Universal Set of Dyes for Digital Inkjet Textile Printing

NTC Project C03-PH01
6
mono-functional aldehyde, 9-anthraldehyde, in combination with methylamine, were reacted
under similar conditions. Although the one-pot process was attractive for use in combinatorial
syntheses, excessive reaction time [72-96 hours], and production of toxic hydrogen cyanide gas
as a by-product, made this synthetic route undesirable.
H 3C
N
O
H
H
HN
CH 3
H
NaBH 3 CN
CH 2
CH 3
CH 2
boroxin
CH3CN
K 2 CO 3
Reflux
B(OH) 2
C
H 2
N
Scheme 4. One-step reductive amination using the cyanoborohydride followed by a reaction
with boronic acid anhydride.
A one-step reductive amination reaction conducted using triacetoxyborohydride provided a safer
alternative, Scheme 5 [11]. The reducing agent converted stoichiometric amounts of the
dicarboxaldehyde and 1 º amine (methyl amine or α-methylbenzylamine) to the corresponding 2 º
amines in high yields, requiring a much shorter reaction time [20 min.- 2 hr.], while producing
only small amounts of benign by-products. Due to the high reactivity of the free amines, an
oxygen-free environment was required throughout the reduction reaction. Stable ammonium
chloride salts were isolated, and purification and characterization are currently being carried out.
It was anticipated that, by maintaining an oxygen-free environment, the reaction with 2,4,6-
tris[o-(bromomethyl)phenyl] boroxine can be conducted immediately following the reductive
amination without the HCl salt formation.
CH 3
H 3C
Ph
Ph
CH
N
H
O
H
H
CH
HN
CH 2
H 3C
Ph
CH
N
H 2
C
(HO) 2B
H
HB(OAc) 3 Na
DCE
H 2C
boroxin
CH3CN
K 2 CO 3
Reflux
CH 2
B(OH) 2
C
H 2
H 2C
N
Ph
CH
CH 3
H
H
O
N
Ph
Amine
NH
CH
CH 3
Ph CH 3
Scheme 5. One-step reductive amination using the triacetoxyborohydride followed by a reaction
with boronic acid anhydride.
Computationally in the third year we focused on studies designed to elucidate the
thermochemistry of the reaction between phenylboronic acid (PBA) and a sinple model
cellulosic substrate. The initial model of cellulose chosen for this study, C 1 , was a singlestranded
molecule composed of four repeating anhydroglucose units. The structure of this
molecule was optimized using density functional theory (DFT) at the LDA/6-31G* (B3LYP/6-
31G*) computational levels with the Spartan software package from Wavefunction Inc. [12], see
Figure 2. The initial geometry for the optimization was chosen to incorporate the expected
intramolecular hydrogen bonding [13], whereas intermolecular hydrogen bonding between
different strands in cellulose was completely ignored in these investigations.
National Textile Center Annual Report: November 2006