Synthesis and performance of N-(benzoyl)stearic acid hydrazide

Article abstract of DOI:10.1155/2012/514386

N-(benzoyl) stearic acid hydrazide was synthesized from benzoyl hydrazine and stearyl chloride which was deprived from stearic acid via acylation.The structure of the compound had been characterized byFT-IR, 1H NMR, at the same time, the structure of N-(benzoyl) stearic acid hydrazide was optimized by the semiempirical method PM3. The influence of the reaction ratio, reaction time and reaction temperature to the yield of N-(benzoyl) stearic acid hydrazidewas investigated by orthogonal experiment, and the optimized reaction condition was molar ratio of benzoyl hydrazine: stearyl chloride 1:1, reaction time 6 h, reaction temperature 70°, and the yield was 92.9%. The TGAthermalanalysisof N-(benzoyl) stearic acid hydrazideshowed that thermal stability of N-(benzoyl) stearic acid hydrazide was affected by heating rate, and the N-(benzoyl) stearic acid hydrazideenhanced the tensile strength, modulus and elongation at break of Poly (L-lactic acid) (PLLA).

Full text of DOI:10.1155/2012/514386

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
http://www.ejchem.net
2012, 9(2), 545-552
Synthesis and Performance of
N-(Benzoyl) Stearic Acid Hydrazide
YAN-HUA CAI* and SHUN-JIANG LI
School of Materials and Chemical Engineering,
Chongqing University of Arts and Sciences,
Yongchuan, Chongqing-402160, P.R. China
caiyh651@yahoo.com.cn
Received 21 March 2011; Revised 18 August 2011; Accepted 4 September 2011
Abstract: N-(benzoyl) stearic acid hydrazide was synthesized from benzoyl
hydrazine and stearyl chloride which was deprived from stearic acid via
acylation. The structure of the compound had been characterized by FT-IR,
1H NMR, at the same time, the structure of N-(benzoyl) stearic acid hydrazide
was optimized by the semiempirical method PM3. The influence of the
reaction ratio, reaction time and reaction temperature to the yield of
N-(benzoyl) stearic acid hydrazide was investigated by orthogonal
experiment, and the optimized reaction condition was molar ratio of benzoyl
hydrazine: stearyl chloride 1:1, reaction time 6 h, reaction temperature 70 ℃,
and the yield was 92.9%. The TGA thermal analysis of N-(benzoyl) stearic
acid hydrazide showed that thermal stability of N-(benzoyl) stearic acid
hydrazide was affected by heating rate, and the N-(benzoyl) stearic acid
hydrazide enhanced the tensile strength, modulus and elongation at break of
Poly(L-lactic acid)(PLLA).
Keywords: Stearic acid, Benzoyl hydrazine, Poly(L-lactic acid), Orthogonal experiment.
Introduction
With the increasing development of science and technology, amides, as a kind of very
important organic compound, has a wider application fields. Besides the traditional fields of
synthetic intermediates1,2, material chemistry3,4, amides play an active role in drug
discovery5, polymer6-8, etc and obtained a lot of progress. For example, the importance of
the amides in polymer has been recently highlighted by Cai and co-workers6. In that article,
N,N'-bis(benzoyl) suberic acid dihydrazide as heterogeneous nucleation agent can
significantly improve the crystallization of poly(L-lactic acid)(PLLA). N,N'-bis(benzoyl)
suberic acid dihydrazide leads to the shift of the melt crystallization to higher temperature
and becomes much sharper in the melting crystallization process of PLLA. Upon the addition
of 0.8% N,N'-bis(benzoyl) suberic acid dihydrazide, the crystallization half-time of PLLA/
N,N'-bis(benzoyl) suberic acid dihydrazide decreases from 26.5 min to 1.4 min at 115 ℃.

546 YAN-HUA CAI et al.
Furthermore, Angela and co-workers8 also reported that ethylene bis- stearamide can serve
as a nucleating agent of PLLA for dramatic increasing in crystallization rate and final
crystalline content as indicated by isothermal and nonisothermal crystallization
measurements. Thus, amide will play more important role in industry and agriculture.
In order to further develop the more amide compounds, and adequately investigate the
performance of amide compounds. In this study, N-(benzoyl) stearic acid hydrazide was
synthesized from benzoyl hydrazine and stearyl chloride which was deprived from stearic
acid via acylation. The influence of the reaction conditions to the yield and thermal stability
of product was investigated by orthogonal experiment and TGA respectively. Finally, the
effection of N-(benzoyl) stearic acid hydrazide towards PLLA’s mechanical properties were
further investigated.
Experimental
The materials used in this study were of analytical grade (AR). Benzoyl hydrazine and
stearic acid were procured from Chengdu Kelong Chemical Reagents Company respectively
(Sichuan Province, China); Thionyl dichloride, N, N-dimethylacetamide and Pyridine were
procured from Mianyang Rongshen Chemical Reagents Company (Sichuan Province,
China). poly(L-lactic acid)(PLLA) was purchased from Nature Works LLC, USA.
Synthesis procedure of N-(benzoyl) stearic acid hydrazide
N-(benzoyl) stearic acid hydrazide was prepared as shown in Scheme 1: stearic acid and
thionyl dichloride of 50 mL was mixed in the presence of N,N-dimethylacetamide as
catalyst. Then the mixture was heated up to 80 ℃ and held at 80 ℃ with stirring for 7 h.
After cooling to room temperature and evaporation of thionyl dichloride in vacuum, the
residue was stearyl chloride.
Benzoic hydrazide and N,N-dimethylacetamide of 50 mL were mixed and the mixture
was purged under nitrogen atmosphere. Stearyl chloride was added slowly onto the mixture,
followed by adding pyridine of 0.057 mol, then the mixture was heated up to 60～ 80 ℃ and
held at 60～ 80 ℃ for period of time with stirring. The reaction mixture was poured onto
water of 250 mL and stirred, followed by filtrating. Obtained crude product was washed four
times by water of each 250 mL at room temperature, and then washed by methanol of
200 mL at 50 ℃ to eliminate raw materials and by-products, the resulting product was dried
in a vacuum at 55 ℃.
O
O
DMF
+
HCl
+
SO2
Cl
+
OH
SOCl2
C
O
D
HN
M
F
NH2
O H
O
N N C
H
Scheme 1. Synthesis of N-(benzoyl) stearic acid hydrazide.

Synthesis and Performance of N-(Benzoyl) Stearic 547
Preparation of PLLA/N-(benzoyl) stearic acid hydrazide samples
PLLA was dried overnight at 50 ℃ under vacuum to remove residual water. Blending of
PLLA and dried N-benzoyl stearic acid hydrazide was performed on a counter-rotating
mixer with a rotation speed of 32 rpm for 5min, then at 64 rpm for 5 min. The processing
temperature was set at 185 ℃. Products were hot pressed at 180 ℃ under 20 MPa for 3
min to prepare sheets with a thickness of approximately 0.4 mm. The sheets were then
cooled down to room temperature by being compressed at room temperature under
20 MPa for 10 min.
Results and Discussion
Structure of N-(benzoyl) stearic acid hydrazide
The FT-IR spectra of N-(benzoyl) stearic acid hydrazide is shown in Figure 1. As showen in
the spectra, the peak at 3400 cm-1 contributes to the absorption of N-H stretching vibration;
the absorption peaks at 2917.6 cm-1, 2849 cm-1 and 716.7 cm-1 contribute to CH2
symmetrical stretching vibration, asymmetrical stretching vibration and rocking vibration
respectively. Owing to conjugated effect, C=O of benzoic hydrazide moves to lower
vibrational frequency. That’s to say, the absorption peak at 1638.1 cm-1 contributes to C=O
stretching vibration, and the absorption peak at 1666.7 cm-1 contributes to C=O of amide.
Then the absorption peaks at 1602.2 cm-1, 1572.7 cm-1, 1500 cm-1, and 1469.2 cm-1 prove the
existence of benzene.
Wavenumber/cm-1
Figure 1. FT-IR spectra of N-(benzoyl) stearic acid hydrazide.
1
The H NMR patterns of N-(benzoyl) stearic acid hydrazide is depicted in Figure 2.
The single peak at δH=10.27 and 9.82 are proton resonance peak of N-H of N-(benzoyl)
stearic acid hydrazide, the multiple peaks at δH=7.47-7.88 are proton resonance peaks of
benzene, the triplet peaks at δH=2.15-2.18 are CH2 which is near amide proton resonance
peak. As for the multiple peaks at δH=1.24-1.56, they belong to other CH2 proton resonance
peaks, the triplet peaks at δH=0.84-0.86 are CH3 proton resonance peaks. NMR analysis
further confirms that N-(benzoyl) stearic acid hydrazide was synthesized.

548 YAN-HUA CAI et al.
Figure 2. 1H NMR spectra of N-(benzoyl) stearic acid hydrazide.
In order to further investigate the structure of N-(benzoyl) stearic acid hydrazide, the
optimized geometric structure of N-(benzoyl) stearic acid hydrazide was carried out by the
theoretical calculation which were performed by the program VAMP using the
semiempirical method PM3. The optimized geometry structure of N-(benzoyl) stearic acid
hydrazide is shown in Figure 3 and the HOMO and LUMO of phthalimide is -9.852 eV and
-0.309 eV, respectively.
Figure 3. Optimized geometric structure, HOMO and LUMO of N-(benzoyl) stearic acid
hydrazide.

Synthesis and Performance of N-(Benzoyl) Stearic 549
Synthesis conditions of N-(benzoyl) stearic acid hydrazide
The influence of the reaction ratio, reaction time and reaction temperature to the yield of
product was investigated by orthogonal experiment. Factors and levels of orthogonal
experiment are listed in Table 1 and the results are listed in Table 2. As seen in Table 2. It is
clear that reaction time is more important to yield than other factors. The reason is that the
high reactivity of stearyl chloride can result in shorter reaction time, which lower the side
effects greatly. And the optimized reaction condition are as follows: molar ratio of benzoyl
hydrazine: stearyl chloride 1:1, reaction time 6 h, reaction temperature 70 ℃, and the yield
is 92.9 %.
Table 1. Factors and levels of orthogonal experiment.
Factor
Level
Reaction time (A)
Reaction ratio(a)(B)
Reaction temperature(C)
1
2
3
4 h
6 h
8 h
1:1
2:3
1:2
60 ℃
70 ℃
80 ℃
(a) Benzoic hydrazide: stearyl chloride.
Table 2. Results of orthogonal experiment.
Run
A
1
B
1
C
Scheme Yield/%
1
1
A1B1C1
A1B2C2
A1B3C3
A2B2C3
A2B3C1
A2B1C2
A3B3C2
A3B1C3
A3B2C1
77
2
1
2
2
3
80.4
81.7
72.1
82.2
92.9
70.4
73.4
61.8
3
1
3
4
2
2
3
5
2
3
1
6
2
1
2
7
3
3
2
8
3
1
3
9
3
2
1
K1
K2
2.09
2.17
1.76
0.41
2.13
1.84
2.04
0.29
1.91
2.14
1.98
0.23
A B C
K3
Extreme difference
Important factor
Optimized scheme
A2 B1 C2
Thermal decomposition of N-(benzoyl) stearic acid hydrazide
Thermal stability is very important for application of N-(benzoyl) stearic acid hydrazide,
thus, the thermal stability of N-(benzoyl) stearic acid hydrazide was investigated by TGA.
Figure 4 shows the TGA curves of N-(benzoyl) stearic acid hydrazide with a heating ramp
of 2.5, 5, 10, 20, 30 ℃/min from room temperature to 500 ℃ under nitrogen flow. As seen

550 YAN-HUA CAI et al.
in Figure 4, N-(benzoyl) stearic acid hydrazide begins to decomposition above 185 ℃,
which suggests that N-(benzoyl) stearic acid hydrazide has good thermal stability in daily
application. After that, N-(benzoyl) stearic acid hydrazide decomposes fast and completely
in one stage above 200 ℃ at all heating rates. Furthermore, with the increasing of heating
rate, the decomposition temperature increases and heating decomposition degree decreases.
Rapid heating rate makes the decomposition of N-(benzoyl) stearic acid hydrazide not
achieve at set temperature, at the same time, the temperature has get into the following set
temperature, resulting in decomposition achieving at higher temperature.
Temperature/oC
Figure 4. TGA curves of N-(benzoyl) stearic acid hydrazide.
Mechanical properties of PLLA/N-(benzoyl) stearic acid hydrazide samples
Dumbbell-shaped tensile test specimens with effective dimensions of 25 mm×6 mm×1.0 mm
were prepared by pneumatic-controlled impact shaping machine. Tensile tests were
conducted on a D&G DX-10000 electronic tensile tester at the speed of 50 mm/min at room
temperature. The tensile strength, elastic modulus and elongation at break were obtained by
averaging over five specimens. The tensile strength, tensile modulus and elongation at break
of PLLA with different N-(benzoyl) stearic acid hydrazide contents are presented in Figure
5(a), Figure 5(b) and Figure 5(c), respectively. The figure shows that N-(benzoyl) stearic
acid hydrazide can improve the tensile strength, tensile modulus and elongation at break of
PLLA and the tensile strength, tensile modulus and elongation at break increase with the
increase of N-(benzoyl) stearic acid hydrazide contents and possesses a maximum value for
the critical N-(benzoyl) stearic acid hydrazide loading 0.5%, 0.8% and 0.3%, respectively.
Upon addition of optimized content of N-(benzoyl) stearic acid hydrazide, comparing with
the neat PLLA, the tensile strength, tensile modulus and elongations at break of PLLA/
N-(benzoyl) stearic acid hydrazide increase from 74.4 MPa, 3592.8 MPa, 2.72% to 81.3
Mpa, 4328.7 Mpa and 3.3%, respectively. Low N-(benzoyl) stearic acid hydrazide contents
in PLLA maybe existe a good dispersion and compatibility.

Synthesis and Performance of N-(Benzoyl) Stearic 551
Content/%
Content/%
Content/%
Figure 5. The mechanical properties of PLLA with different N-(benzoyl) stearic acid
hydrazide contents.
Conclusion
N-(benzoyl) stearic acid hydrazide was synthesized from benzoyl hydrazine and stearyl
chloride which was deprived from stearic acid via acylation. The optimum reaction
conditions were determined by orthogonal experiment as follows: molar ratio of benzoyl
hydrazine to stearyl chloride 1:1, reaction time 6 h, reaction temperature 70 ℃ and the yield
was 92.9 %. TGA results indicated good thermal stability of N-(benzoyl) stearic acid
hydrazide, and thermal stability was affected by heating rate. Besides, the N-(benzoyl)
stearic acid hydrazide enhanced tensile strength, modulus and elongation at break of PLLA.
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