (ppm): 24.3, 44.9, 49.1, 59.6, 60.3,
103.8, 104.7, 118.1, 118.4, 119.7, 122.7, 124.7, 127.1, 130.9, 138.2, 140.5,
144.0, ESI-HRMS, m/z, (M+H+): Calcd 516.2826, observed 516.2835.
Anal. Calcd for C27H33N9O2: C, 62.89; H, 6.45; N, 24.45. Found: C, 63.01;
H, 6.38; N, 24.61.
2-[2-(2-Hydroxyphenyl)benzotriazol-5-amino]-4-allylamino-
6-(1,2,2,6,6-pentamethylpiperidin-4-yloxy)-s-triazine (5b)ꢀYield
1
63%; mp 235.2–236.9°C; H NMR (acetone-d6): δ 1.39 (s, 12H, piperi-
dine 4 × CH3), 1.54 (d, J = 7 Hz, 4H, piperidine 2 × CH2), 2.07 (s, 3H,
CH3-N), 4.07 (d, J = 7 Hz, 2H, allyl CH2), 4.11–4.33(m, 1H, piperidine
CH), 7.10–7.14 (m, H, =CH-), 7.19 (d, J = 8 Hz, 2H, CH2 = ), 7.39–8.35
(m, 7H, ArH), 8.62 (br s, 1H, NH), 9.63 (br s, 1H, NH), 11.14 (br s, 1H,
OH); FT-IR, ν/cm-1: 682, 750, 1247, 1491, 1583, 1660, 2925, 3677; ESI-
HRMS, m/z, (M+H+): Calcd 530.3029, observed 530.2992. Anal. Calcd
for C28H35N9O2: C, 63.50; H, 6.66; N, 23.80. Found: C, 63.34; H, 6.72; N,
23.86.
2-[2-(5-Methyl-2-hydroxyphenyl)benzotriazol-5-amino]-4-al-
lylamino-6-(2,2,6,6-tetramethylpiperidin-4-yloxy)-s-triazine
1
(5c)ꢀYield 70%; mp 221.3–224.5°C; H NMR (acetone-d6): δ 1.23 (s,
2-(5-Amino-2H-benzotriazol-2-yl)phenol (4a)ꢀYield 81%; mp
12H, piperidine 4 × CH3), 1.44 (d, J = 9 Hz, 4H, piperidine 2 × CH2),
2.05 (br s, 1H, piperidine NH), 2.83 (s, 3H, CH3), 4.09 (d, J = 7 Hz, 2H,
1
210.5–212.7°C (lit. mp 212–215°C [28]); H NMR (CDCl3): δ 4.02 (br s,
2H, NH2), 6.93–8.30 (m, 7H, ArH), 11.40 (br s, H, OH); ESI-HRMS, m/z, allyl CH2), 5.12–5.26 (m, 1H, piperidine CH), 7.09–7.14 (m, H, =CH-),
(M+H+): Calcd 227.0938, observed 227.0933). Anal. Calcd for C12H10N4O: 7.22 (d, J = 8 Hz, 2H, CH2 = ), 7.39–8.62 (m, 6H, ArH), 8.65 (br s, 1H, NH),
C, 63.71; H, 4.46; N, 24.76. Found: C, 63.67; H, 4.52; N, 24.81.
9.54 (br s, 1H, NH), 10.93 (br s, 1H, OH); FT-IR, ν/cm-1: 684, 814, 1246,
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 5/26/15 11:04 AM

ꢂꢁꢁꢁ
X. Gou et al.: Multifunctional hindered amine light stabilizersꢀ
ꢀ19
1284, 1511, 1663, 2858, 3614; ESI-HRMS, m/z, (M+H+): Calcd 530.3030, 2-[2-(2-Hydroxy-5-chlorophenyl)benzotriazol-5-amino]-4-al-
observed 530.2992. Anal. Calcd for C28H35N9O2: C, 63.50; H, 6.66; N, lylamino-6-(1,2,2,6,6-pentamethylpiperidin-4-yloxy)-s-triazine
1
23.80. Found: C, 63.58; H, 6.44; N, 23.73.
(5f)ꢀYield 62%; mp 267.3–270.7°C; H NMR (acetone-d6): δ 1.29 (s,
12H, piperidine 4 × CH3), 1.61 (d, J = 7.1 Hz, 4H, piperidine 2 × CH2),
2-[2-(5-Methyl-2-hydroxyphenyl)benzotriazol-5-amino]-4-al- 2.85 (s, 3H, CH3-N), 4.16 (d, OH); FT-IR, ν/cm-1: 713, 819, 1244, 1283,
lylamino-6-(1,2,2,6,6-pentamethylpiperidin-4-yloxy)-s-triazine 1504, 1658, 3274, 3676; ESI-HRMS, m/z, (M+H+): Calcd 564.2593,
1
(5d)ꢀYield 65%; mp 216.4–218.5°C; H NMR (acetone-d6): δ 1.23 (s, observed 564.2602. Anal. Calcd for C28H34N9O2Cl: C, 59.62; H, 6.08; N,
12H, piperidine 4 × CH3), 1.44 (d, J =9.1 Hz, 4H, piperidine 2 × CH2), 22.35. Found: C, 59.52; H, 6.13; N, 22.40.
2.05 (br s, 1H, piperidine NH), 2.83 (s, 3H, CH3), 4.09 (d, J = 7 Hz, 2H,
allyl CH2), 5.12–5.26 (m, 1H, piperidine CH), 7.09 (m, H, =CH-), 7.22
(d, J = 8.4 Hz, 2H, CH2 = ), 7.37–8.60 (m, 6H, ArH), 8.62 (br s, 1H, NH), General procedure for synthesis of polymers
9.54 (br s, 1H, NH), 10.93 (br s, 1H, OH); FT-IR, ν/cm-1: 684, 814, 1246,
poly(MMA-co-stabilizer 5a–f)
1284, 1511, 1663, 2858, 3614; ESI-HRMS, m/z, (M+H+): Calcd 544.3183,
observed 544.3148. Anal. Calcd for C29H37N9O2: C, 64.07; H, 6.86; N,
23.19. Found: C, 63.14; H, 6.72; N, 23.11.
The free-radical copolymerization of the monomeric stabilizers with
methyl methacrylate (MMA) was investigated [29, 30]. A solution of
MMA in toluene was added dropwise with stirring at 75°C to a mixture
of 1.0 wt.-% of the corresponding HALS monomer, 1.0 wt.-% of azobi-
sisobutyronitrile and 1.0 wt.-% of dibutyl phthalate (DBP) in a mixed
solvent toluene/tetrahydrofuran (Vtoluene:VTHF = 7:3). The resulting mix-
ture was polymerized for 8 h under a dry nitrogen atmosphere. This
process was controlled by TLC analysis until the filtrate was free of
monomer 5a–f. Then the precipitated copolymers poly(MMA-co-sta-
bilizer 5a–f) were repeatedly washed with methanol and dried under
reduced pressure to constant weight at room temperature.
2-[2-(2-Hydroxy-5-chlorophenyl)benzotriazol-5-amino]-4-al-
lylamino-6-(2,2,6,6-tetramethylpiperidin-4-yloxy)-s-triazine
(5e)ꢀYield 67.7%, mp 262.3–264.7°C. 1H NMR (acetone-d6): δ (ppm):
1.29 (s, 12H, piperidine 4 × CH3), 1.31 (d, J = 7 Hz, 4H, piperidine 2 ×
CH2), 2.01 (br s, 1H, piperidine NH), 4.31 (d, J = 7 Hz, 2H, allyl CH2),
5.12–5.24 (m, 1H, piperidine CH), 7.04 (m, H, =CH-), 7.21 (d, J = 9 Hz,
2H, CH2 = ), 7.42–8.34 (m, 6H, ArH), 8.62 (br s, 1H, NH), 9.57 (br s, 1H,
NH), 11.18 (br s, 1H, OH); FT-IR, ν/cm-1: 710, 817, 1244, 1283, 1505,
1658, 3272, 3676. ESI-HRMS, m/z, (M+H+): Calcd 550.2438, observed
550.2446. Anal. Calcd for C27H32N9O2Cl: C, 58.96; H, 5.86; N, 22.92. Received September 9, 2013; accepted November 10, 2013; previ-
Found: C, 59.06; H, 5.91; N, 23.03.
ously published online January 9, 2014
References
[1] Di, Z. C.; Lu, W. Z.; Wang, K. L.; Liang, J. Studies on UV
transparent characteristics of carbon nanotube filled LDPE films.
Chem. J. Chinese Univ. 2004, 25, 394–396.
[2] Butola, B. S.; Joshi, M. Photostability of HDPE filaments
stabilized with UV absorbers (UVA) and light stabilizers (HALS).
J. Eng. Fibers Fabrics 2013, 8, 61–68.
[3] Evans, P. D.; Kraushaar, G. S.; Liu, C. L.; Cullis, L.; Sebe, G.
Photostabilization of wood using low molecular weight phenol
formaldehyde resin and hindered amine light stabilizer. Polym.
Degrad. Stabil. 2013, 98, 158–168.
[4] Yang, Y. C.; Cheng, J.; Cheng, C. M.; He, J.; Guo, B. H.; Zhao,
Y. F. Design, synthesis and anti-oxidative evaluation of novel
anti-oxidant molecules in polyolefin. Chem. J. Chinese Univ.
2011, 32, 286–291.
[5] Chen, W.; An, P.; Chen, Y. X.; Li, Y.; Yan, X. L.; Chen, L. G.
Synthesis and light-stabilizing ability of a series of hindered
piperidine derivatives. Synth. Commun. 2012, 42, 1419–1425.
[6] Chai, R. D.; Chen, S. J.; Zhang, J. Combined effect of hindered amine
light stabilizer and ultraviolet absorbers on photodegradation
of poly(vinyl chloride). J. Vinyl Addit. Technol. 2012, 18, 17–25.
[7] Bojinov, V. B. Synthesis of novel bifunctional hindered amine-UV
absorber polymer stabilizers. Polym. Degrad. Stabil. 2006, 91,
128–135.
[8] Konstantinova, T.; Lazarova, R., Bojinov, V. On the
photostability of some naphthalimide dyes and their
copolymers with methyl methacrylate. Polym. Degrad. Stabil.
2003, 82, 115–118.
[9] Gryn’ova, G.; Ingold, K. U.; Coote, M. L. New insights into the
mechanism of amine/nitroxide cycling during the hindered
amine light stabilizer inhibited oxidative degradation of
polymers. J. Am. Chem. Soc. 2012, 134, 12979–12988.
[10] Hodgson, J. L.; Coote, M. L. Clarifying the mechanism of
the denisov cycle: how do hindered amine light stabilizers
protect polymer coatings from photo-oxidative degradation
macromolecules. Macromolecules 2010, 43, 4573–4583.
[11] Katritzky, A. R.; Zhang, S. M.; Wang, M. Y.; Kolb, H. C.; Steel,
P. J. Novel syntheses of polysubstituted pyrroles and oxazoles
by 1,3-dipolar cycloaddition reactions of benzotriazole-
stabilized nitrile ylides. J. Heterocycl. Chem. 2002, 39,
759–765.
[12] Kruczala, K.; Aris, W.; Schlick, S. Stabilization and early
degradation of UV-irradiated heterophasic propylene-ethylene
copolymers based on ESR, ESR imaging, UV-vis and DSC: effect
of ethylene content and UV wavelength. Macromolecules 2005,
38, 6979–6987.
[13] Liu, X. X.; Chen, Y. L. Reactive-HALS I: synthesis, charac-
terization, copolymerization reactivity and photo-stabilizing
performance applied in UV-curable coatings. Polym. Adv.
Techn. 2002, 13, 247–253.
[14] Cao, K.; Wu, S. L.; Qiu, S. L.; Li, Y.; Yao, Z. Synthesis of N-alkoxy
hindered amine containing silane as a multifunctional flame
retardant synergist and its application in intumescent flame
retardant polypropylene. Ind. Eng. Chem. Res. 2013, 52,
309–317.
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 5/26/15 11:04 AM

ꢁꢁꢁꢂ
ꢀX. Gou et al.: Multifunctional hindered amine light stabilizers
20ꢀ
[15] Wang, Z.; Ning, P. S.; Ding, Z. M. The research progress of
hindered amine light stabilizers. Plast. Addit. 2012, 1–9.
DOI: 10.3969/j.issn.1672-6294.2012.01.001.
[16] Bojinov, V. B., Grabchevb, I. Synthesis of new combined
2,2,6,6-tetramethylpiperidine 2-hydroxyphenylbenzotriazole
1,3,5-triazine derivatives as stabilizers for polymers. Polym.
Degrad. Stabil. 2001, 74, 543–550.
[17] Bojinov, V. Synthesis and properties of adducts of a hindered
amine and 2-hydroxyphenylbenzotriazole as novel polymer
stabilizers. Photochem. Photobiol. Sci. 2002, 1, 340–346.
[18] Bojinov, V. B., Simeonov, D. B. Synthesis of novel bifunctional
polymer stabilizers – a combination of HALS and UV absorber.
J. Photochem. Photobiol. A Chem. 2006, 180, 205–212.
[19] Bojinov, V. Synergistic efficiency of combined HALS-UV
absorber polymerizable stabilizers. J. Appl. Polym. Sci. 2006,
102, 2408–2415.
[23] Marc, G. C.; Mortsel, J. J.; Hove, W. J. UV-absorbing polymer
latex. Patent US 3761272, 1971.
[24] Liu, X.; Ju, C. X.; Hu, R. X.; Gu, D. P. Method of preparation of
4-hydroxy-1,2,2,6,6-pentamethylpiperidine. J. Hebei Normal
Univ. (Natural Sci. Edn.) 2006, 30, 326–328.
[25] Nakaya, F.; Noda, T.; Sakashita, K. Method of producing a
polymer using monomers having a piperidine skeleton and
molded body. Patent WO 2011068110, 2011.
[26] Ren, X. H.; Jiang, Z. M.; Li, R. Preparation of halamine
germicide for fabrics. Patent CN 102797150, 2012.
[27] Bojinov, V.; Konstantinova, T.; Konstantinov, H. Synthesis
and application of triazinyl-2,2,6,6-tetramethylpiperidine
derivatives as stabilizers for polymeric materials. Die Angew.
Makromol. Chem. 1998, 260, 17–20.
[28] Refat, M. S. Synthesis, spectroscopic characterization,
thermal, and photostability studies of 2-(2′-hydroxy-5′-phenyl)-
5-aminobenzotriazole complexes. J. Therm. Anal. Calorim.
2010, 102, 1095–1103.
[20] Evans, P. D.; Gibsonb, S. K.; Cullis, L.; Liu, C. L.; Sebe, G.
Photostabilization of wood using low molecular weight phenol
formaldehyde resin and hindered amine light stabilizer. Polym. [29] Ma, W.; Meng, M.; Jiang, X.; Tang, B. T.; Zhang, S. F. Synthesis
Degrad. Stabil. 2013, 98, 158–168.
of a water-soluble macromolecular light stabilizer containing
hindered amine structures. Chinese Chem. Lett. 2013, 24,
153–155.
[21] Therias, S. Y.; Mailhot, B.; Gonzalez, D.; Gardette, J. L. Photoox-
idation of polypropylene/montmorillonite nanocomposites.
Chem. Mater. 2005, 17, 1072–1078.
[22] Bojinov, V.; Grabchev, I. Synthesis and properties of new
adducts of 2,2,6,6-tetramethylpiperidine and 2-hydroxyphe-
nylbenzotriazole as polymer photostabilizers. J. Photochem.
Photobiol. A 2002, 150, 223–231.
[30] Taguchi, Y.; Ishida, Y.; Ohtani, H.; Matsubara, H. Direct
analysis of an oligomeric hindered amine light stabilizer in
polypropylene materials by MALDI-MS using a solid sampling
technique to study its photostabilizing action. Anal. Chem.
2004, 76, 697–703.
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 5/26/15 11:04 AM