tert-Butyl­aminium 2-carb­oxy-4,5-dichloro­benzoate

Graham Smith; Urs D Wermuth

doi:10.1107/S1600536811034131

. 2011 Aug 27;67(Pt 9):o2461. doi: 10.1107/S1600536811034131

tert-Butylaminium 2-carboxy-4,5-dichlorobenzoate

Graham Smith ^a,^*, Urs D Wermuth ^a

PMCID: PMC3200858 PMID: 22064684

Abstract

In the structure of the title anhydrous salt, C₄H₁₂N⁺·C₈H₃Cl₂O₄ ⁻, the 4,5-dichlorophthalate monoanions have the common ‘planar’ conformation with the carboxyl groups close to coplanar with the benzene ring and with a short intramolecular carboxylic acid O—H⋯O hydrogen bond. In the crystal, a two-dimensional sheet structure is formed through aminium N—H⋯O_carboxyl hydrogen-bonding associations.

Related literature

For structures of 1:1 salts of 4,5-dichlorophthalic acid with acyclic aliphatic amines, see: Mattes & Dorau (1986 ▶); Bozkurt et al. (2006 ▶); Smith & Wermuth (2010a ▶,b ▶,c ▶).

Experimental

Crystal data

C₄H₁₂N⁺·C₈H₃Cl₂O₄ ⁻
M _r = 308.15
Monoclinic,
a = 6.1778 (2) Å
b = 12.7158 (4) Å
c = 17.7125 (7) Å
β = 96.784 (4)°
V = 1381.68 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.48 mm⁻¹
T = 200 K
0.45 × 0.26 × 0.18 mm

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010 ▶) T _min = 0.977, T _max = 0.990
8677 measured reflections
2719 independent reflections
2307 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.094
S = 0.90
2719 reflections
188 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2010 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) within WinGX (Farrugia, 1999 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: PLATON.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811034131/bt5620sup1.cif

e-67-o2461-sup1.cif^{(18.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811034131/bt5620Isup2.hkl

e-67-o2461-Isup2.hkl^{(130.8KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811034131/bt5620Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1A—H11A⋯O21	0.89 (2)	2.02 (2)	2.883 (2)	164 (2)
N1A—H12A⋯O11ⁱ	0.91 (2)	1.88 (2)	2.784 (2)	174 (2)
N1A—H13A⋯O12ⁱⁱ	0.89 (2)	1.99 (2)	2.861 (2)	167 (2)
O21—H21⋯O12	0.94 (4)	1.47 (4)	2.4021 (19)	173 (4)

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The authors acknowledge financial support from the Australian Research Council and the Faculty of Science and Technology and the University Library, Queensland University of Technology.

supplementary crystallographic information

Comment

4,5-Dichlorophthalic acid (DCPA) commonly forms 1:1 salts with the acyclic aliphatic amine analogues and with these, low-dimensional hydrogen-bonded structures are usually found, featuring the 'planar' hydrogen phthalate anion e.g with isopropylamine (Smith & Wermuth, 2010a), diisopropylamine (Smith & Wermuth, 2010b), diethylamine, triethylamine and n-butylamine (Smith & Wermuth, 2010c), the ammonium and tetra(nbutyl)ammonium salts (Mattes & Dorau, 1986) and the tetramethylammonium salt (Bozkurt et al., 2006). Our 1:1 stoichiometric reaction of DCPA with t-butylamine also gave a 1:1 salt C₄H₁₂N⁺ C₈H₃Cl₂O₄^-, the title compound and the structure is reported here.

In this structure the common 'planar' DCPA anion is found (Fig. 1) and has the previously described (Smith & Wermuth, 2010c) short intramolecular carboxylic acid O—H···O_carboxy hydrogen bond (Table 1) (torsion angles C1–C2–C21–O22 and C2–C1–C11–O11: 176.59 (18) and 175.26 (17) Å respectively). Other structural features common to this 'planar' monoanion are a lengthening of the C1—C11 and C2—C21 bond lengths [1.522 (2) and 1.528 (3) Å] and distortion of the external bond angles at C1 and C2 [C1—C2—C21, 129.57 (15)° and C2—C1—C11, 128.84 (15)°].

Intermolecular aminium N—H···O(carboxyl) hydrogen bonds (Table 1) link the DCPA monoanions across b as well as down the a axis, forming a two-dimensional sheet structure (Fig. 2).

Experimental

The title compound was synthesized by heating together for 10 min under reflux, 1 mmol quantities of 4,5-dichlorophthalic acid and t-butylamine in 50 ml of 50% ethanol–water. Partial evaporation of the solvent gave colourless crystalline plates from which a specimen was cleaved for the X-ray analysis..