A deeper shade of green: inspiring sustainable drug manufacturing

Green and sustainable drug manufacturing go hand in hand with forward-looking visions seeking to balance the long-term sustainability of business, society, and the environment. However, a lack of harmonization among available metrics has inhibited opportunities for green chemistry in industry. Moreover, inconsistent starting points for analysis and neglected complexities for diverse manufacturing processes have made developing objective goals a challenge. Herein we put forward a practical strategy to overcome these barriers using data from in-depth analysis of 46 drug manufacturing processes from nine large pharmaceutical firms, and propose the Green Aspiration Level as metric of choice to enable the critically needed consistency in smart green manufacturing goals. In addition, we quantify the importance of green chemistry in the often overlooked, yet enormously impactful, outsourced portion of the supply chain, and introduce the Green Scorecard as a value added sustainability communication tool.

http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C6GC02901A?utm_medium=email&utm_campaign=pub-GC-vol-19-issue-1&utm_source=toc-alert#!divAbstract

The Green Aspiration Level (GAL) has been constructed on four pillars to ensure consistent application, namely (1) clearly defined synthesis starting points,1 (2) unambiguous complete E factor (cEF)2,3 or Process Mass Intensity (PMI) waste metrics, (3) historical averages of industrial drug manufacturing waste, and (4) complexity of the drug’s ideal manufacturing process (Supplementary Figure 6). cEF or PMI can be used interchangeably in GAL-based analysis enabling organizations using either to calculate their green performance scores. cEF and PMI differ by just one unit (Supplementary Equation 6) and share the same commercial waste goal for an average manufacturing step4 – the transformation-GAL or tGAL – that results in negligible numerical differences from the inclusion of one or the other. The pharmaceutical industry has generally adopted PMI. However, our publication utilizes cEF values due to literature prevalence and potentially broader appeal of E factors.5 It is important to note that all reaction and workup materials are included in the analysis, but excluded are reactor cleaning6 and solvent recycling.7 Standardized process starting points are a critical component of the GAL methodology. A starting material for some may be an intermediate for others. Until recently, the scientific community lacked an unambiguous definition of process starting points in the assessment of process greenness. This has been a bothersome source of inconsistency. Failure to define an appropriate starting material can lead to exclusion of significant amounts of intrinsic raw material waste created during earlier stages of manufacture. We therefore utilize these updated definitions of process analysis starting points to ensuring higher quality of data:8

1) The material is commercially available from a major reputable chemical laboratory catalog company, and its price is listed in the (online) catalog. Materials requiring bulk or custom quotes do not qualify as process starting material. AND 2) The laboratory catalog cost of the material at its largest offered quantity does not exceed US $100/mol. Therefore, published literature must be researched if the material does not qualify as process starting material in order to determine its correct intrinsic cEF. However, we realized that determination of literature cEF values is tedious and involves making assumptions since literature procedures are often incomplete compared to internal or external manufacturing batch records. Thus, standardizing Literature cEF quickly became a desirable goal. In order to facilitate literature analysis we introduced Supplementary Equation 7 that just requires determination of literature step count from ≤$100/mol starting materials without having to retrieve literature waste information.9 The literature step multiplier of 37 kg/kg represents the average literature step cEF across the analyzed projects (Supplementary Table 1), so it equals their average literature cEF (76 kg/kg) divided by average literature step count (2.1). The process cEF and Relative Process Greenness (RPG) derived from the simplified calculated cEF literature values are shown next to their progenitors in Supplementary Table 3. We observe that average calculated and manually determined cEF and RPG values are comparable and within 10% of their means across the three development phases. Thus, we consider the simplified method sound and an importtant element to achieving consistency in green process analysis.

Frank Roschangar,*^a   Juan Colberg,^b   Peter J. Dunn,^c  Fabrice Gallou,^d   John D. Hayler,^e   Stefan G. Koenig,^f  Michael E. Kopach,^g   David K. Leahy,^h  Ingrid Mergelsberg,ⁱ   John L. Tucker,^j  Roger A. Sheldon^kl and   Chris H. Senanayake^a  

 *Corresponding authors

^aChemical Development, Boehringer Ingelheim Pharmaceuticals, Ridgefield, USA
E-mail: frank.roschangar@boehringer-ingelheim.com

^bPharmaceutical Sciences – Worldwide Research & Development, Pfizer, Groton, USA

^cPfizer, Sandwich, UK

^dChemical & Analytical Development, Novartis Pharma, 4002 Basel, Switzerland

^eAPI Chemistry, GlaxoSmithKline Medicines Research Centre, Stevenage, UK

^fSmall Molecule Process Chemistry, Genentech, a Member of the Roche Group, South San Francisco, USA

^gSmall Molecule Design and Development, Eli Lilly and Company, Indianapolis, USA

^hChemical and Synthetic Development, Bristol-Myers Squibb, New Brunswick, USA

ⁱProcess Chemistry, Merck, Rahway, New Jersey 07065, USA

^jProcess Development, Amgen, Thousand Oaks, USA

^kMolecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa

^lDelft University of Technology, 2628 BL Delft, Netherlands

Green Chem., 2017,19, 281-285

DOI: 10.1039/C6GC02901A

Frank Roschangar, PhD MBA

Pharmaceutical process research director, passionate about accelerating drug development and driving green chemistry.

Boehringer Ingelheim

Research and Development Sites

Ingelheim am Rhein, Germany

Research experience

• Feb 2002–Sep 2015
   Director
  Boehringer Ingelheim
  Germany · Nieder-Ingelheim
• Aug 1996–Feb 1998

  Postdoc

  The Scripps Research Institute · Skaggs Institute for Chemical Biology · Prof. K.C. Nicolaou
  United States · La Jolla
• Aug 1992–Aug 1996

  PhD Candidate

  Rice University · Department of Chemistry
  United States · Houston

Supplementary References

1. The $100 per mol laboratory catalog pricing requirement described in Supplementary Discussion 1 does not apply to reagents, catalysts, ligands, and solvents, since they are produced for widespread application and are not specific to the process being evaluated.

2. Since the original E factor has been applied inconsistently, the cEF metric was introduced for the purpose of GAL analysis. cEF accounts for all process reaction and process workup materials, including raw materials, intermediates, reagents, process aids, solvents, and water.

3. All E factors reported herein represent the cEF or sEF contributions of the overall manufacturing process or the sub-process (e.g. external cEF, literature cEF) to produce 1 kg of drug substance.

4. We define a step as a chemical operation involving one or more chemical transformations that form and/or break covalent or ionic bonds and lead to a stable and isolable intermediate, but not necessarily include its isolation. Examples: • Simultaneous removal of two or more protection groups involves multiple transformations, yet it is carried out in one chemical operation  counted as one step • Sequential transformations via a stable and isolable intermediate that are carried out in two operations but without intermediate workup  counted as two steps • Formation of covalent bonds or salts that occur during workup  not counted as an extra step • Separate operation of salt formation from an isolated intermediate  counted as one step • Isolation of a product, following work-up, as a solution that can be stored  counted as one step.

5. A SciFinder search for the terms ‘Process Mass Intensity’, and ‘E factor’ and ‘Environmental impact factor’ on Nov. 14, 2016 revealed that the PMI concept was present in 12, 8, 9, and 12 publications for the years 2013-2016, respectively, while the E factor concept was mentioned 39, 45, 57, and 46 times (76-86%), respectively.

6. The GAL considers only direct process materials, i.e. materials used in the chemical steps and their workups. It does not include solvents and aqueous detergents required for reactor and equipment cleaning between batches or steps, nor the frequency and duration of the equipment and facility specific cleaning operations. These parameters are considered for comprehensive environmental impact in Life Cycle Assessment (LCA) analysis.

7. In US pharmaceutical manufacturing, recycling accounts for 25% of waste handling, while energy recovery burning and treatment constitute 38% and 35%, based on 2012 data from ‘The Right-To-Know Network’ (RTKNET.ORG), Toxic Releases (TRI) Database: http://rtknet.org/db/tri.

8. The $100 per mol commodity pricing criterion was established in ref. 15 of the main article based on the author’s professional experience. The authors of this manuscript consider this figure appropriate and helpful for providing a consistent analysis.

9. If a detailed procedure is available for a particular literature step, its calculated waste can be used in place of the 37 kg/kg default value.

10. J. Li and M. D. Eastgate, Current Complexity: a Tool for Assessing the Complexity of Organic Molecules. Org. Biomol. Chem. 2015,13, 7164–7176.

11. D. P. Kjell, I. A. Watson, C. N. Wolfe and J. T. Spitler, Complexity-Based Metric for Process Mass Intensity in the Pharmaceutical Industry. Org. Process Res. Dev. 2013, 17, 169– 174.

12. R. P. Sheridan, et al., Modeling a Crowdsourcing Definition of Molecular Complexity. J. Chem. Inf. Model. 2014, 54, 1604–1616.

13. M. F. Faul, et al., Part 2: Designation and Justification of API Starting Materials: Current Practices across Member Companies of the IQ Consortium. Org. Process Res. Dev. 2014, 18, 594–600.

14. Besides offering simplicity, the GAL’s process complexity model was selected vs. the alternative structural complexity measures due to its inherent ideality-derived consideration for available synthetic methodology.

15. See main article ref. 16: it defines Construction Reactions (CR) as chemical transformations that form skeletal C-C or C-heteroatom bonds. Strategic Redox Reactions (SRR) are construction reactions that directly establish the correct functionality found in the final product, and include asymmetric reductions or oxidations. All other types of non-strategic reactions are considered as Concession Steps (CS), and include functional group interconversions, non-strategic redox reactions, and protecting group manipulations.

16. M. E. Kopach, et al., Process Development and Pilot-Plant Synthesis of (2-Chlorophenyl)[2-(phenylsulfonyl)pyridin-3- yl]methanone. Org. Process Res. Dev. 2010, 14, 1229–1238.

17. M. E. Kopach, M. M. Murray, T. M. Braden, M. E. Kobierski, O. L. Williams, Improved Synthesis of 1-(Azidomethyl)-3,5-bis- (trifluoromethyl)benzene: Development of Batch and Microflow Azide Processes. Org. Process Res. Dev. 2009, 13, 152–160. 18. RCI (Process B) = 1 − ( ) = 0.25. RCI (Process C) = 1 − ( ) = 0.38

//////////green chemistry, drugs

Overcoming barriers to green chemistry in the pharmaceutical industry – the Green Aspiration Level™ concept

Scheme 1. Pfizer’s Commercial Synthesis of sildenafil citrate (Viagra™)

“Green chemistry” refers to the promotion of safe, sustainable, and waste-minimizing chemical processes. The proliferation of green chemistry metrics without any clear consensus on industry standards is a significant barrier to the adoption of green chemistry within the pharmaceutical industry. We propose the Green Aspiration Level™ (GAL) concept as a novel process performance metric that quantifies the environmental impact of producing a specific pharmaceutical agent while taking into account the complexity of the ideal synthetic process for producing the target molecule. Application of the GAL metric will make possible for the first time an assessment of relative greenness of a process, in terms of waste, versus industry standards for the production process of any pharmaceutical. Our recommendations also include a simple methodology for defining process starting points, which is an important aspect of standardizing measurement to ensure that Relative Process Greenness (RPG) comparisons are meaningful. We demonstrate our methodology using Pfizer’s Viagra™ process as an example, and outline aspiration level opportunities for industry and government to dismantle green chemistry barriers.

F. Roschangar,*^a   R. A. Sheldon^b and   C. H. Senanayake^a  

*Corresponding authors

^aChemical Development US, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, USA
E-mail: frank.roschangar@boehringer-ingelheim.com

^bDelft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands

Green Chem., 2015,17, 752-768

DOI: 10.1039/C4GC01563K, http://pubs.rsc.org/en/content/articlelanding/2015/gc/c4gc01563k#!divAbstract

“ALL FOR DRUGS” CATERS TO EDUCATION GLOBALLY, No commercial exploits are done or advertisements added by me. This article is a compilation for educational purposes only.

P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent

///////////green chemistry,  pharmaceutical industry

Production of High-Quality Diesel from Biomass Waste Products

The use of biodiesel has been promoted for the past decade as a substitute for fossil-based diesel fuel. However, it has become evident that its production competes with food production by engrossing cropland. To overcome this Corma has developed a process that uses 2-methylfuran which currently is isolated (280 × 10³ tonnes per year) from nonedible biomass ( Angew. Chem., Int. Ed. 2011, 50, 2375−2378). The first step is the trimerization of 2-methylfuran which takes place in water mediated by sulfuric acid in 94% yield. The trimer is then subjected to hydrodeoxygenation using a mixture of Pt/C and Pt/TiO₂ and 5 MPa of hydrogen in 97% yield. Of particular note was the use of no organic solvent in the process. This route opens new routes for the production of high-quality diesel from waste biomass.

High-quality liquid fuels are obtained from non-edible carbohydrates by energy-efficient processes. 2-Methylfuran, produced by hydrogenation of furfural, is converted into 6-alkyl undecanes in a catalytic solvent-free process (see scheme with 6-butylundecane). A diesel fuel is produced with an excellent motor cetane number (71) and pour point (−90 °C) and with global process conversions and selectivities close to 90 %.

AuthorsProf. Dr. Avelino Corma, ET AL

• DOI: 10.1002/anie.201007508

5-hydroxymethylfurfural (0.500 g, 3.95 mmol) was dissolved in 2-methylfuran (2.00 g, 24.4 mmol) at room temperature, Amberlyst-15 (50 mg) was added as catalyst, and the reaction mixture was stirred for 24 h at room temperature. Then, the catalyst was filtered out and washed with ethyl acetate. The filtrate obtained was concentrated under vacuum and the residue was purified by silica gel column chromatography (95 : 5 hexane : ethyl acetate changing to 70 : 30) and 5-[bis(5-methyl-2-furanyl)methyl]-2- furanmethanol was obtained (0.921 g, 3.39 mmol, 86% yield).

I.R. (neat) max: 3407, 3128, 2948, 2917, 1560, 1442, 1207, 1016, 958, 788 cm–1.-

1 H NMR (300 MHz, CDCl3)  = 6.22 (d, 1H, J=3 Hz), 6.05 (d, 1H, J=3 Hz), 5.97 (d, 2H, J=3 Hz), 5.89 – 5.90 (m, 2H), 5.40 (s, 1H), 4.56 (s, 2H), 2.26 (s, 6H), 1.75 (s, 1H).-

13C NMR (75 MHz, CDCl3)  = 153.3, 152.8, 151.6, 150.2, 108.7, 108.0, 106.2, 39.2, 13.6.-

HRMS m/z calculated for C16H16O4: 272.1049. Found: 295. 0970 [M+Na]+ .-

Elemental analysis: C16H16O4 required: C, 70.57; H, 5.92; found: C, 70.57; H, 6.09 %.

Synthesis of trissylvylmethane (2,2′,2”-methylidenetris[5-methylfuran])[20] from 2- methylfuran (Sylvan) and 5-methylfurfural employing a 5 : 1 molar ratio of 2- methylfuran and 5-methylfurfural in presence of para-toluenesulfonic acid as catalyst.

 In a 1-L three-neck round-bottom flask, equipped with a reflux condenser and a mechanical stirrer, 2-methylfuran (Sylvan, 600 g, 7.25 mol) and para-toluenesulfonic acid (13.8 g, 80.1 mmol) were placed. Under stirring 5-methylfurfural (160 g, 1.45 mol) was added at a rate of 120 mL/h at room temperature. The reaction mixture was stirred at 50 ºC until a total reaction time of 6 h. The aqueous phase was separated and discarded. The organic phase was treated with NaHCO3 and with MgSO4 and the excess 2-methylfuran was distilled off with a rotary evaporator. Distillation provided the desired product 2,2′,2”-methylidenetris[5-methylfuran] as a colorless liquid in 97% purity (120 ºC, 2 HPa; 365 g, 1.35 mol, 93% yield). A distillation residue of 49.1 g was obtained. 1 H NMR (300 MHz, CDCl3) δ = 5.99 (d, J=3.1, 3H), 5.93 – 5.89 (m, 3H), 5.39 (s, 1H), 2.27 (d, J=0.8, 9H).- 13C NMR (75 MHz, CDCl3) δ = 151.4, 150.7, 107.8, 106.2, 39.1, 13.6.

/////