While Δ⁹‐tetrahydrocannabinolic acid A (THCA‐A) has been reported to be difficult to crystallize and/or amorphous, we have obtained THCA‐A in a pure crystalline form by extraction of marijuana and selective fractionation with liquid CO₂. THCA‐A (systematic name: 1‐hydroxy‐6,6,9‐trimethyl‐3‐pentyl‐6a,7,8,10a‐tetrahydro‐6H‐benzo[c]isochromene‐2‐carboxylic acid, C₂₂H₃₀O₄) crystallizes in the orthorhombic space group P2₁2₁2₁, with Z = 8 and Z′ = 2. The two independent molecules are related by a pseudo‐twofold axis centered between the two –CO₂H groups, but the conformations of the two –C₅H₁₁ chains are quite different (tgt and ttg; t is trans and g is gauche). The carboxylate groups form an intermolecular R₂²(8) hydrogen‐bonded ring; the two C₂O₂ carboxylate planes are twisted out of the planes of the attached arene rings in opposite directions by 13.59 (8) and 18.92 (8)°, respectively, with a resultant interplanar angle of 28.89 (8)°. Each molecule also has an intramolecular S(6) hydrogen‐bond motif between the ortho –OH group and the dihydropyran‐ring O atom. Other conformational aspects of the two independent molecules are quite similar to those found in the previously determined structure of THCA‐B. THCA‐A has shown promise in a number of medical applications. Demonstration of the crystallinity and details of the crystal structure are expected to provide a standard point of departure for chemical and medical experiments.

中文翻译：

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Δ9-四氢大麻酚A，Δ9-四氢大麻酚（THC）的前体

而Δ ⁹ -tetrahydrocannabinolic酸A（THCA-A）已被报道为难以结晶和/或无定形的，我们已经在纯结晶形式通过大麻和选择性分馏的提取用液体CO获得THCA-A ₂。THCA‐A（系统名称：1‐羟基‐6,6,9‐三甲基‐3‐戊基‐6a，7,8,10a‐四氢‐6 H‐苯并[ c ]异亚甲基-2-羧酸，C ₂₂ H ₃₀ O ₄）在正交空间群P 2 ₁ 2 ₁ 2 _1中结晶，Z  = 8，Z' =2。两个独立的分子通过位于两个–CO ₂ H基团之间的假双倍轴关联，但是，两个–C ₅ H ₁₁链的构象完全不同（tgt和ttg；t为反式和g是gauche）。羧酸根形成分子间的R ₂ ²（8）氢键环；两个C ₂ O ₂羧酸盐平面以相反的方向分别以13.59（8）和18.92（8）°的方向从连接的芳烃环的平面中扭曲出来，从而产生了28.89（8）°的平面角。每个分子在邻-OH基团与二氢吡喃环O原子之间还具有分子内S（6）氢键基序。这两个独立分子的其他构象方面与先前确定的THCA-B结构中的构象方面非常相似。THCA‐A在许多医疗应用中都显示出了希望。结晶度的证明和晶体结构的细节有望为化学和医学实验提供一个标准出发点。